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Instrumenting the Naval Postgraduate School Global Broadcast Service Testbed facility Watkins, John A Monterey, California. Naval Postgraduate School http://hdl.handle.net/10945/8539 Downloaded from NPS Archive: Calhoun

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WATKINS,

J.

NAVAL POSTGRADUATE SCHOOL Monterey, California

THESIS INSTRUMENTING THE NAVAL POSTGRADUATE SCHOOL GLOBAL BROADCAST SERVICE TESTBED FACILITY by John A. Watkins June 1997

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Master's Thesis

Instrumenting the Naval Postgraduate

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School Global Broadcast Service Testbed Facility author(S) John A. Watkins

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unlimited 13.

AB STRACT (maximum

The work

200 words)

reported in this thesis used readily available components to implement a data acquisition

system for a Global Broadcast Service Testbed data collection controlling software

is

from the transmitting

facility.

and

store

hardware with

necessary to collect signal power content of satellite signals at a given distance Precise measurement and calibration of a satellite receive signal

source.

accomplished by use of an Hewlett-Packard 8568B spectrum analyzer. collect

Use of

retrieved

data.

These

components

are

A personal

brought

computer

together

is

is

used to

LabVIEW

using

instrumentation software. This system provides an efficient means to collect signal data which can be

used to verify

satellite link

performance estimates. Calculations are performed using Matlab

analysis software. This thesis contains calculated and

and background noise levels

for the three satellite receive

School Global Broadcast Service Testbed 14.

subject terms.

measured values of

Satellite,

total

statistical

average carrier power

systems that comprise the Naval Postgraduate

facility.

GBS, DVB, DSS, Link Budget,

Carrier Power,

NUMBER OF

15.

PAGES 125

Background Noise Power, LabVIEW software, Matlab software, Instrumentation report

17.

SECURITY CLASSIFICATION OF REPORT Unclassified

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SECURITY CLASSIFICATION OF THIS PAGE Unclassified

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CODE

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OF ABSTRACT UL

Unclassified

Standard Form 298 (Rev. 2-89) Prescribed by

ANSI

Std 239-18 298-102

Approved

for public release; distribution

is

unlimited.

INSTRUMENTING THE NAVAL POSTGRADUATE SCHOOL GLOBAL BROADCAST SERVICE TESTBED FACILITY

John A. Watkins Lieutenant, United States

Navy

B.A., University of San Diego, 1990

Submitted

in partial fulfillment

of the

requirements for the degree of

MASTER OF SCIENCE IN INFORMATION TECHNOLOGY MANAGEMENT from the

NAVAL POSTGRADUATE SCHOOL June 1997

DUDLEY KNOX LIBRARY NAVAL POSTGRADUATE SCHOOL MONTEREY, CA 93943-5101

OX LIBRARY '

IA>

'GRADU

400>

ABSTRACT

The work reported

in this thesis

used readily available components to implement a

data acquisition system for a Global Broadcast Service Testbed data collection facility.

Use of hardware with satellite signals at a

and calibration of a

8568B spectrum data.

controlling software

is

necessary to collect signal power content of

given distance from the transmitting satellite receive signal is

analyzer.

A

source.

measurement

Precise

accomplished by use of an Hewlett-Packard

personal computer

is

These components are brought together using

used

to collect

LabVIEW

and store retrieved

instrumentation software.

This system provides an efficient means to collect signal data which can be used to verify satellite link

performance estimates. Calculations are performed using Matlab

analysis software. This thesis contains calculated and carrier

power and background noise

measured values of

statistical

total

average

levels for the three satellite receive systems that

comprise the Naval Postgraduate School Global Broadcast Service Testbed

facility.

VI

1

.

TABLE OF CONTENTS

I.

II.

INTRODUCTION

1

A.

BACKGROUND

B.

THESIS OBJECTIVES

1

3

PERFORMANCE ISSUES A.

SATELLITE COMMUNICATIONS THEORY 1.

5

Link Budgets

6

a.

Distance from Satellite Orbit

8

b.

Radio Frequencies

9

c.

Antennas

9

d.

Power Amplifiers

10

e.

Transmission Losses

10

f.

B.

5

Noise Temperature

1

FACTORS AFFECTING PERFORMANCE OF NPS GBS TESTBED 1

Signal power and Effective Isotropic Radiated

a.

b.

2.

Signal

Power

1

1

Effective Isotropic Radiated

Noise a.

Power

1

Power

13

14

Antenna Noise

15

b.

Transmission Line Loss

15

c.

Amplifier Noise

17

d.

Total System Noise

18

vii

..

3.

Eb/No

19

PERFORMANCE OF GBS

C.

1.

SBS-6, DSS,

AND DVB

19

Estimated Link Budgets for SBS-6. Echostar, and

DSS 20

Satellites

2.

Satellite Footprints for

SBS-6. Echostar, and

DSS

24

a.

Satellite footprint of

SBS-6

25

b.

Satellite footprint of

DVB

26

c.

Satellite footprint of

DSS

27

m. NPS INSTRUMENTATION TESTBED CONFIGURATION

HARDWARE

A.

1

2.

29

Integrated Receiver

Decoder (IRD)

Receive Antennas for GBS,

/

Low

Noise Block (LNB)

DVB, and DSS

6000 Bit Error Analyzer

3.

Firebird

4.

BTSA

5.

HP 8566B

6.

Personal Computer

36

Spectrum Analyzer

37

Spectrum Analyzer

37

40 40

1

National Instrument's Lab VIEW Software Version

2.

Matlab

Statistical

4.0.

Analysis Software Version 4.2

METHODOLOGY

A.

33

34

SOFTWARE

B.

IV.

29

40 41

43

LAB VIEW® SOFTWARE

43

1.

Virtual Instrumentation

44

2.

Virtual Instrumentation Design for Data Acquisition

44

vin

a.

3.

4.

5.

6.

B.

C.

Requirements

44

Basics of Virtual Instrumentation using Lab VIEW.

45

a.

Front Panel and Block Diagram

45

b.

Lab VIEW Menus

46

c.

Creating Objects

47

d.

Quick Access

e.

Lab VIEW Tools

47

f.

Saving Vis

48

g.

Opening and Closing Vis

48

h.

Running Vis

49

to Controls

and Functions

GBSTESTBED.VI

47

50

GBSTESTBED.VI

a.

Front Panel of

b.

Block Diagram of

GBSTESTBED.VI

GBSSUB.VI

50 53

62

GBSSUB.VI

a.

Front Panel of

b.

Block Diagram of

GBSSUB.VI

VI Hierarchy

63

68 71

RECORDING DATA

73

1.

Data Formats

73

2.

Sampling Size

77

3.

Sampling Frequency

78

MATLAB

78

IX

V.

VI.

1.

Datafilter Function

2.

Stage

3.

RG-1

4.

79

1

Function

80

1

Function

81

Intpwr Function

82

DATA RESULTS

85

A.

DSS SATELLITE SIGNAL

85

B.

DVB SATELLITE SIGNAL

88

C.

HUGHES

91

D.

ANALYSIS

SBS-6 SATELLITE SIGNAL

93

SUMMARY

97

APPENDIX A. CALCULATION OF RECEIVE ANTENNA ELEVATION ANGLES

99

APPENDIX B. CALCULATION OF TOTAL SYSTEM NOISE LEVELS

101

LIST OF REFERENCES

105

INITIAL DISTRUBUTION

LIST.....

107

.

LIST OF FIGURES

1

Displaying a typical Satellite to Ground Receive Station Link

6

common

7

2.

Typical Link Budget for a

3.

Power Received from an Isotropic Transmitter EIRP Coverage of SBS-6 Satellite

4.

Satellite

System

12

25

6.

EIRP Coverage EIRP Coverage

7.

KG Room rack mounted equipment for GBS CONUS Testbed

30

8.

GBS CONUS

32

9.

Typical Set-up with Receive Antenna

5.

of EchoStar Satellite of

DSS

26 27

Satellite

Testbed Receive Suite

LNB

and

IRD

34

10.

Receive Antennas on top of Root Hall

35

11.

Fireberd 6000 Bit Error Rate Test Equipment

37

12.

HP8568B Spectrum Analyzer

39

13.

Front Panel of the

51

16.

GBSTESTBED. VI Block Diagram for the GBSTESTBED.VI GPIB Address Box and HP8591A Read Axis VI Transgression Path for the GBSTESTBED.VI

17.

Format and Append Case Structure

59

18.

Input Specifications to Concatenate Function

61

19.

Text File Function VI Up-close

62

14. 15.

20. Front Panel of

GBSSUB.VI

Frequency Case Structure of GBSSUB. VI Block Diagram 22. Input box for Modifying Sample Size Criteria

VI Hierarchy

24. Output 25.

DSS

Data

56 57

64

21.

23.

54

69 71

72

File with

Header Information

....77

85

Satellite Signal

Power for DSS Channel 1 and 16 of the DSS Satellite Signal Background Noise Levels for the DSS Satellite Signal

26. Carrier

86

27.

87

28. Echostar

DVB

88

Satellite Signal

Power for DVB Channel 1 and 10 of the DVB Satellite Signal Background Noise Levels for the DVB Satellite Signal Hughes SBS-6 Satellite Signal Carrier Power for Hughes SBS-6 Satellite Signal Background Noise Levels for the Hughes SBS-6 Satellite Signal

29. Carrier

89

30.

90

31. 32.

33.

XI

91

92

93

Xll

LIST

OF TABLES

1.

Total System Noise Temperatures

18

2.

Estimated Clear Sky Link Budgets

20

GBS SBS-6, DVB, and DSS DSS System for the SBS-6 GBS CONUS System

3.

Atmospheric Losses of the

4.

Rain Loss for the

22

5.

Rain Loss

23

7.

DVB System Format Specifications for Lab VIEW Output Data

8.

Codes

9.

Theoretical versus Measured: Carrier and Noise

6.

Transmissions

Rain Loss for the Echostar

for Inserting Non-displayable Characters into

xin

Output Data

Power

21

24 75 76 94

XIV

ACKNOWLEDGMENT

There are several people willingness to assist Electrical

me

in

my

whom

like to

thank for their extraordinary

I first

want

to

acknowledge the

and Computer Engineering Department, particularly Jeff Knight,

software application.

He

and guidance throughout

would

would

research for this thesis.

unwavering support and assistance

Hankins

I

in learning

research efforts. Additionally,

I

assistance in

express

my

sincere thanks to Professor Colin

programming with Matlab

software.

Moose, of the Naval Postgraduate School, researching and writing this thesis. Finally,

Michelle whose

support and patience

xv

am

I

reserve this

with information

like to

GBS

Cooper

Hank

thank

Testbed.

I

also

for his technical

especially grateful to Dr. Paul

for his expert guidance

through

appreciated.

I

me

would

for his diligence in ensuring full systems operation of the

like to

his

and programming with the Lab VIEW

has been extremely generous in providing

my

for

my

and input while

biggest thanks to

my

experience are so very

wife

much

I.

