A data collection system installed on the 400 kilowatt X-band transmitter of the Goldstone Solar System Radar is described. The data collection system is built around the off-the-shelf IEEE 488 instrumentation, linked with fiber optics, controlled by an inexpensive computer, and uses software written in the Ada language. The speed and accuracy of the system is discussed, along with programming techniques used for both data collection and reduction

Conroy, B. L.

English

NASA Technical Reports Server

TDA Progress Report 42-95 July-September 1988 
Transmitter Data Collection Using Ada 
B. L. Conroy 
Radio Frequency and Microwave Subsystems Section 
This article describes a data collection system installed on the 400-kilowatt X-band 
transmitter of  the Goldstone Solar System Radar. The data collection system is built 
around off-the-shelf IEEE 488 instrumentation, linked with fiber optics, controlled by an 
inexpensive computer, and uses software written in the Ada language. The speed and 
accuracy of  the system is discussed, along with programming techniques used for both 
data collection and reduction. 
1. Introduction 
The system described in this article is the result of two 
separate goals. The first goal was to  instrument the Goldstone 
Solar System Radar (GSSR) transmitter to  start building a 
base of operating data that could be used for statistical analy- 
sis. The second goal was to demonstrate the feasibility of a 
data collection system that used only readily available, easily 
calibrated instruments. This article is concerned with the 
extent to  which this second goal has been realized. 
The Ada language was chosen for a number of features: 
(1) multitasking is provided within the language, (2) it embod- 
ies a number of software engineering disciplines such as modu- 
larity, strong typing, and levels of abstraction, which will 
result in robust and more maintainable programs, and (3) the 
federal government maintains a standard for the language, and 
enforces conformity to  the standard, which will contribute to  
maintainability of Ada programs. 
II. Hardware Description 
Figure 1 is a block diagram of the entire system, as installed 
at DSS 14. The control computer and one data collection unit 
are located in Room 105. This data collection unit has been 
wired into the Local Control Console (LCC) t o  provide access 
to 26 analog values, 53 interlocks, 40 indicators, and 9 warn- 
ings. The second data collection unit is located in Module 11, 
just below the tri-cone area, and connected to  Room 105 by a 
fiber-optic link. This unit monitors 18 resistive temperature 
detectors (RTDs), 4 turbine flow meters, and 8 paddle-wheel 
flow meters, all of which were added in the radar feedcone 
during the 70-meter upgrade period. 
A. Control Computer 
An IBM industrial AT computer was chosen as the con- 
troller. This computer is similar to  the standard AT, but is 
rack-mounted and provided with an air filter and vibration 
damping mounts for expansion cards. It has an IEEE 488 
interface card, which allows a wide range of instruments to  be 
monitored. 
8. Data Collection Units 
The HP 38528 Data Collection Unit is a rack-mounted card 
case, with local programming capability and a wide range of 
plug-in cards. The cards used in this system include a 5X-digit 
voltmeter (option 44701A), a 5-channel counter (option 
229 
https://ntrs.nasa.gov/search.jsp?R=19890010981 2020-03-20T03:52:54+00:00Z
4471 5A), and several multiplexer cards. Reference 1 contains 
a summary of cards available, and their capabilities. 
C. Fiber Optic 
The data collection unit in the cone area is linked to the 
pedestal by a pair of HP 37204A fiber-optic bus extenders. 
These units are completely transparent to the control com- 
puter, and use internal protocols to ensure error-free data 
transmission. The maximum data transmission rate of 60,000 
bytes per second is adequate for this application. 
111. Software Description 
Figure 2 is a “Booch” diagram of the overall structure of 
the controlling software at a high level of abstraction. This 
style of diagram is introduced in [2] ,  which is an excellent 
introduction to  Ada. The central unit is the HARDWARE- 
DEFINITIONS package, which contains most of the informa- 
tion specific to the transmitter. This package provides a list 
of all the parameters available (an ENUMERATION type), 
functions that return the current value and status of each 
parameter, and an internal task that periodically reads the 
data collection units. Figure 3 is the declaration of the type 
PARAMETER, with explanatory comments. The names chosen 
for the parameters are abbreviations descriptive of the func- 
tion. For example, Filament Time Delay on klystron 1 becomes 
FIL-TD-1 (an interlock) and Alidade Heat Exchanger On 
becomes ALI-HE-ON (a warning because the main heat 
exchanger should be adequate). Some other abbreviations 
used are UC for Under Current, CB for Crow Bar, IGN for 
Ignatron, IL for Interlock, RPA for ReflectedPower Amplifier, 
COLL for Collector, V for Voltage, I for Current, and UA for 
Microamps. 
