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