INTRODUCTION

BACKGROUND

A.

Operation Desert Storm and exercises since then have shown that joint operations increased

require

communications high

satellite constellation is

continuous

volume,

communications

satellite

information

capacity.

oversubscribed and multiple

to

new

the

military

not designed to deliver

is

With

users.

constellations requiring replenishment in the years 2003-2007,

acquire

Currently,

existing

military

DOD plans are ongoing to

technologies to augment and/or replace current systems for future satellite

communications architectures one such system

Broadcasting

1990's,

The Direct Broadcast

1].

now being tested and

mid

In the

[Ref.

Satellite

(DBS) system

fielded for use in military applications.

Hughes Communications and the United

Company (USSB)

is

launched a

new

America. This service, known as Direct

States Satellite

generation of television service to North

Satellite

many

Service (DSS), distributes

channels of high quality digital video, as well as digital audio and data via Direct

Broadcast Satellites (DBS) to small (18' diameter) dishes and decoders that are purchased

by the consumer. In February 1995, the Deputy Assistant Secretary of Defense hosted a

DOD

DBS capability within the commercial DBS systems, the DOD

concept was officially renamed the Global Broadcast Service (GBS) [Ref.

An

emerging technology, Direct Broadcast

several technological barriers to quality as well as

CD

sound

become commercially

Satellites

satellite

viable to provide laser disk picture

to subscribers. Specific enabling technologies are the

military are tremendous.

A

military

The

GBS

potential benefits of is

DBS

ideally suited to the

extensive bandwidth using existing technology that rates

(MPEG)

video

algorithms,

transponders, inexpensive low noise microwave receivers, and

affordable high speed digital processors.

The high data

2].

(DBS) have overcome

compression techniques using the Moving Pictures Expert Group high power

C4I

conference to discuss concepts and plans for

an effort to avoid confusion with the

military. In

for

is

technology for the

DOD's need

for

both affordable and highly capable.

and large bandwidth associated with these types of

satellites

can be

exploited to provide simplex transmission of imagery, television, and data to a variety of users.

However, there

are major differences

between commercial use and military use of

DBS. For example, commercial programming

is

done months

in

advance and broadcasts

are limited to

broadcasts

TV

and audio. Additionally, the encryption incorporated

discourage nonsubscribers from accessing this service.

is to

commercial

in

The

military will

require full encryption to ensure security of classified information. Likewise, the 18'

dishes that receive these signals are suitable for receptions at home, but the military will require reception in less ideal circumstances. In particular, the mobile user will

need a

system that will allow reception on the move. There are proposals for interim and solutions to provide a

GBS

The implementation of these solutions

for the military.

final

will

require answering several questions such as the frequencies to be used, the type of satellite to

be employed

(light satellite or modification

of the broadcast management

organization

center,

of current

program), the

satellite

and more

encryption methods,

importantly here, the reception quality of transmission.

Commercial industry has developed

volume of

the capability to broadcast a high

data with the use of very small aperture antennas coupled with affordable receiving

equipment. This technology

is

easily adaptable to military

communications needs. The

technology embodied in commercial direct broadcast service (DBS) can be modified with additional

The

DOD

effort to

investment to serve the needs of the mobile user on the

modify and incorporate

Broadcast Service (GBS)

initiative.

DBS

technology

The use of DBS

is

move

[Ref.

1].

the backbone to the Global

to disseminate information provides

a tremendous gain over the current data rates available to disadvantaged users on the

move. Using high powered

satellites to

broadcast digital information to small aperture

antennas and inexpensive terminals, data rates ranging from 23 to 30 Million Bits Per

Second (Mbps) are possible

However, there are limitations to

[Ref. 3].

particularly in providing these data rates to a user

The sites,

GBS

broadcast

approach,

on the move.

system will be comprised of information sources, up-link transmission

satellites,

and receiver terminals as well as management processes for

requesting and coordinating the distribution of information products. will be serviced

this

by a primary up-link

site

Each

GBS

satellite

where information products are assembled and

transmitted to a high-powered satellite for relay to users over a large geographical area.

The development and deployment of GBS

Phase

I

(FY96-98)

—Limited

is

to

be accomplished in three phases.

Demonstration:

leased

commercial

transponders operating at Ku-band, used primarily for concept of operation

satellite

(CONOPS)

development, demonstration, and limited operational support. Transponders are being

leased on two satellites: Orion

CONUS GBS CONOPS Phase

II

(FY98-00) Interim Military

UFO

information

management

Follow

and

IFOR

for service to

in

Bosnia and Hughes SBS-6 for

development.

packages on

Infrastructure

I

On

Satellites

systems.

complete

Nr

Satellite Capability: Initial fielding

and

8, 9,

of

Integration

connectivity

with

of

GBS

Acquiring user terminals and

10.

GBS

various

with

Defense

providers

Information

of high-volume

information.

Phase

III

(FY00-02) Objective system: Fielded systems will be upgraded with

objective requirements with satellite constellation that will provide worldwide coverage.

Complete integration with

GCCS and other intelligence

broadcast and theater information

management systems.

This thesis focuses on issues being evaluated and researched in conjunction with

Phase

of the

I

GBS

process implementation.

demonstration of leased commercial primarily for concept of operation

satellite

communications systems;

specifically, the

analyzes and evaluates the limited

transponders operating at Ku-band, used

(CONOPS)

The author evaluates

operational support.

It

development, demonstration, and limited

the performance of three different satellite

GBS

SBS-6, Echostar Dish Network, and the

DBS DSS satellites. Experimental research on critical technical and functional aspects of the NPS GBS Testbed to include instrumentation analysis and monitoring results of the received carrier power and background noise levels on each transponder associated with the

GBS

broadcast

the

DSS

satellite signals are

Integrated

Receiver

provided. Continuous estimates of

Decoder (IRD) are provided

comparisons of measured data inherent to the

B.

Echostar Digital Video Broadcast

satellite, the

GBS,

in the

Echostar, and

C/N

each

satellite,

and

at the input to the

system.

Additionally,

form of calculated versus estimated link budgets

DSS

systems are provided.

THESIS OBJECTIVES The primary objectives of this

was

for

(DVB)

to construct

and synthesize a

readily available components,

thesis are

two

fold.

The

satellite signal collection

first

and analysis

which could collect and record

spectrum measurements. The second, to provide a limited

objective of this thesis

satellite

facility,

using

signal

power

statistical analysis report

of the

GBS, DVB, and DSS

reception quality at the

amassed by the collection

facility

NPS GBS

Testbed based on the data

.

Using the recorded signal power spectrum content from the collection

facility,

computation can be reconstructed and compared with estimated link budgets

link budget

the performance of various satellite communications systems.

for determining

collection facility

is

needed in order to confirm that previously calculated link parameters

are valid

and reasonable and

accurate.

The

that predicted link

performance of a particular system

numerous

collection facility described here enables

communications system signal power spectrum data combinations

of

The

transmitters

to

sets

of specific

is

satellite

be collected using various

and receivers. The data collection

facility

can be

reconfigured or modified to accommodate user-defined requirements.

Chapter

of

II

this thesis consists

of an explanation of

theory, including a description of satellite link budget affect satellite link performance.

Chapter

III

communications

satellite

components and the

factors that

provides the reader with a description of the

hardware and software components that make up the

NPS

Testbed

facility.

Concept,

design, operation, and graphical source code of the data acquisition system developed for the Testbed using

limited

Lab VIEW software, report

instrumentation

communications systems

described in Chapter IV. Chapter

the

link

comprise the

performance

NPS

of

the

V

provides a

three

satellite

Testbed. These include the average

power and expected background noises

received signal display

that

on

is

for each system.

Graphical

of the signal power spectrum content and noise spectrums are provided.

Following the summary presented in Chapter VI, Appendices calculations

By

of specific performance

criteria

made throughout

A

and B,

this writing.

using this thesis, and the information in the appendices, future

able to assess

and

utilize baseline estimates

background noise levels

for

the

contain

GBS

users are

of received carrier power and expected

GBS, DSS, and

DVB

systems. Furthermore, the

calculated link budgets provided can be used for comparison to future data accumulation

and analysis.

It

is

strongly suggested that the information contained in this thesis be

utilized in further testing

and analysis congruent with the

GBS

implementation process.

II.

PERFORMANCE ISSUES

This chapter addresses factors that effect important to understand the basic theory behind the factors that effect received signal

power

transmission performance.

satellite

satellite

strength.

It is

transmissions before addressing

Chapter

II

will begin with a brief

description of a telecommunications satellite system and then discuss the following

performance measures inherent to a

satellite

communications system link budget

calculation:

Power and

Effective Isotropic Radiated

•

Signal

•

Ground Receive Terminal Noise

•

Noise

•

Energy per

Power (EIRP)

in instrumentation devices

bit

Having presented

these, this chapter will then address factors that affect signal

reception quality. Finally, estimated link budgets using Satellite Tool Kit

and

satellite

footprint(s)

(EIRP coverage)

for each

(STK) software

system will be presented and

discussed.

A.

SATELLITE COMMUNICATIONS THEORY Most communication

The equipment

satellites are active repeaters.

in the satellite

receives signals from an earth station, translates them to a different frequency,

amplifies

them

package in the

for retransmission to satellite includes a

one or more earth

stations.

number of transponders

The communications

is

very weak. Consequently, the

satellite

amplifying the received signal and then transmitting earth.

Likewise, the signal power

earth station

must receive

sufficiently clear to

this

at

weak

signal, 1

amplify

it,

at the satellite

must have a means of a

new

at the receive earth station is

be decoded. Figure

downlink configuration.

it

bands

in adjacent frequency

each of which performs these functions. The signal power received the earth station

and

from

greatly

higher power level to

very weak. The receiving

and obtain a signal that

below displays a typical

satellite

is

uplink and

Satellite (Bentpipe)

\

\

/

\

/

\

/

\

/

\

/

\

/

\

/

\

/

\ Uplink Path

.

Downlink Path

/ /

/

Ground Uplink Site

Figure

1.

1

.

Ground Receive Terminal

Displaying a Typical Satellite to Ground Receive Station Link

Link Budgets

The performance parameters of a communications in a link budget.

Many

the link budget.

A

satellite)

satellite are typically

factors affect the signal transmission.

link

budget includes parameters of

and the ground segment

(the earth station).

The uplink includes

The downlink includes

the earth station receiver. Figure 2

shows a

that calculations are

an input to

the earth station

the satellite transmitter and

typical link budget for the

made

is

both the space segment (the

transmitter and the satellite receiver.

DirecTV system. Notice

Each of these

presented

for both the uplink

Hughes DSS

and the downlink

transmission paths. The terms within Figure 2 will be defined and discussed throughout the remainder of this chapter .J\

"

DSS DirecTV

Typical

Link Environmental Conditions Clear Uplink [Transmit EIRP, dBW Uplink path loss,

dB

Bandwidth,

;

Rain dowr

Rain up

76

86

w?