The GSSR program contains the operator interface. It con- 
tains three display tasks, each of which can be directed to dis- 
play a different view of the data, and a keyboard watching 
task that switches the views based on operator inputs. The 
DATA-LOG package monitors the measured data and writes 
it to  disk. 
A. Utility Packages 
The SCREEN-IO package provides facilities for multiple 
screen windows, each with its own attributes. These windows 
are used by the display tasks to present independent views of 
the measured data. It also provides functions to monitor the 
keyboard. Although they are not used in this application, it 
provides control over the screen modes and graphics capability 
for both color graphics and enhanced graphics adapters. 
The IEEE-488 package provides facilities for sending and 
receiving ASCII or binary data, sending bus commands, serial 
or parallel polling, and detecting service requests. It contains 
an internal task for resource control. This is needed in a multi- 
tasking environment to ensure that different tasks cannot send 
conflicting messages. 
6. Update 
The UPDATE package encapsulates all the information 
about the data collection unit configurations. Several tech- 
niques are used to  minimize the number of transactions on the 
IEEE 488 bus. First is the use of downloaded subroutines in 
the scanners. On startup, this package loads each scanner with 
a program that will take all the required measurements. This 
allows a set of measurements to be taken with the command 
“CALL DOMEAS” rather than a repetition of what measure- 
ments are to be taken. The second technique is the use of 
block transfers in binary rather than individual data values in 
ASCII. This reduces the number of bytes sent by about a 
factor of 3. A third technique is preprocessing the interlocks 
and indicators (which are either 0 or 28 volts) and sending 
only the numbers of the channels that exceed a threshold 
(2 bytes) rather than the actual values (8 bytes). Fourth is 
overlapping the measurement time of one scanner with the 
data transfer time of the other scanner. 
C. Calculated Parameters 
In addition to the parameters measured directly, there are 
a number of calculated ones. Thermal techniques as described 
in [3] are used to calculate the power in the water loads on 
each of the two klystrons and the waster load on the four-port 
power combiner. In addition, a 4-foot section of the wave- 
guide between the power combiner and the feedhorn has been 
calibrated and instrumented for a thermal determination of 
the total power being delivered to the antenna. The time 
remaining in the present cycle (transmit or receive) is calculated 
from the round-trip light time (entered by the operator) and 
the time of the last change in the beam status. This module 
also determines the correct scale factor for the vacuum-ion- 
pump current on each klystron from the range indicators. 
D. Data Log 
The DATA-LOG package contains a set of limits on each 
parameter, and a task that records all analog parameters when- 
ever one or more of the limits is exceeded. 
When the program is started, the operator is prompted for 
the name of the target, the round trip light time (used to cal- 
culate the TIME-LEFT parameter) and a file name for the 
data. The file name is passed to the LOG task, which creates 
the file and writes a header consisting of the data, the target, 
an optional smoothing factor, and the names of the parameters 
that will be recorded. The LOG task waits until all parameters 
have been measured, then writes their initial values to  the data 
230 
file. One of the parameters recorded is the measurement time, 
which time tags the data record. The format used for record- 
ing is Comma Separated Values (CSV) that is, the ASCII 
representation of the values, with commas separating them. 
The decision on when to  record data is based on a “record 
on change” algorithm. The DATA-LOG package contains a 
limit on the absolute value of change for each measured 
parameter. Every time the data is updated, the LOG task com- 
pares the change in each parameter from the last value recorded. 
If the change on any parameter exceeds the limit for that 
parameter, it sets a flag. If no parameter has changed more 
than its limit, the data is kept in temporary storage. When a 
change does occur, two sets of data are recorded: the last 
measurement that did not show a change and the measurement 
that did show a change. This technique simplifies the plotting 
of the data. 
IV. Data Reduction 
Supercalc 4 is used for data reduction. One of its options is 
reading CSV data files, and it allows keyboard macros that can 
import data, set the scales and labels, and plot the data with a 
few keystrokes. Figure 4 is a graph of the transmitter output 
power during a recent experiment. This graph plots the total 
output power (P-TOT), along with output powers of each 
klystron (P-OUT-1 and P-OUT-2). Since all operating 
parameters are recorded, additional graphs, such as beam volt- 
age and drive power, can be produced to  determine the source 
of the variations in the output power. The output power can 
also be supplied to  the scientists for calculation of target 
albedo or cross section. 
