A Case Study in NASA-DoD - The Black Vault

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NOTES TO TABLE C-2 (Cont.)
eThe command decoder processor can be retained for clear uplinks.
However, the Air Force Satellite Control Facility (AFSCF) command format
would have to be compatible with the decoder and new software would
be required. This affects the STPSS.
fThe SGLS ground system can process PCM signals, however, some modification
may be necessary because the ARM uses biphase L Manchester
coding and the STP biphase M. However, the current AEM encoder has no
provision for dual baseband, which may or may not be necessary for small
STP missions run on the AEM. The STPSS dual baseband unit is not directly
substitutable on the AEM because it does not include encoding
provisions. The P72-1, P72-2, and S-3 spacecraft have had PCM encoders
with bit rates of 8, 32, and 16 kbps, respectively. These could probably
be used on the AEM if higher data rates are desired.
gBoeing personnel state that encryption is possible for the AEM transmissions;
there appears to be some question about signal isolation,
however.
hThe optional AEM tape recorder has a larger capacity than STPSS.
'Data formatting on the AEM occurs in the PCM encoder. Timing is
provided by the sequencer timer. There is no item as sophisticated as
the bus controller on the AEM; and for small experiments, it is probably
not required. There should be little impact in setting the sequencer
timer for STP missions. The AEM is not capable of transmitting data
rates as high as the STPSS. Therefore, experiments with real time data
rates over 8 kbps cannot be run on the AEM.
iThe AEM remote command processor is not the same as the STPSS computer.
The AEM processor is used simply for verifying commands and
storing them for future execution. Modifying the remote control processor
for SGLS-type commands should not be a major undertaking because
commands are unique to a given spacecraft and its mission anyway.
kExperimental data on the AEM go directly to the PCM encoder. Data
interface units are not really necessary on the small spacecraft.
LBoeing says that the AEM spacecraft can be modified for SGLS compatability
merely by replacing black boxes.