208

T

Atmospheric Loss, d6~ Uplink raihlossTdB Satellite G/T,

Link

:2rJ879"

-208.9 -0.3

gi

dB/K

5u -73ST

dB-Rz'

Bbltzmann's Constant, dBW Uplink C/N, Thermal, dB

24T6

-73.8

T378"

228T6

228.6

l4;g-

Downlink Transmit EIRP,

dBW

51

51

2

Q30O12

aHeniatocnfcr ether perce1aj=s

ErtertrBfreajaxyina-fcinos'l

E2

FarthspTDgantowakaairady, yxim^kncwthes Hicn la; axl long an the satellrte long

Ycum^a sogEdtyEaWaNaSinaeJlsF3+ti Refer to nUK hec 85/ map fcr ra n regcn an the ocbs referenoe wth Erterdarjees in ceils E3E6

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ranratetadefCTacprcpnateranirtenaty. Ertervauemcell E22

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Erter the paoatec^cf year thBtyoivgt in oell

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ThsisyaraBAer. This isthe anrart cr ran magn trat ^xr lirk mjBt have to dceeyxr lirk tat repaoertagecf

the ^ear tret yaiwat

^able

i 5.

Rain Loss for the SBS-6

23

1

3BSC ONUS

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r

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a^rb

NDIh4 P

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Lg

w w

366 N

aajcnLamrfe

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UBVNVI

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122

Hevabcnarge

oavFurro OaVFUTED OJVHJIbD OJVRJILD OOVFUTED OOVFUIED OOVFUTED OOVFUTED

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This Spead Sheet

DVB USER INPUT USER INPUT USER1NPUT USER INPUT

COMPUTED COMPUTED USER INPUT COMPUTED COMPUTED USER INPUT COMPUTED COMPUTED COMPUTED COMPUTED COMPUTED COMPUTED COMPUTED COMPUTED COMPUTED USER INPUT COMPUTED COMPUTED

NOTE1 NOTE 2

is

USA model.

the

Enter only the values labeled user input Refer to notes.

NOTE1 F NOTE 2 lo NOTE 2 NOTE 2 Ls

Freq

GHz

in

Satellite

12.2

w w

2.076942

r

2.126392

LONG CO

36.6

N

0.638791

119

Station Longitude

I

121.8333

Longitude

Station Lattitude

47.43796

Elevation angle

Freezing Height during rain

Hfr

NOTE 2 Hs

0.2

Ls

Slant Path Length

5.132067

Lg

Horizontal Projection

3.471269

Rain Rate mm/hr

19

Freq-dep coefficient a

0.017917

b

Freq-dep coefficient b

1.160357

aRr/b

specific attenuation (dB/km)

rh.01

Horizontal path adustment

1.677859

?

angle comparitor

0.790511

Lr

adjusted path length

5.132067

rvO.01

Vertide Reduction Factor

1.095316

Le

Effective path length

5.621238

A0.01

Attenuation exceeded for .01%

3.068426

a

NOTE 4 P

545863

Other percentage

1

-0.003

z

NOTE~5~ Ap

attenutation for other percentages

Enter the frequency

GHz

in

in cell

0.189592

E2.

For this program to work accurately, you must know the station Enter degrees

NOTE 3

0.827949

3.98

Station Height

NOTES R

42164.2

W

in cells

You must

E3-E6.

Refer to ITU-R Rec 837

map for rain

also specify

E

or

lat

and long and the

W or N or S

in cells

satellite long.

F3-F6.

region and the cross reference with

rain rate table for appropriate rain intensity. Enter value in cell E22.

NOTE 4 NOTE 5

Enter the percentage of year that you want

in cell

E22.

This

is

your answer.

This

is

the amount of rain margin that your link must have to

I

dose your

link for

the percentage of

the year that you want.

Table

The

figures

EIRP coverage

Looking

Rain Loss for the EchoStar

Satellite Footprints for

2.

the

6.

at

below (Figures

is

4, 5,

and

6),

provide the reader with an aerial view of

an EIRP map, one can determine the transmit

power

within the

DSS

area for the three satellite systems comprising the

46 dB W. This value

to-noise

System

SBS-6, Echostar, and

geographical area. For example, in Figure 4 the SBS-6 area

DVB

is

used

in link

EIRP

satellite

are subject to change based

on

EIRP maps

EIRP

Testbed.

for a given

for the Monterey, California

budget calculations for determining the carrier-

ratios for a particular geographical location

satellite's footprint.

NPS GBS

assuming the location

are generally provided

satellite orbital

24

adjustments and

is

by the manufacture and

satellite longevity.

a.

Satellite footprint

o/SBS-6

'•:.'

V,'

wmmmmm

V

.••'. .>.

^%/»'« A>'-'

Figure 4

EIRP Coverage of SBS-6

25

Satellite

^ii;:-.':-:'

b.

Satellite footprint

ofEchostar D VB

Figure 5

26

EIRP Coverage ofEchostar

Satellite

c.

Add

2.9

Satellite footprint

ofDSS

dBW for transponders with 240 W power.

Figure 6

EIRP Coverage of DSS

27

Satellite

28

III.

NPS INSTRUMENTATION TESTBED CONFIGURATION

HARDWARE

A.

This chapter will examine the hardware and software currently installed in the

NPS

Testbed.

It

hardware and software that will be

will also discuss

installed for

GBS

research in the future.

A

receive

GBS

site

Laboratory (SSTL)

Testbed

is

installed in the

NPS. The purpose of

at

the Testbed

research on critical technical and functional aspects of the

The Testbed

consists of two

Ku band DSS

Secure Systems Technology

(at the

A

one meter antenna

is

installed

time of this writing, the SBS-6

to conduct experimental

GBS, DVB, and DSS

commercial systems, one

commercial system, and one system receiving the Phase broadcast.

is

and

is

receiving

satellite is at

W, and an

1

19 degrees

GBS Ku band CONUS the GBS CONUS broadcast

89 degrees W).

the

SSTL

laboratory.

Two

DBS

additional .45 meter antenna receives the EchoStar

W. The

Ku-band

I

meter antennas receive the DirecTV broadcast from the Hughes degrees

DVB

systems.

standard .45

satellites at

DVB

101

broadcast at

antennas are installed on top of Root Hall, in close proximity above

Each of the

DSS

commercial systems have two Integrated Receiver

Decoders (IRD) and two television monitors.

The

GBS

system currently has two IRDs, one decoding video and the other to install a third

IRD

ATM protocols). The data IRD and associated C.D.I,

data

decoding IP data. (At the time of

which

will support

bridge

is

decoding of

connected to a

SPARC

this writing, plans are

underway

20 workstation through a

KG- 1 94

encryption device and

GBS configured workstation is on the SSTL secure net that supports the workstations of the NPS Global Command and Control (GCCS) installation. This net is connected to other GCCS sites and elsewhere through a 512Kbps SIPRNET secure connection. An appropriate antenna and LNB to receive the UFO K-band 20.7 GHz GBS broadcast will be installed in the future [Ref. 6]. Figure 7 below displays the rack mounted KG- 194 encryption device along with an IRD and data bridge assembly. These components make up the SBS-6 GBS CONUS receive system. The secure crypto a

CISCO 2514

room

is

router.

The

located on the second floor of Root Hall and

only.

29

is

accessed by authorized user's

Figure 7

KG Room rack mounted equipment for GBS COXUS Testbed

The

DVB

EchoStar system

channels and a data channel. The monitor.

The

The EchoStar system

is

comprised of one

IRD

is

located in the

utilizes the

IRD decoding

SSTL and

is

a

number of video

displayed on

its

own

DVB variable data rate transmission technique.

variable data rate allows for transmission to occur at ranges from

1

Mbps

to

50

Mbps

depending on what type of information products are being disseminated and the

bandwidth and power of the system

and

at

the

NPS

GBS SBS-6

Testbed

is

satellite

to study

transponder.

The purpose of

installing a

and compare the performance of DVB

to the

DVB DSS

satellite transmissions.

Test monitoring equipment

is

installed to record received carrier

power of each of

the active transponders and their background noise levels. This equipment consists of an

HP 8568B

digital

spectrum analyzer connected via a GPIB/HPIB interface to a

Pentium equipped with

LabVIEW

and Matlab software for recording, analyzing, and

displaying data from test instruments.

PCMCIA-GPIB

The

interface is

plug and play card designed for

PC

Fireberd 6000 bit error analyzer will be interfaced with the It

will also use the

and

PCMCIA-GPIB

PC

made through

applications.

PC

Pentium

connection to conduct research in

analysis.

31

the use

of a

Additionally, a in the near future. bit error detection

CONUS

Naval Postgraduate School Testbed GBS Receiver Suite Prodelin

(1I50 Norsat 0211

KIJ Band

LNB: (II 7-1 2.2

74degW

ill

1111

SBS6:

DBS

1.2,3:

degWEvhoslarl.2:

U9degW

Firebird

60(1(1

Communications Analyzer

Vertical Polarization

Orientation

Typical

CONUS GBS Channel Assignment CNN HN or Video Feed

IRD Channel 100 IRD Channel 101 IRD Channel 02 1

-

/

when broadcast

-

IP data

-

ATM data "

TV Monitor

Data

cdi

Bridge

13226420-02

KG

C tYPTO

KeymaL ISKAT 272(1 (Allied

94-A

ROUTER

Signal) 1

SUN

Cisco

2514w/AUIto

Sparc

lOBaseT

OBaseT Adapte

2071

GBS

Workstation

Sun Sparc 2071

Test

Locations

Spectrum ) /

, *

150

Analyzer

HP 8568B

Pentium 150

) /

,

*

MHz

Pentium

PC

Labview Signal Analysis Software

Figure 8

MHz

GBS CONUS

w/GPIB connection

Testbed Receive Suite

32

75

MHz, 1MB

Cache

RAM,

1

MB

28

2

@4

GBHD Solaris 2 5

1

Figure

8, represents the

receive antennas are located on the roof of Root Hall. the receive antenna(s)

rooms on the second because of

low

its

receive antenna)

is

RG-1 1

Testbed

RG-1 1

floor of Root Hall.

line loss.

coaxial cable

The coax cable from the

routed to the secure crypto

CISCO

TV

router,

A 75 Ohm splitter device

is

room which houses

KG- 194

forwarded to

is

Secure Systems Technology Lab (SSTL). The data signal

its

is

routed from

three systems

all

GBS SBS-6 IRD and

the first

a

encryption/decryption

installed in order to separate the

from the video content. The video signal

The four

the roof into various

used in

is

is

meter dish (the

1

monitor, and

suite.

coaxial cable

low noise block(s) (LNBs) down through

stand alone data bridge, device.