V. Results and Discussion 
A. Speed and Accuracy 
The data collection system reads four turbine flow meters 
with 1-hertz accuracy. The actual frequencies range from about 
900 hertz to  1200 hertz, so this is about 0.1 percent of the 
actual reading. There are 18 RTD temperature sensors, which 
are read to  about O.IoC accuracy at a rate of 25 readings per 
second. The system measures 32 dc voltages with %-digit 
precision (100 readings per second) and 120 dc voltages with 
3%-digit precision (160 readings per second). Using the over- 
lapping techniques described above, it makes a measurement 
of every parameter every 3.5 seconds. 
The major limit on the time for a measurement cycle is the 
integration time of the precision voltmeter. Because one scan- 
ner is transmitting its data while the other is making measure- 
ments, an increase in the data transfer rate would not decrease 
the cycle time. The counter card needs 1 second of integration 
time to get 1-hertz accuracy, but it reads all channels simul- 
taneously, and is independent of the voltmeter, so it is not 
limiting the overall speed. 
If necessary, some speed improvement is possible in the 
future by using a higher-speed voltmeter (option 44702A) for 
some of the less critical measurements. This unit has only 
12 bits of resolution (plus sign) and a maximum input voltage 
of 10 volts, but can read up t o  100,000 channels per second. 
6. Problems 
During the initial phases of the development, efforts were 
made to  allow the system to function with bad or missing 
sensors by marking individual data items as “UNKNOWN,” 
but measuring and recording the rest of the data. This effort 
was only partially successful. At present, it can detect and 
allow for problems in the RTD temperature sensors and fail- 
ures of an entire data collection unit. A problem at the card 
level within a data collection unit prevents reading of other 
cards, and a failure of the fiber-optic link prevents reading of 
the local data collection unit. 
C. Open items 
Not yet implemented in the system are: (1) better tech- 
niques of detecting and flagging hardware failures, (2) more 
precise limits on parameters used in the “record on change” 
algorithm, (3) other tools for data reduction, and (4) real-time 
graphical representation of certain parameters. 
231 
References 
[ l ]  Hewlett Packard, HP 38528, Datu Acquisition and ControlSystem Datu Book, 1986. 
[2] G. Booch, Software Engineering with Ada, Second Edition, Menlo Park, California: 
Benjamin/Cummings, 1986. 
[3] B. Conroy, H. Schleier, and T. Tesarek, “Thermal Evaluation Method for Klystron 
RF Power,” TDA Progress Report 42-88, October-December 1986, Jet Propulsion 
Laboratory, Pasadena, California, pp. 91-95, February 15, 1987. 
232 
BUS EXTEND 
HP 37204A 
I I 
I 
I 
LCC 
VOLTAGES 
INTERLOCKS 
INDICATORS 
COMPUTER DATA 
IBM AT IEEE 488 COLLECTIONUNIT e /’ ~ 
IN DUST R I A L HP 3852s 
I 
I 
Fig. 1. Block diagram of data collection system. 
GSSR I SCREEN IO 
I 
I 
I 
WINDOW 
DISPLAY 
A KEY IN 1 
HARDWARE DEFINITIONS 
IEEE 488  I 
Fig. 2. “Booch” diagram of data collection system software. 
