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II. Mission Support 



A. Planetary Flight Projects 

1. Mariner Mars 1971 Mission Support, R.P.Laeser 

a. Introduction. In the last four issues of this volume, 
functional descriptions of the DSN tracking, telemetry, 
command and monitor systems, which are planned for 
support of the Mariner Mars 1971 Mission, have been 
described. 



There have been two major changes which significantly 
affect the previously described systems. First, the data 
processing configuration in the SFOF has been changed 
by the adoption of configuration C (Fig. 1). Secondly, the 
flow of data in the GCF to and from the DSIF stations 
has been changed by the scheduled replacement of the 
2400-bits/s capability with a 4800-bit/s capability. 

b, SFOF data processing. Configuration C was adopted 
to replace the obsolescent IBM 7044 and 7094 computers 
and to upgrade DSN/SFOF capability to be consistent 
with the requirements of Mariner Mars 1971 and future 
projects. The configuration consists of two parallel IBM 
360/75 computers, electrically connected to the dual 
processor Univac 1108 computer of the scientific com- 
puter facility (SCF). It is intended that the two 360/75's 
be used for real-time processing in a redundant mode — 
one backing up the other. Either one should be more 



than capable of handling all Mariner Mars 1971 real-time 
processing requirements. The 360/75 system will be 
designed to handle analysis programs as well as the real- 
time processing. However, because of schedule constraints, 
most analysis programs will have to be processed on the 
1108. 

A more detailed 360/75 configuration is shown in Fig. 2. 
The 360/75 communicates with the DSIF via teletype 
(through the communications processor), high-speed data 
lines, and the new digital wide-band data line. Keyboard/ 
cathode ray tube input/output devices will be provided 
in the user areas along with computer-formatted digital 
TV displays, computer-reconstructed spacecraft video 
displays, and a computer-driven mission display board in 
the DSN operations area. 

The DSN simulation computer, the ASI 6050, is electri- 
cally connected to the scientific computing facility (SCF) 
Univac 1108, which will perform spacecraft mathematical 
modeling. The SFOF PDP-7 computer performs the off- 
line media conversion tasks. The project-supplied mission 
and test computer (MTC) (Univac 1219/1230 complex) 
remains unchanged, as does the TV processing system. 
However, the TV processing system can receive its data 
from either the 360/75 or the MTC. 



JPL SPACE PROGRAMS SUMMARY 37-60, VOL. U 



COMMUNICATIONS 
PROCESSOR 



REAL-TIME 



ANALYSIS 



SIMULATION 



UNIVAC 
490 



UNIVAC 
490 




MISSION AND 
TEST COMPUTER 



MEDIA CONVERSION 



TV-I 



TV-11 



Fig. 1. SFOF configuration C data-processing system 
for Manner Mars 1971 



PDP-7 







(1) 










SCIENTIFIC 
COMPUTING 
FACILITY 
UNIVAC 1108 










IBM 
360/75 A 














(1) WIDE-BAND 




WIDE-BAND 
INTERFACE 








DATA LINE 




































MISSION 
DISPLAY 
BAND 










' m 








(3) 












































(3) 










TV-1 




























(8) HIGH-SPEED 




HIGH-SPEED 
DATA 
INTERFACE 














DATA LINE 












VIDEO 
















IBM 
360/75 B 
































<\ 






















DIGITAL 
TV 












































COMMUNICATIONS 
PROCESSOR 
UNIVAC 490 


TELETYPE 






TELETYPE 


















^ '"d 




















DEVICE 
SELECTOR 


USER 
COMPLEXES 







































Fig. 2. SFOF Manner Mars 1971 IBM 360/75 
computer configuration 



JPL SPACE PROGRAMS SUMMARY 37-60, VOL. // 



c. Effect of configuration C or DSN systems. A change 
of this magnitude obviously has a major effect on the DSN 
tracking, telemetry, command and monitor systems. In the 
tracking system, the tape interface between the DSN 
editing and original data record (ODR) generation func- 
tions in the 7094, and the project orbit determination 
function in the 1108 has been eliminated. Instead, there 
is now an electrical interface between the 360/75 and the 
1108, with the 360/75 performing the editing, ODR 
generation, and pseudoresidual processing, and the 1108 
performing all other functions, including DSIF prediction 
generation. An additional capability of the configuration 
is to process the high-speed tracking data which will be 
generated by the prototype DSIF tracking subsystem at 
DSS 14. 

The telemetry system has the added capability of pro- 
cessing high-rate data from two spacecraft simultaneously 
as it is received over the new 50-kilobit/s digital wide- 
band hne from DSS 14. The capability of the 360/75 also 
allows generation in near real-time of master data records 
(MDR) for all telemetry data. The exact plans for MDRs 
have not yet been formulated. The new display capa- 
bilities of the 360/75 should be appreciated by all 
telemetry analysts, because silent, high-speed, large- 
volume devices will be provided. 

The changes to the DSN command system are similar 
to those already described. The tape interface between 
the project command generation programs and the SFOF 
terminal of the automatic command transmission system 
will be eliminated and replaced with an electrical inter- 
face, and sophisticated input/output will be provided to 
expedite the command transmission process. 

The DSN monitor system will undergo major physical 
change, but minor functional change as a result of the 
new configuration. The display buffer will be eliminated, 
and all DSN monitor functions will be performed by the 
360/75. 

d. 4800-bits/s high-speed data. A new development, 
the Model 203 modem, is the device which provides this 
expanded capability. It replaces the Model 205 modem 



which operated at 2400 bits/s, and it uses the same physical 
circuits as the 205. With this new capability, the same 
quantity of data can be carried on one half the number 
of circuits. The rest of the GCF high-speed data system 
is not changed: block multiplexers, demultiplexers, and 
error detection encoders and decoders. 

e. Effect of 4800-bits/s high-speed data. All DSN 

systems share the use of high-speed data lines. The total 
high-speed data transmission capacity for Mariner Mars 
1971 will not change. Where each DSS previously inter- 
faced with the SFOF over two 2400-bits/s circuits, it will 
now interface over one 4800-bits/s circuit. However, since 
there will no longer be an artificial barrier between the 
lines, the task of assigning data by type to one of two lines 
will disappear, thereby simplifying software at the DSS. 
The overall reduction in circuit quantity provides a 
simpler and easier-to-operate system. 

f. Other changes. Two other changes are noteworthy. 
Open-loop receivers for support of the S-band occultation 
experiment will be provided at DSS 41 and DSS 62 as well 
as DSS 14. However, real-time digitization will be pro- 
vided only at DSS 14. At the overseas stations, the open- 
loop data will be analog-recorded on FR-1400 recorders, 
and these recordings will be made available to the 
experimenter. 

Three separate DSIF telemetry and command processor 
(TCP) programs are now planned. The first will be the 
standard operations program and will provide command 
processing, data recording, and transmission of one engi- 
neering and one science stream for one spacecraft for any 
allowable combination of spacecraft data rates, except for 
high-rate data of 4 kilobits/s and above; an optional use 
of this program will allow processing of high-rate data 
in excess of 4 kilobits/s when no other processing is 
performed. The second program will provide for play- 
back of TCP recordings after the pass in order to fill in 
gaps in the master data record. The third program will 
be used at DSS 14 only and will provide processing of 
two engineering streams, one from each spacecraft, and 
command processing for one spacecraft. 



JPL SPACE PROGRAMS SUMMARY 37-60, VOL. II