NPS

physical layout of the

incoming data signal

own IRD

sent to

its

located in the respective

IRD

followed by the data bridge (buffers incoming data while awaiting decryption). The data signal

terminal located in the (.45

SSTL down the

hall

meter (m) receive antennas for the

coaxial cable to their

a

KG-194 and subsequently

then decrypted via the

is

TV

IRDs which

routed to the

SPARC

20

from the crypto room. The remaining systems

DVB

and

DSS

signals) are connected via

are also located in the

SSTL. Each system

RG-1

is fitted

with

monitor for viewing video content.

The SSTL

is

equipped with a 150

MHz PC

which runs the

LabVIEW

software application fundamental to the instrumentation process described in this thesis. Additionally, an Hewlett-Packard

BTSA

HP8568B spectrum

analyzer and a Blonder-Tonge

spectrum analyzer also are maintained in the SSTL.

portable

These two

instruments are essential for the data acquisition of the signal received in each of the three satellite

GPIB

systems.

The HP8568B spectrum analyzer

interface for instrument control

The remainder of comprising the intent

NPS GBS

this

PC

via a

PMCIA-

chapter

addresses

individual

Testbed. Each hardware device

is

hardware

components

described briefly with the

of familiarizing the reader with the basics of each component. These components

error analyzer,

LNB LNB is

The

and GBS, the Fireberd 6000

HP 8568B

bit

spectrum analyzer,

computer.

Integrated Receiver Decoder (IRD)

.

The

DVB, DSS,

Blonder-Tonge spectrum analyzer (BTSA),

PC Pentium 1

unit.

coupled with the

and data acquisition.

consist of the IRDs, receive antennas for

and a

is

/

Low

Noise Block (LNB)

consists of a low noise amplifier and downconverter contained in one

designed to receive the incoming signal which

33

is first

amplified by the

low noise block amplifier mounted on the receive antenna.

It

amplifies the signal to an

GHz

to

950-1450

acceptable level and

The L-banc

signal

is

down

converts

sent via the

it

RG-

from 11.7-12.2 1 1

IRD

transmission line to the

MHz

(L-band).

demodulation

for

followed by decoding via the decoder. Figure 9 shows a typical set-up with an

LXB

and

IRD.

A

LNB

Receive Antenna

IRD

Monitor

Demodulator

Figure 9 Typical Set-up with Receive Antenna,

Receive Antennas for GBS,

2.

The

own

LNB

and IRD

DVB, and DSS

three satellite receive systems addressed in this thesis are fitted with their

receive antennas.

The antennas themselves

on top of Root Hall on the

XPS

are located

campus. The SBS-6

GBS

on a mounted plywood deck

system uses a

1

m commercial

type reflecting dish with base plate and pole for mounting on a level surface. The (feed horn),

a .83

dB

which receives

the reflected signal off the

noise figure and 62

1

m dish is a XorSat KU LXB with

dB of gain.

Like the SBS-6 receive antenna, both the

DSS

and

with similar receive antennas with the exception of aperture receive antennas are .45

m

LXB

in

DVB size.

systems are equipped

Both the

DSS

and

DVB

diameter and likewise are connected to their respective

34

IRDs using RG-1 1.4

dB and

1.28

1

coaxial cable. Xoise figures for the

cB

respectively. Gains are 56

dB - 6 dB.

four satellite receive antennas on top of Root Hail that

The

1

m GBS COXUS

receive antenna

is

is

located in the back

left

and

DVB LXBs are rated at

Figure 10

make up

the

is

left.

Figure 10 Receive Antennas on top of Root Hall

Testbed.

two DSS

The EchoStar

of the picture.

35

a picture of the

XPS GBS

pictured to the right, while the

receive antennas are aligned in parallel towards the

antenna

DSS

DVB

RCA

receive

1

Fireberd 6000 Bit Error Analyzer

3.

In support of bit error identification and study, a Fireberd is

to

NPS

be installed permanently in the

6000

bit error

analyzer

instrumentation Testbed. The Fireberd 6000

is

a multifunction communications analyzer that can terminate a variety of communications

and analyze the quality of the

circuits

circuit

under

Locations in which the Fireberd

test.

can be used include earth receive stations such as the location

where access

in the Fireberd test [Ref. 7].

and timing.

Testbed receive

site.

The

to the circuit can be gained determines the interface that is installed

6000. The interface provides the physical connection to the circuit under

The

An

NPS

interface also provides proper termination, signal conditioning, framing,

optional interface

is

inserted in the Fireberd interface slot

and then either

controlled locally or remotely. This allows the user to operate the Fireberd locally by

using the front panel switches and controls, or remotely by using a suitable remote controller. In the

NPS

instrumentation Testbed, the Fireberd upon installation, will be

controlled remotely by a

The

Fireberd

PC uses

using National Instrument's Lab VIEW software. digital

interfaces

to

test

Tl,

CCITT,

synchronous/asynchronous circuits and equipment. In addition to

its

DDS,

and the

versatility,

Fireberd provides for combining bit error rate testing with performance, signal, and

timing analysis. Future work will address

atmospheric affects, and protocol effects on

DSS, and

DVB receive signals.

(BER) observations on site

was required

bit

error

DVB

content,

bit errors across all three

Presently, the Fireberd

the Echostar

rate

is

burst frequency,

systems; the SBS-6,

being utilized for Bit Error Rate

system. Coordination with the Echostar uplink

since a bit test sequence has to be inserted into the transmitted signal.

This predetermined sequence provides the necessary baseline for determining if bit errors

have occurred Fireberd

6000

at the

as

it

end of the receiver. The author includes will

spectrum analyzer using instruments such as the is

front panel

be remotely operated

LabVIEW

in the

this brief description

same manner

as the

of the

HP8568B

software. This remote controlling and reading of

HP8568B spectrum

analyzer

is

view of the Fireberd 6000 Bit Analyzer.

36

covered in Chapter IV. Figure

1

Figure

1 1

Fireberd 6000 Bit Error Rate Test Equipment

BTSA Spectrum Analyzer

4.

The BTSA-3 Blonder-Tongue multifunction support installation of

systems and ground installation

of the

satellite

stations.

NPS

TV

satellite

analyzer

is

designed to

distribution networks as well as professional

The BTSA-3

satellite

Testbed. This device

is

VSAT

analyzer has proved crucial to the

used for locating the proper

satellite

and

adjusting the pointing and polarization of the receive antennas for the strongest signal possible.

The BTSA-3, being

and easy to use.

radio, is both lightweight

5.

HP 8568B

The HP8568B

is

Spectrum Analyzer

a high performance, 100

instrumentation and test use.

measurements down

battery operated and approximately the size of a small

to 10

The frequency

Hz of

to 1.5

GHz

of the

stability

spectrum analyzer for

HP8568B

allows for

bandwidth. At this narrow bandwidth, the spectrum

analyzer yields noise levels as low as -135 its

Hz

dBm

[Ref. 8].

The HP8568B was chosen

for

exceptional ability to allow for very accurate measurements of small signals in the

presence of large ones. Multiple traces can be displayed to measure and conduct real-time surveillance over a wide frequency range.

As mentioned

37

earlier, the

HP8568B

allows for

this real-time surveillance

over the L-band intermediate frequency range of 950 to 1450

MHz which is ideal for all three satellite signals addressed in this writing. The most

element

critical

in the

instrumentation Testbed

is

the

HP 8568B

spectrum analyzer. This device offers superb accuracy over a wide range of precision

measurements. In addition,

this

measurements taken directly These

system can also used for determining line loss figure

after the

antenna

LNB

and

at the cable termination points.

line loss figures are necessary for accurate received-signal

power measurements

and subsequent link budget comparisons.

A potential user of this instrument should realize that at

its

signal input socket

—

as with the

it

BTSA-3 spectrum

does not allow analyzer.

To

DC voltage satisfy this

Ohm combination insertion block/blocking capacitor (DX Antenna, Model adjustable DC power supply (Hewlett-Packard, Model 62 15 A) are used to

dilemma, a 75

CP-7) and

power

the

requisite

the

DC

LNB's during measurement

LNB DC power directly

into the

current from flowing into the

periods.

RG-1 1

These devices enable insertion of

coaxial cable, and simultaneously block

HP 8568B

analyzer. This device is rated at an

average insertion loss of approximately 0.5 dB. Figure 12

8568B spectrum

analyzer.

38

is

the front panel of the

HP

Figure 12

Currently, the

NPS

analyzer connected to a

PC

HP 8568B

Spectrum Analyzer

instrumentation Testbed for

is

using an

HP8568B spectrum

remote control and data acquisition. To decrease the time

required for conducting signal power measurements and to improve data acquisition, a

PC-based "Virtual Instrumentation" or VI package developed by National Instruments being used (National Instruments

LabVIEW

Software). This software enables a

PC

is

to

remotely control the spectrum analyzer as well as collect, mathematically manipulate, and store

HPIB

measurement or

GPIB

data.

The

interface

between the spectrum analyzer and the

standard interface. The

port to receive the National Instrument's

PC

is

equipped with a

HPIB/GPIB

39

PC

PCMCIA-GPIB

interface card.

is

the

adapter

Personal Computer

6.

A

MHz IBM

166

type personal computer

HP8568B spectrum

collection of/from the

byte hard-drive with 16 Megabytes of

(upwards of 20 Mega-byte

computer

with

loaded

is

files),

analyzer.

and data

The computer maintains a

1.6 Giga-

RAM. To

an external

National

utilized for controlling

is

1

support extensive data collection

00 Mega-byte Zip drive

Instrument's

LabVIEW

is

pre-recorded using the

satellite receive signals

test run, the

data

is

LabVIEW

and

software

Laboratory (Matlab) Statistical Analysis software. The Matlab software

mathematical data manipulation, graphical interpretation, and

being used. The

is

Matrix

being used for

statistical analysis

software.

of the

Upon completion of a

saved onto the Zip drive and then loaded into Matlab for manipulation

and analysis. Specific manipulation and

statistical analysis

programs (.m

files in

Matlab),

are described in Chapter IV.

B.

SOFTWARE As revealed

LabVIEW

Matlab

and

two separate software packages, National Instrument's

earlier,

Analysis

Statistical

Tool,

are

being

used

in

the

NPS

instrumentation Testbed. This section briefly explains the advantages of using both

LabVIEW and

Matlab for measurement, analysis, and National Instrument's

1.

LabVIEW

software

LabVIEW

interpretation.

Software Version 4.0

a program development application,

is

BASIC. However, LabVIEW

is

different

much

from those applications

programming systems use text-based languages

to create lines

in

of code, while

like

C

that

other

or

LabVIEW

uses a graphical programming language, called G, to create programs in block diagram form.

LabVIEW,

like

C

or

BASIC,

is

a general-purpose

extensive libraries of functions for any programming task. for data acquisition,

and data storage In the

GPIB and

serial

programming system with

LabVIEW

includes libraries

instrument control, data analysis, data presentation,

[Ref. 9].