233 
ORIGINAL PAGE IS 
OF POOR Q U A L W  
type PARAMETER is ( 
-- analog parameters 
-- Klystron 1, upstairs system 
LOAD-FLOW-1, LOAD-TIN-1, LOAD-TOUT-1, LOAD-TURB-1, 
COLL-FLOW-1, COLL-TIN-1, COLL-TOUT-1, 
BODY-FLOW-1, BODY-TIN-1, BODY-TOUT-1, 
MAG-FLOW-1, WASTE-TOUT-1, 
-- Downstairs system 
COLL-1-1, FIL-1-1, FIL-V-1, MAG-1-1, 
P-OUT-1, P-DRIV-1, P-REFL-1, VAC-1-1, 
RPA-ONE-1, RPA-TWO-1, 
-- calculated parameters 
P-LOAD-1, P-WASTE-1 , 
-- Klystron 2, upstairs system 
LOAD-FLOW-2, LOAD-TIN-2, LOAD-TOUT-2, LOAD-TURB-2, 
COLL-FLOW-2, COLL-TIN-2, COLL-TOUT-2, 
BODY-FLOW-2, BODY-TIN-2, BODY-TOUT-2, 
MAG-FLOW-2, WASTE-TOUT-2, 
-- Downstairs system 
COLL-1-2, FIL-I-2, FIL-V-2, MAG-1-2, 
P-OUT-2, P-DRIV-2, P-REFL-2, VAC-1-2, 
RPA-ONE-2, RPA-TWO-2, 
P-LOAD-2, P-WASTE-2, 
-- Common Parameters, Upstairs 
WG-TURB, WG-TIN, WG-TOUT, 
P-TOT-TURB, P-TOT-TIN, P-TOT-TOUT, 
BODY-I, BEAM-V, BEAM-I, CB-TIME, 
VAC-V , PHASE , VDC-2 8 ,  P-TOT , 
-- Misc 
P-WASTE, -- sum of two waster loads 
TIME-LEFT, -- derived from RTLT 
MEASUREMENT-TIME, 
-- calculated 
P-TOT-CALC, 
calculated parameters -- 
-- Downstairs 
-- Indicators -- Klystron 1 
UA-5-1, UA-50-1, UA-500-1, UA-5000-1, UA-50000-1, -- Vac Ion Scale 
FIL-RAISE-1, MAG-RAISE-1, DRIVE-RAISE-1, 
FIL-LOWER-1, MAG-LOWER-1, DRIVE-LOWER-1, 
-- Klystron 2 
UA-5-2, UA-50-2, UA-500-2, UA-5000-2, UA-50000-2, -- Vac Ion Scale 
FIL-RAISE-2, MAG-RAISE-2, DRIVE-RAISE-2, 
FIL-LOWER-2, MAG-LOWER-2, DRIVE-LOWER-2, 
common -- 
BEAM-READY, BEAM-ON, BEAM-RAISE, BEAM-LOWER, 
S-BAND-DSN, S-BAND-RADAR, X-BAND-RADAR, 
ANT-POS , LOAD-POS , 
HE-ON, MAIN-HE-ON, MG-ON, DRIVE-ON, 
PHASE-0, PHASE-180, IL-OPEN, 
PGM-MODE, COMP-IF-ON, 
Fig. 3. Ada declaration of type PARAMETER. 
234 
-- Warnings 
ALI-HE-ON, AUX-HE-ON, RESIST-IN, RESIST-OUT, 
HE-TANK-LOW, HE-TANK-PRESS, HE-FANS, 
WG-PRESS, TR-FLOW, 
-- Interlocks 
-- Klystron 1 
FIL-TD-1, FIL-UC-1, COLL-OC-1, FOCUS-UC-1, 
REF-PWR-ONE-1, REF-PWR-TWO-1, REF-METER-1, 
ARC-DET-ONE-1, ARC-DET-TWO-1, 
COLL-FLOW-LO-1, BODY-FLOW-LO-1, 
LOAD-FLOW-LO-1, DRIFT-FLOW-LO-1, FIL-FLOW-LO-1, 
VAC-PWR-1, CB-MAG-1, -- Klystron 2 
FIL-TD-2, FIL-UC-2, COLL-OC-2, FOCUS-UC-2, 
REF-PWR-ONE-2, REF-PWR-TWO-2, REF-METER-2, 
ARC-DET-ONE-2, ARC-DET-TWO-2, 
COLL-FLOW-LO-2, BODY-FLOW-LO-2, 
LOAD-FLOW-LO-2, DRIFT-FLOW-LO-2, FIL-FLOW-LO-2, 
VAC-PWR-2, CB-MAG-2, 
ELEVATION, PS-DOOR, PA-DOOR, CB-DOOR, 
TXR-CONFIG, MICROWAVE, CB-TEST, CB-FIRED, 
FAST-BODY, SLOW-BODY, IGN-PWR, BODY-OC, 
DC-OV, DC-OC, PHASE-FAIL, TR-OIL-LOW, 
HV-ZERO, MOTOR-ST, MOTOR-LO, GEN-LO, ALI-HE-OT, 
common -- 
-- other parameters 
OUTPUT-TO, CONFIG, 
TARGET, TIME, DATE, UNUSED, NONE): 
Fig. 3 (contd). 
235 
DATE 1988.06.20 
401 
30( 
z 
d 
B 
0 a
c 
3 a+ 
3 
0 
W 
20( 
1 O( 
TARGET MARS 
I I I I 
rP-ToTAL 
r P - O U T - '  
L P - O U T - 2  
PACIFIC DAYLIGHT TIME (24-HOUR FORMAT) 
Fig. 4. Typical data plot. 
236 


Transmitter data collection using Ada

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