NPS

instrumentation Testbed,

LabVIEW

is

used for data acquisition,

GPIB

instrument control, data analysis, and data storage. Data manipulation and graphical presentation later.

is

accomplished through the use of Matlab software which will be addressed

Use of LabVIEW eases

analysis,

and storage.

It

significantly the time required for data accumulation,

has facilitated a "hands off approach to data collection which

40

has resulted in parallel productivity in other areas of the instrumentation Testbed

measurement

Instrumentation" which

Matlab

2.

Matlab

Lab VIEW

process.

is

is

uses

covered in detail

Statistical Analysis

in

a

technique

referred

to

"Virtual

as

Chapter IV.

Software Version 4.2

both an environment and a programming language that allows the user

to build reusable "tools" [Ref. 10].

programs (known as

M

or .m

algorithms in a few dozen

Using Matlab, one can create special functions and

files) in

lines, to

Matlab code. Matlab allows the user

to express

compute the solution with great accuracy

in a

few

seconds on a PC, and to readily manipulate color three-dimensional displays of the results.

The

results

provided

in this writing are arrived at

by the author. Using Matlab provides the capability sets with relative ease

and superb accuracy

to

in results.

41

using Matlab code

—generated

manipulate and process large data

42

METHODOLOGY

IV.

This

chapter

and then discusses the methodology employed in

introduces

conducting the instrumentation of the National Instruments

LabVIEW

NPS GBS

Testbed.

and Math Work's

covers both the use of

It

Matlab software. This chapter

Inc.

explains the use of these software packages from the perspective of system requirements,

design

analysis,

design

issues,

and

specifications,

obtained.

results

A

thorough

explanation of the virtual instrument(s) or Vis that were used in the instrumentation of the

NPS GBS

Testbed

this application are

is

provided. In addition, descriptions of Matlab .m files written for

provided for user

clarification.

LABVIEW® SOFTWARE

A.

Recall that National Instrument's

LabVIEW

software

is

an application that allows

for remote controlling of an instrumentation device while simultaneously accumulating

data from

it.

which were used principle behind

the

G

comes equipped with extensive

In addition, the software

for data interpretation in conjunction with

LabVIEW

is

program code

environment [Ref.

9].

that

Matlab software. The basic

the concept of virtual instrumentation. In

programming language, the user develops

actual

LabVIEW,

virtual instruments (or Vis)

using

which are

can be manipulated in a graphical user interface (GUI)

The software

is

heavily populated with pre-existing Vis which can

be modified to suit one's particular instrumentation needs. environment, the need for an interface VI with the error analyzer

analysis functions

were identified early

in the project.

HP 8568B

In

the

NPS

Testbed

and the Fireberd 6000

bit

Through use of existing Vis, a rapid

prototype was put together very early in the stages of installation of the Testbed. At the

time of

this writing there exists a fully

spectrum analyzer.

A VI

is

developed VI for interface with the

HP 8568B

being developed for interfacing with the Fireberd 6000 which

will serve to control that instrument

and collect data on

bit error

content in a real-time

mode.

The VI designed need as

arise for future

much

for the

HP 8568B

VI development,

took considerable time and

the author strongly

as possible. In the case of the

HP 8568B

effort.

recommends using

analyzer this

Should the

existing Vis

was not an

option.

Consequently, the VI was developed from scratch, module by module, until completion.

43

— Virtual Instrumentation

1.

The

traditional instrument is self-contained, with signal input/output capabilities

and fixed user interface features such as knobs, switches, and other instrument

specialized

circuitry,

including

A/D

converters,

features. Inside the

signal

conditioning,

microprocessors, memory, and an internal bus accept real-time signals, analyze them, and present results to the user. Typically, the vendor defines the user cannot change

it.

the instrument functionality

open architecture of

Virtual instruments leverage off the

industry-standard computers to provide the processing, off-the-shelf, inexpensive

all

DAQ

boards and

GPIB

memory, and

interface boards

display capabilities;

plugged into an open,

standardized bus provide the instrumentation "front end" capabilities. Because of the

open architecture of PCs and workstations, the functionality of virtual instruments

and thus scaleable and

defined,

The fundamental concepts of

extensible.

is

user

virtual

instruments directly translate to bottom-line benefits for the user. The user, not the

vendor, defines the ultimate functionality of the instrument. Virtual instruments leverage off the computer engine to deliver fast return on technology with

life

cycles of one to

two

years [Ref. 9]. 2.

Virtual Instrument Design for Data Accumulation

Requirements

a.

The

designing a VI for the accumulation of data from the

first step in

H8568B spectrum

was

analyzer

and

determining

subsequently

defining

the

VI

requirements. The requirements are the following:

•

The VI must acknowledge

the

HP 8568B

spectrum analyzer through the

GPIB

interface.

•

The VI need

not be able to control the

HP 8568B

the front panel on the spectrum analyzer collection purposes.

The only

was

entirely.

User adjustment of

sufficient for envisioned data

control feature of the

VI required

is its ability

trigger the instrument device for requested data.

•

The VI

will display the frequency and amplitude

receive signal in two ways: 1)

—one

samples; two rows

A2x

of the incoming

satellite

1001 matrix (Array containing 1001

frequency, the other, amplitude) with resulting

44

to

frequency in

Hz and

amplitude values as pre-set in significance of digits by

A graphical depiction of the incoming satellite receive signal with

the user. 2)

the X-axis displaying frequency and Y-axis, the amplitude in dB. •

The VI

be designed such that the user can input the

will

file

storage path for

resultant data storage.

•

The VI

will be designed to run either once or at periodic intervals for user

selected data collection periods.

•

The VI

will be designed with time and data in

mind such

that at

each run of

the program, the time and date will be annotated in the data output file and

comments can be input

specific file

•

The VI of the

will be designed

HP 8568B

the user in a

GUI

to stored data file.

such that any change made to the front panel settings

analyzer will be reflected on the VI front panel as viewed by

environment.

HP

•

The VI

will

•

The VI

will be able to run with or without data output being saved to a file.

•

The VI

will

be very similar in appearance to the front panel of the

have the capacity to modify data storage formats such that

be able to export data usable by other software applications

These requirements were

(GBSTESTBED.VI), being used

in the

all

NPS

(e.g.

met and are functioning

it

will

Matlab).

in the current

VI

instrumentation Testbed.

Basics of Virtual Instrumentation using

3.

8568B.

LabVIEW

This section discusses basic features that the user needs to be familiar with in order to create or use Vis, including information about the front panel and block diagram

windows,

LabVIEW

learn such as

how to

palettes

and menus.

create objects,

change

It

also discusses basic tasks the user needs to

tools, get help,

and how

to open, run,

and save

Vis.

a.

Front Panel and Block Diagram

Each VI has two separate but

related

windows: the

block diagram. The user can switch between windows with the

Diagram command

in the

Windows menu. Using

45

the Tile

front panel

and the

Show Panel/Show

commands,

also in the

Windows menu,

the user can position the front panel and block diagram

windows

side-

by-side (next to each other), or up-and-down (one at the top of your screen, and one at the

bottom of your

screen). If the user

active VI. This selected. All

is

the

has multiple windows Vis open simultaneously, only one

VI whose

front panel or block

diagram

open front panels and block diagrams are

Windows menu, and

the

foremost or currently

is

at the

listed

is

bottom of the

the active front panel or block diagram has a check-mark beside

its

respective name.

The

front panel

is

representative of

the front panel

on the instrument

device being controlled or interfaced with the VI. Most Vis are designed such that the front panel looks as close as possible to the instrument being used.

When running

the user will usually execute a run from the front panel where s/he can see the

and producing desired appear

is

results.

When

opening Vis from saved storage, the

the front panel and unless the user intends to

user will exercise the front panel most often

On the new Vis, do

VI running

first

screen to

LabVIEW

code, the

when working with Vis.

other hand, the block diagram

takes place. If the user wants to

program in

the VI,

make changes

is

where programming

to existing

Vis or

if

in

LabVIEW

they wish to develop

s/he will utilize the block diagram portion of the existing or

newly

untitled

VI

to

so.

b.

LabVIEW Menus

LabVIEW window

menu

uses

menus

extensively.

contains several pull-down menus.

When

The menu bar

the user clicks

such as Open, Save, Copy, and Paste, and

LabVIEW. Some menus user will use most often

also is

list

many

shortcut key combinations.

the object pop-up

mouse

object's pop-up

menu. Virtually every

menu, put the cursor on

button.

46

common

to other

others particular to

The LabVIEW menu

well as empty front panel and block diagram space, has a pop-up

commands. To access an

top of a VI

on a menu bar item, a

appears below the bar. The pull-down menus contain items

applications,

right

at the

LabVIEW menu

the

object, as

of options and

that object

and click the

Creating Objects

c.

The user can selecting

them from

name of

known

As

moves

the user

the selection

on which can be

name on

name of the new

button, and place the object

arrow over an object on the

easily selected

object. If the user

When

the keyboard.

palette,

wants

to give the object a

It is

important to note that

created on a front panel, a corresponding terminal

diagram for the VI. This terminal

is

name,

is

by

when an

created on the block

used for reading data from a control or sending data

to an indicator. If the user wants to see the corresponding

created, select

from the Controls

finished entering the name, end text entry

pressing the key on the numeric keypad. is

from the

it

create front panel objects, they appear with a label rectangle ready for

the user to enter the

object

mouse

select

the object will appear at the top of the palette. Typical objects are knobs,

When you

enter the

and block diagram by

would

object on a front panel, s/he

toggles, switches, buttons, and so palette.

front panel

palette of the Controls palette, click the left

inside the front panel.

the

on the

the floating Controls and Functions palettes. For example, if the

user wants to create a

Numeric

create objects

Windows»Show Diagram. The

diagram for the front panel

block diagram contains terminals for

all

front panel controls and indicators.

Quick Access

d.

to Controls

and Functions

If the user needs several functions to

from the same

palette, he/she

may want

keep a palette open permanently. To keep a palette open, select the push-pin in the top

left

comer of the

palette.

can be moved around

Once

the user has pinned a

easily. If the

the palettes will be opened in the

VI

same

is

In

then saved, the next time

locations they

LabVIEW,

were

a tool is a special operating

user can use tools to perform specific functions.

Windows. The

open,

it

has a title-bar that

LabVIEW

is

opened,

last left.

LabVIEW Tools

e.

in the floating

window

Many

mode of the mouse

cursor.

of LabVIEW's tools are contained

Tools palette which can be accessed through the pull-down menu user can

clicking on the close box.

Windows»Show

move Once

The

the tool palette anywhere, or can close

it

titled

temporarily by

closed, the tool palette can be accessed again by selecting

Tools Palette. The user can change from one tool to another by doing

any of the following while

in edit

mode:

47

•

Click on the tool desired in the Tools palette.

•

Use

key

the

to

move through the most commonly used tools

in

sequence. Press the spacebar to toggle between the Operating tool and Positioning tool

•

when the front panel is active, and between tool when the block diagram is active.

the

Wiring tool and Positioning

Saving Vis

/

menu concern

Five options in the File the Save option to save a

new

VI, choose a

name

saving Vis as individual

and specify

for the VI,

the disk hierarchy. Also use this option to save changes to an existing

previously specified. If the user wants to save a VI with a

As ... Save a Copy As ,

When memory

.

.

.

,

or Save with Options

selecting the

to disk with the

name

Save As.

.

.

.

.

.

new name,

from the

file

new

version. In addition,

refer to the

new

VI. If the user enters a

the old

new name

saves a copy of the VI in

This does not affect the

s/he can use

name of

the

VI

in

Save

menu.

VI

memory

for the VI,

to disk

VI

that are in

overwrite or delete the disk version of the original VI. If the Save

LabVIEW

in a location

Lab VIEW saves a copy of the VI

option,

all callers to

Select

destination in

VI

specified. After the save is finished, the

points to the

selected,

its

files.

in

in

memory

memory now

LabVIEW

A Copy As...

does not option

is

with the name specified.

memory. Save with Options... brings up a

dialog box which the user can choose to save an entire VI hierarchy to disk, optionally

saving Vis without their block diagrams. This option distributing

Vis or

having saved including

its

it

is

making backup

NOTE: The

without a block diagram. Always

make

in

LabVIEW

is

done much

the user

user cannot edit a

VI

is

after

a copy of the original VI

in the

same manner

as opening a

a typical word processing software application. The user can open an existing VI

by using the pull-down menu File and selecting the

prompt

is

when

Opening and Closing Vis

Opening Vis

by the

useful

respective block diagram.

g.

file in

copies.

is

the user to identify the

user). Multiple

also possible.

VI

to

Open command.

be opened (where ever the VI

Vis can be opened

The user can choose

to

at

is

This will then

located as specified

any one time. Displaying Vis simultaneously

have both the front panel and the block diagram

48

open on the

screen. This enables the user to see

any changes made

VI

to the

—

in a real

time fashion. For example, a change made to the front panel will result simultaneously in a terminal being created within the block diagram. This

beneficial for de-bugging

is

corrupt or dysfunctional Vis or for adding features (functions, objects, and wiring), in a

manner

that allows the user to see real

Closing Vis applications.

is

The user can use

Close command. The user

time what

is

happening to the VI.

also similar to closing files in

the pull-down File

will then

menu and

most common software

close a VI by clicking the

be prompted to save changes to the VI (provided

changes were made), and then close the VI accordingly. Unless the users specifies a different file path for saving the VI, the

VI

will

be saved in the location from which

it

was opened.

Running Vis

h.

There are two modes for running Vis once a VI has been opened. opening an existing VI, the user can select from two methods run'

mode

or the 'continuous run' mode.

VI executing once

is

single run

mode

run the VI; the 'single

executes the VI once; the

and aborting execution upon completion. The push-

in its entirety

button for a single run

The

to

Upon

displayed as a single arrow (=>) icon and

on the

is

front panel in

the upper left corner (the reader should note that VI can be executed in the block diagram as well, the single run arrow being located in the

same position

on the front

as seen

panel).

The second method

for running a VI, called the continuous run

enables the VI to be run continuously for a specified period of time as user.

Depending on the design of the VI, continuous run mode may

runs of the VI based on a time delay programmed into the VI.

mode,

commanded by

the

result in successive

Once

VI has been

the

placed in a continuous run mode, the VI will continue to run until the user aborts execution

(NOTE: Vis can be programmed

time or samples. In

this situation, the user

execution in accordance with located in the upper

left

or the block diagram.

its

to abort execution after a specified

amount of

need not abort execution as the VI will abort

source code). The continuous run

mode

icon

is

also

corner (right of the single run arrow (=>) icon) of the front panel

The continuous run mode icon

pointing clockwise and counterclockwise.

49

is

displayed as

(^ ~

)

)

with arrows

In addition to the run

modes

icons,

two other icons

are located to the right

of the run modes. These are the 'abort execution' icon and the 'pause' icon; these appear as

(

•)

and

(

|

|

)

respectively.

The

running regardless of what run user to momentarily stop the

abort execution icon push-button stops the

mode

VI

is

execution. This

adjusting the instrumentation device after

once pausing the VI,

selected.

is

VI from

The pause icon push-button allows is

the

helpful if resetting the front panel or

required. Initiating the pause push-button icon

VI continuing

results in the

its

execution from where

it

stopped.

When

running the VI from the block diagram, the user will notice a

'light

bulb' icon to the far right of the pause push-button icon. Initiating the light bulb icon

followed by executing the VI in either run mode, runs the VI in a slow motion manner. In this

slow motion mode, the user

the block diagram. This

not visual

is

when running

most

will see the

VI executing module by module throughout

beneficial in de-bugging errors in

in a real time execution. If an error

terminate at the location (node, object, subVI, point, the user can use the

identify errors

method

and

from executing

on

program code and

correctly.

The user

is

by the appearance of the single run

how to

that are

VI

present, the

is

will

within the block diagram. At this

Show Errors command

to gain information

for de-bugging

etc.)

program code

(under the

Windows menu),

to

correct the errors. This option is the best

for identifying casual errors that prohibit the

able to determine if the

icon. If the (=>) icon is

VI

is

correctly

broken

(

VI

programmed

as such, =/=>), the

user can quickly identify the nature and location of the errors using the light bulb icon run

method

as described above.

GBSTESTBED.VI

4.

a.

Front Panel of GBSTESTBED. VI

Having discussed

LabVIEW

software capabilities and functionality in

general terms, this section addresses the VI developed for use in the

The VI

is

available in the

titled

LabVIEW. This VI

HP 8568B

front panel

GBSTESTBED.VI is

and

is

fixed

spectrum analyzer. As stated previously,

An explanation

of the front panel

is

is

50

all

GPIB

feature

interface with

Vis are associated with both a

the front panel of the

provided below.

Testbed.

from editing by the locking

used for data acquisition through a

and a block diagram. Figure 13

NPS GBS

GBSTESTBED.VI.

gGBSTESTBED.VI Edit

File

Operate

Project

Windows

Help

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JjLJ^J

THESE ARE THE RESPECTIVE OUTPUT AMPLITUDES AND FREQUENCE POINTS FROM THE 8568B SPECAN

^

—

id |523

.1137505000.00

11137850000.00

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P139575000.00

t-63.20

E* save

file

to

name

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file

(read description)

savers name

saved data

tide

saved data comments

1 d

-75.0:

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900000000.0

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Figure 13 Front Panel of the

51

'

1300

nn

GBSTESTBED.VI

The opening the

GBSTESTBED.VI.

HP 8568B

of the

front panel

shown

front panel as

This front panel

what the user

3 is

1

will see

when

first

designed to look very similar to the

is

spectrum analyzer. In the above section of the front panel,

X

the reader will notice a 2

in figure

529 matrix which when the VI

is

executed, displays the

resulting frequency values in the first row, and the amplitude values in the second row.

The sample

shown on

size

the front panel displays 529 readings.

the total sample size at each execution of the

VI

The reader

will note that

1001. For obvious reasons,

is

all

1001

samples are not displayed on the front panel. The program code for initiating 1001 samples

is

The subVI

located in a subVI which is

during execution.

described later in this chapter.

The graphical display the

GBSTESTBED.VI

called by the

is

HP 8568B

is

similar in appearance to

spectrum analyzer. The X-axis

what the user

in frequency (Hz)

is

will see

on

and the Y-axis

displays the amplitude (dB). Prior to the execution of the VI, the user will pre-set the

spectrum analyzer's

start

and stop frequencies based on the expected incoming signal

being evaluated. For example, are using the start

we know

that a satellite signal (multiple transponders)

L-band frequency spectrum (950

frequency would be

amplitude

if

is dictated

950

set at

MHz

to

and the stop frequency

by the output of the spectrum analyzer and

user at the beginning of a sample execution.

incoming signal

1450 MHz), the spectrum analyzer's

is registering,

at

1450

MHz. The

not adjustable by the

is

Therefore, whatever amplitudes the

those same amplitudes will appear on the front panel

graphical display of the VI.

To

the right of the graphical display, the reader will note a series of input

options that the user can elect to

in if desired.

fill

VI can be executed with a save option or

it

The

first

option

is

the save option. This

can be run without saving any of the data. If

the user wishes to save the incoming data, they will depress the save screen. is to

and

PCs

Below

the save push button,

is

the

file

name

push button on the

specification path for

where the data

be saved. This option allows the user to save data to any drive or location desired in

any format desired as hard-drive

as

a

well.

data

[c:\datacollection\testl.dat]. This

For example, file,

(i.e.

Below fairly straight

forward

user

command would

folder datacollection as a data type

software applications

the

file.

This

user elects to save the data to the

if the

is

would

input

something

like

save the incoming signal data to the

especially useful

when using

particular

Matlab) that require specific formats for retrieval of data.

the file

name

—one can

specification block

identify the

52

name of

is

the saver's

name

input. This

the user saving the data

file.

is

In

addition, the user can also

title

comments

the data and input specific

particular test run being conducted.

An example

of such an entry might be

relevant to the

when

testing

is

conducted in poor weather conditions. Adverse weather conditions can greatly affect satellite link

beneficial

performance. Identifying this in the saved data comments section can be

when

looking back

The following file

name

at the

data during analysis and data manipulation.

defines each input function:

(read description)

This is the name of the file where the data will be saved. Data is saved in ASCII format with a header consisting of the "saver's name", "saved data title", "saved data comments", and the date and time the data was collected.

saved data

title

Title

of the data

to

be saved.

saved data comments

Comments on saver's

save to

the data to be saved.

name Name of person(s)

saving

file.

file

This button controls whether data condition where False

b.

is

= do not save

saved to a to file

is

a true/false to file.

Block Diagram of GBSTESTBED. VI

Associated with each front panel of a VI

block diagram

file. It is

and True = save

easily accessible

by

either using the pull

is

the Vis block diagram.

The

down menu under Windows

or

using the 'hot-key' Ctrl E. Both of these methods will allow the user to toggle back and forth

between the front panel and block diagram of the VI.

diagram of the

GBSTESTBED. VI.

It

will

be explained below.

53

Figure 14

is

the block

|

gGBSTESTBED.VI Diagram Fie

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Project

Windows Help

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Figure 14 Block Diagram for the

54

GBSTESTBED.VI

A

explaining

In

GBSTESTBED.VI, we Initially, the

the

programmer can

select the

GBSTESTBED.VI,

GPIB

GPIB

The user can

and depress the

Hz push

CRT

PCMCIA-GPIB

it

selected in the

For now,

slot

the

computer

address 18. This

command prompts

is

command on

the user to select

.

Once

this

compatible with the

and explanation of the

it is

This

Lab VIEW VI GPIB address box, thus establishing the interface is in place, control

and resulting data flows out of the GPIB address box

specific design features this chapter.

signifies the

button to store the address in the instruments memory.

8591 A Read Axis VI. Although

spectrum analyzer,

memory. For

display on the spectrum analyzer. Enter the address

that addressed path

transfer is continuous

that they are identical

change the GPIB address by using the shift-P

40) on the

(1 to

communication over

HP

This box represents

and maintains a path for communication between the device and

easily

same address must be

titled

18.

instrumentation device's

in the

with the instrumentation device on

address

number

number but must ensure

address

the front panel of the spectrum analyzer. Issuing this

a

the

hand corner of the block diagram.

number 18 was chosen. This GPIB address

the

initializes the interface

the PC.

left

behind

design

address between the Lab VIEW VI and the instrumentation device. The

program code as specified

to interface

upper

will start in the

and

process

reader will notice a small box containing the

GPIB primary

in the

thought

the

VI

is

ideally

HP 8568B

and data

into the

used with the

HP

subVI 8591

instrumentation device. The

HP 8591A VI

will be addressed later in

only necessary to understand that this subVI

is

responsible for

generating an array of length 1001, containing frequency or time values in external

engineering units corresponding to each horizontal axis trace point of an

spectrum analyzer. This array

is

used in conjunction with a trace amplitude array to graph

and scale trace data acquired from the instrument device Figure

1

5 is a closer

HP 8568B

(in this case the

view of the GPIB address box and the output wiring

8591 A Read Axis subVI as described above.

55

HP

8568B).

into the

HP

8

GPIB

adress

interface slot

1

|!~-H HFBHRIft

REAJAXK

GPIB Address Box

I

HP8591A Read

I

I

i

Frequency Values

Amplitude Values

i

Axis VI

SUBVI GBSTESTBED.VI

being used as a in

Figure 15

GPIB Address Box and HP

8591 A Read Axis VI

Upon completion of the HP 8591 A subVI subVI and are

then wired to a delay function. The delay function waits a specified

number of milliseconds and number of milliseconds

is

returns the millisecond timer's

modifiable by the user

specifications in the input box.

which

is

routine, the data arrays exit the

common

in

The delay function

LabVIEW

end value. The specified

who can is

enter the desired delay

encapsulated in a case structure

for specifying a data bridge transfer of

any

sort.

The

delay function serves for segmenting data samples into desired sampling rates. For

example,

if

600,000 milliseconds

is

chosen, the VI will collect data from the

spectrum analyzer every 10 minutes and output the data

HP 8568B

to the file specified in the

destination path.

When sent to the

first

the delay function returns the timer's end value, the value

is

Build Array function. The purpose of the Build Array function

then is

to

concatenate inputs (data elements such as the frequency and amplitude values from the

HP 8568B may be

spectrum analyzer), in top-to-bottom order. This function

re-sized

by the user

if desired.

is

re-sizable

and

The Build Array function accepts an array

in

conjunction with a series of elements (frequency and amplitude values). The output array is

a

new

array with appended elements.

56

The new function.

array with

appended elements

is

then forwarded to a Bundle

The bundle function assembles input components

replaces elements in an existing cluster. This function

modified by the user

if desired.

The function serves

to

1

also re-sizable and can be

ready the data elements for export

to the 'save data to file' case structure as seen in the

diagram. Figure

is

into a single cluster, or

lower right corner of the block

6 below shows the transgression of the VI from

its

origin (at the

GPIB

address box) up until the Index and Bundle Cluster Array Function.

"" Build Array Function HP8S91A SubVI

rm

[PBLfl

GPIB Address Box Bundle Function

Index and Bundle Cluster Array

Function

J 16000001

"

©

in its

Figure 16 Transgression Path for the

Before entering the save to

Delay Function embedded

file

own

case structure

GBSTESTBED.VI

case structure, the data elements

cluster form), are submitted to a final function called a Index

(now

in

and Bundle Cluster Array.

This function creates an array of clusters where each element

is

a grouping of the

corresponding elements of the input arrays. For example, given the arrays [1,2,3] and [4,5,6], this

function produces the array [{1,4}], {2,5}, {3,6}]. Likewise, this function

57

is

7

re-sizable.

With regards

data

the

to

being

collected,

this

function

allows

when

corresponding frequency and amplitude values to be matched with reference to their

for

sample was taken.

The new structure.

The reader

array(s) created are

now

ready to enter the save to

will notice that the data entry point

and proceeds downward

to the entry point

is at

file

case

the top of the case structure

of an internal case structure. The data

is first

subjected to a Boolean true false condition. If the user has selected the save option, then

met which

the true condition

is

data. If false, then

no data

is

in turn will allow the save to file case structure to accept

saved to

file.

Let us assume the user has specified a destination

file

path for saving the

frequency and amplitude data from the instrumentation device. The Boolean True/False condition registers a True indication and allows for data transfer into the save to structure. splits

The incoming

data

first

enters an

file

case

Unbundle Function. The Unbundle Function

a cluster (incoming cluster consisting of frequency and amplitude data), into

individual components. In the

incoming cluster

done so

GBSTESTBED.VI,

into the frequency

that the frequency

output to the saved

file

the

Unbundle Function

and amplitude components of the receive

its

the

splits

data. This is

and amplitude components can be formatted correctly

for

annotated in the destination save path. The formatting of the

frequency and amplitude data

is

accomplished via the Format and Append Function(s)

located to the right of the Unbundle Function in the block diagram. Refer to Figure

below which shows

in greater detail the specific area within the block

de-bundling and formatting

is

taking place.

58

diagram where

1

this

N

Samples Formatted "I" times

Format Specification Block

Incoming Cluster

Components of Frequency and Amplitude

Unbundle Function Format and Append Function(s)

Figure

The reader

1

7 Format and

Append Case

will note that along side

Structure

each of the Format and Append

Functions are input boxes where the user can specify what format the data in.

Formatting

criteria

and choices

will

be discussed

reader needs to understand that the data format in the format specification blocks.

indicate that the formatting

is

is

later in this chapter.

dictated

The symbols "N" and

to occur

on

is

to be stored

For now, the

by the input parameters placed

"I" in the upper left

N number of samples (1001)

I

hand corner

amount of times.

This formats the incoming 1001 data points sequentially sample by sample.

While the incoming clustered data structure, so

is

is

entering the internal save case

a series of user input specifications. These user input specifications (as

mentioned before) are the following: •

Saved By header: User

•

Title:

•

Comments: User can

User can

run. For

title

specifies

who (name of file owner)

the output data

input

file.

comments

.

.

i.e.

DVB

data

is

saving the

set.

relevant to a particular data acquisition

example, "Data accumulation conducted during rain showers".

59

file.

stamped on the output

•

Date: Date of data acquisition

•

Time: Time of data acquisition

•

Stimulus and Response: Stimulus

is

is

file.

stamped on the output refers to frequency,

file.

Response to amplitude.

All of these inputs are funneled into a Concatenate Function

which simply

concatenates the inputs into a single header (string) that appears at the beginning of the

output save

file,

and

at the

beginning of every sample.

Of

the six input fields to the

Concatenate Function, the Date and Time parameters are not entered by the user; the

remaining four (Saved By,

Time values

are

Title,

Comments, Stimulus and Response)

are.

The Date and

produced by the Get Date/Time String Function which outputs the date

and time specified by the number of seconds expired since 12:00 am, Friday, January

1904 Universal Time. This

is

a function inherently linked to the

simply replicates the given date and time section of the

VI containing

at

PCs

internal clock

1,

and

execution of the VI. Figure 18 displays the

the input specifications and the Get Date/Time String

Function.

60

TmeK

saver s

name

i

ISAVED

———————— ——— —

.

Concatenate Function

BY:

E23+

E3+ E3+ E3+ E3+

saved data comments |\nTITLE:\s

aE

ES3+

E3+ ES3+

|\nCOMMENTS:\s

E3+

l\nTIMEAs

i

|\nDATE:\s

r ?<

10:21

Get Date/Time String Function

|\n\nSTIMULUSAsRESPONSE\n uiwwuwinjvwifuwijwwwinniuvifuuiiviiwiiuviiuu^^

Figure

1

8 Input Specifications to

Concatenate Function

In looking at figure 18, the reader will notice a series of back-slashes

followed by small case "n" or "s" characters located within the header specification blocks. In the output data

file,

the header reads top-to-bottom starting with "saved data"

and ending with the "date". The back-slash \n signifies to at the

end of the input

field

while

\s

commands

The back-slash formatting commands

LabVIEW

to insert a

new

line

a space after the colon on each input line.

are described later under the Formatting of

Data

section.

The concatenation the

string outputs to the internal case structure containing

Format and Append Functions. The

internal case structure (Figure 17)

concatenated string with the specified data formats for a combined output

proceeds out of the internal case structure to the "output"

61

file

combines the

file

which then

contents block. This block

is

linked by virtue of the save to

is

designed to be used with the

HP 8753B Network

and from disk. However,

strings to

case structure, to the Text File Function VI. This

file

VI

this

analyzer and serves the same purpose in

is

box prompt

exists, the user will

—such

be queried

Analyzer for reading and writing

compatible with the

HP 8568B

spectrum

context as used here. The Text File VI allows

its

a default path and dialog box to be set by the user. special dialog

VI

It

also allows the user to enter a

that if a file is selected to

be written to which already

overwrite the

if s/he really desires to

file.

Figure 19

displays the Text File Function VI.

Enter the name of the file where the data is to be saved.

|file

name

[read description]

dialog box prompt default path (read descript... file

name

read/write (f:read) (read description)

string to be written"--* error in (no error)

string

which was read

""^ error out

IFD:=

read/ write to/from text

file.vi

Figure 19 Text File Function VI Up-close

GBSSUB.VI

5.

Having discussed the elements (function Vis) block diagram, the next VI to be described

is

8591 A Read Axis VI). Recall that

subVI

interface 1

made between

8 as identified in the

the

GPIB

this

HP 8568B

that

the subVI titled is

GBSTESTBED.VI

GBSSUB.VI (same

as

HP

called immediately following the

spectrum analyzer and the

the

GBSSUB.VI

is to

frequency and amplitude values being generated by the is

the

PCMCIA

slot

address

address box.

The primary function of

The subVI

make up

self correcting in that

it

provide a traceable plot of the

HP 8568B

will report errors in

62

spectrum analyzer.

and errors out

—

if errors

are

present in the transgression of data through the block diagram. These types of errors

might be a function of the programming code or the mismatch between frequency and amplitude sampling. The

HP

8591 A subVI generates an array of length 1001, containing

frequency and amplitude values in external engineering units corresponding to each horizontal axis trace point of an

HP 8568B

spectrum analyzer. This array

is

then used in

conjunction with a trace amplitude array (mentioned above), to graph and scale trace data acquired for the instrument.

Front Panel of GBSSUSB. VI

a.

The author

will begin describing the specifics of the

8591 A Read Axis VI) front panel

GBSTESTBED.VI. this front panel

Figure 20

when

is

in

the

same manner as was done with the

the front panel of

accessing this subVI.

63

GBSSUB.VI (HP

GBSSUB.VI. The

user will

first

see

?x

Edit

Cpe:aie

Pic;sd:

Wirfe

Hsip

HH^^^3E13 emu

•••"%'wv,""• '

~.

i

k

*

,1

Iz

"

'•••

\,

'???rrk.ri

z\

nH-^n>

^i

-r.K-rr'Jrj

M

rAi^Ai^'v

1

fesVissssT"!

;

:':

.

1

%- ~&c

—~%* ''"

:':

i|U

:ViVrV£*-'>

^Y!T^£

:";

•.-.-.V.-.i^-

"'.:' jillU^^X'U : ,

J

IM.M.-.i'H;

:J):':':':::'ii"

w~~s* fj

':':

1

_

H[t»l

w*jylt.rU nf£f£n>

,:':

__

.

Figure 20 Front Panel of GBSSUB.VI

64

The upper

left

front panel of the

hand corner, the

error in

GBSSUB.VI

is

very straight forward. Starting in the

code box serves to identify the user of any input errors

generated as a result of sampling mismatch or source code errors.

of the error

in

box

in the top level

is

GPIB

a

address box that serves the

GBSTESTBED.VI.

specified in the top level

To

the immediate right

same purpose

as the address

box

Again, this address must be equivalent to address

GBSTESTBED.VI (GPIB

GBSTESTBED.VI). Looking downward

address

18 in the case of the

in the diagram, the frequency/time

and trace

amplitude columns each with modifiable unit representation, are displayed. In addition, the user can specify frequency units and time units as seen to

left

of the frequency/time

column.

The following

is

a brief description of each input parameter to include

definition of, conditional situations (if applicable), and selection of unit(s):

Frequency Units (Hz:0): Selects the frequency

Definition:

Condition: This setting Unit(s):

O(default)

is

ignored

domain if

units for

Frequency/Time values.

Frequency /Time values contains time domain data.

= Hz.

l=kHz. 2 = MHz. 3 = GHz.

Time

Units (sec:0):

Definition: Selects the

domain

Condition: This setting

is

units for

ignored

if

Frequency/Time Values.

Frequency /Time values contains frequency domain

data.

Unit(s):

(default)

=

sec.

= msec. 2 = usee. 1

Error

In:

Error:

Definition: Indicates the presence of an error condition.

Code

(of error

Definition:

in):

Code

representation for errors in displayed

65

on the

front panel VI.

Instrument driver errors:

Code

Meaning

1210 1220

Parameter out of range

1221

Unable Unable

1223

Instrument identification query failed

225 1 226 1228

Error triggering instrument

Error writing to instrument from

file

1229

Error reading from instrument to

file

1230

Error writing to instrument

1231

Error reading from instrument

1232

Instrument not initialized (no

1234

Error placing instrument in local

1236

Error interpreting instrument response

1239

Error in configuring time out

1240

Instrument timed out

1300

Instrument-specific errors

1

to

open instrument

to close instrument

Error polling instrument

GPIB address) mode

Source: Definition:

The name of the VI

or the routing originating the error message. In the

event of instrument specific errors (code 1300), messages reported from the instrument are also included.

Trace (A:0): Selects the trace to acquire.

Definition:

(default)

Unit(s):

= Trace 2 = Trace 1

= Trace A.

B. C.

Frequency/time values: Definition: This array indicator contains the numeric frequency or time associated with

each of the 1001 points and a corresponding trace amplitude array. The domain of units

is

Time domain. The units within each domain are as Frequency Units and Time Units and control inputs to the VI.

indicated by Frequency or specified

by the

Array of length 1001

:

If the instrument is in a non-zero frequency span,

frequency values. Element

=

stop frequency as dictated

by the

instrument

is

it

contains linearly interpolated

frequency and element 1000

user. If the instrument is in zero span,

linearly interpolated time values. Element

The domain of units

start

and element 1000 =

it

= instrument

contains

instrument sweep time.

indicated by the frequency or time domain. Units within each

66

domain

by the frequency

are selected

units

and time units controls. Units are indicated by

Freq/Time Units.

Frequency or Time domain Definition: The domain of data in Frequency /Time F= frequency domain T= time domain ;

Freq/time units Definition:

The

values.

:

units associated with the data in

String values are

HZ, Khz, Mhz, Ghz,

Trace Amplitude

Freq/Time values.

Sec, msec, and usee.

:

Definition: This array contains the numeric amplitude values of the acquired trace. Units are indicated

by Time and Amplitude

amplitude values in

Units. Array

dBm, dBmV, dBuV,

Volts, or

is

of length 1001 containing trace

W.

Units are indicated by Amplitude

units.

Error out copy

:

Definition: Indicates the presence of an error condition.

Code

(of error out):

Definition:

Code

representation for errors out displayed

on the

front panel VI.

Instrument driver errors:

Code

Meaning

1210

Parameter our of range

1220

Unable

to

1221

Unable

to close instrument

1223

Instrument identification query failed

1225

Error triggering instrument

1226

Error polling instrument

1228

Error writing to instrument from

file

229 1230

Error reading from instrument to

file

Error writing to instrument

1231

Error reading from instrument

1232

Instrument not initialized (no

1

1

234

open instrument

Error placing instrument in

GPIB address) local mode

1236

Error interpreting instrument response

1239

Error in configuring time out

1240

Instrument timed out

67

1300 b.

Instrument-specific errors

Block Diagram of GBSSUB. VI

The GBSSUB. VI block diagram of

this writing will

GBSSUB. VI

is

only be discussed in short

quite complicated and for the purpose detail.

is

a portion of the

block diagram. The figure displays the frequency trace case structure

portion of the source code. For

all

practical purposes, the amplitude trace case structure is

equivalent with the exclusion of unit(s) differentiation.

portion of the total

VI (GBSTESTBED.VI)

exception: Within this block diagram criteria (set at

Figure 21

1001 within the

is

is

68

the user perspective, this

not to be modified with the following

the input

GBSSUB. VI).

From

box

for

modifying the sample size

VMMMHVlNWHWJWtMVWn^^

nmimiimininii

ii

.VlAAVV^WVnAW.VVWtV.'WWA'VW^Mf/VVW/.W.V.V.V.V.V.'

mi

mi

imimiiiiuimiiiiiiiiniimiininmi

'mi

mm

imiiniimiiiiiiiyiiiiiiiiiii

iiiiii'miiiimi

Figure 21 Frequency Case Structure of GBSSUB.VI Block Diagram

In explaining the functionality of the block diagram above, the reader

understand that this VI

GBSTESTBED.VI.

in

and of

itself is

must

a subVI called upon by the top-level

The GBSSUB.VI generates an array of length 1001, containing

frequency, time, and amplitude values in external engineering units, corresponding to

69

HP 8568B

each horizontal axis trace point of an

spectrum analyzer. The array

then

is

used in conjunction with a trace amplitude array to graph and scale trace data acquired

from the instrument. This graphical display

GBSTESTBED.VI on the

front panel portion of the VI.

The block diagram source code

own

internal subVIs.

HP 8591A Handler. VI

and 4)

Initially, the

GBSSUB.VI

for the

executes by calling on

These subVI(s) (which are explained below),

Send Message.VI ,

seen during execution of the top-level

is

HP

HP 8591A

2)

are the following: 1)

Receive Message.VI 3) General Error

8591 A Error Report. VI.

General Error Handler. VI

information for error identification

is

upon which primarily informs the

called

is

VI

user if an input error exists. If an error exists, the

identifies

where

it

derived from the Inputs Error

has occurred. The

pages 65 to 69), and error source, and from an internal error description has provisions to take alternative actions, such as to cancel or

and describe user-defined

an

(GPIB address

Message.VI receives a

GPIB

address.

From

(GBSTESTBED.VI) If

the

HP 8568B

HP

string

from an

trace

for graphical display

HP

an error has occurred, the

HP 8568B

HP 8568B

the

point,

this

(as

GBSSUB.VI on table.

an error

The

status,

table

and

to

8591 A Send Message.VI sends a

spectrum analyzer connected to a

GBSTESTBED.VI).

18 for the

Code

errors.

Provided an error has not occurred, the string to (in this case)

set

Error

in,

described previously under the Error In/Error out specifications to the

test for

its

Conversely, the

HP

GPIB

address

8591 A Receive

spectrum analyzer connected to the same

data

on the

forwarded

is

to

the

top-level

VI

front panel.

8591 A Error Report. VI

spectrum analyzer for two reportable

is

called.

errors: the illegal

This VI queries

command and

hardware broken. These errors are described in pages 65 to 69. The VI polls (and clears) the status byte (error or

no

error)

and

if

the error query

there is no error in the incoming error cluster, then this serial poll until

it

global

VI

is set

(error

=

true),

and

will continue conducting the

locates a reportable error. If a reportable error has taken place, the Error

Report.VI generates an error message to the user.

The user may want scenarios.

Should the user

elect to

portion of the block diagram and closer view of this input

box

is

is

to

modify the sampling

do

so, the input

shown

in Figure

box

is

located in the upper right

22 with the sampling size

provided below in Figure 22.

70

size in different testing

at

1001.

A

^gpg^31§g§^W§g8^pg^

FalseKfmW$3§8^^^W^^%%8ffi$?&

create x-axis array from center and span freqs Input B ox for ing adjusting Sampling Size

?& S.

—

11001

Figure 22 Input box for Modifying Sample Size Criteria

For no other reason should the user have settings in this block

to

manipulate or change the

diagram portion of the GBSSUB.VI. Should the user wish to change

the sample size, s/he can do so using the Tools Palette text entry icon. Place the "small

hand" icon

into the

size required. left

sampling size specification box and then change the input sampling

Complete

the modification

by depressing the push-button

upper

hand comer of the block diagram and then save the VI under a different name. This

will result in a

new

VI with a

different sampling rate.

summarize the complete GBSTESTBED.VI, the best means

In order to to reference the

top-level VI

data fi.ow

version of the

VI Hierarchy

6.

is

VI

hierarchy.

Shown below

(GBSTESTBED.VI) marked by

in figure 23 is the

and then

to the

works

is

and out of the various subVIs and functions

its

way through

the

GBSSUB.VI

transition begins at the

—back

to the top-level

Text File function where the formatting and saving of the acquisition

data takes place. This figure provides the reader with an overview of how the

from

do so

with subsequent sub Vis in a top-to-bottom fashion. The

the wire flow in

top-level and sequentially

to

VI hierarchy displaying the

where applicable. Upon execution of the GBSTESTBED.VI, the

.

in

star, to finish.

71

VI executes

TcpLadGBSIESIEEDM

T©4RleFuilknfo-e^patirg