Tc Demodulation By A Telemetry Chain - Safran CORTEX CRT Quantum User Manual

TC Demodulation by a Telemetry Chain

3.5.4.
For test purposes, it is possible to demodulate a PM or FM-modulated telecommand message using a telemetry
chain (IFR + TMU and associated frame synchronizer). The demodulated message is then automatically bit-by-
bit compared to the transmitted message and any discrepancy reported in the TC acknowledgement message
returned to the TC Client.
This feature is available for TC messages edited at the front panel of the CORTEX CRT Quantum or remote TC
requests (clear or scrambled), received over the LAN.
To perform the test, the IF Modulator output must be looped back onto the IF Receiver through an IF or RF loop
(ensure that the signal level at the IF Receiver input is within the range -5 / -95 dBm). Then, the following
parameters should be set locally or remotely (Refer to the MCS User's Manual):
TMU Frame Synchronizer: Enable
SYN: 0 (the Synchronization Word is supposed to be error-free)
TCU Preamble Length: > 1000 bits (to lock the PSK demodulator and the Bit Synchronizer)
Demod. TM flow: TM-A or TM-B or TM-C (depending on test loop set up)
Demod. Check: ON (next TC request is to be demodulated)
Idle Pattern length: > 0 (to keep the Bit Synchronizer locked)
Once the TC request has been received on the CORTEX CRT Quantum, the synchronization word is
automatically set to the first bits of the transmitted TC message (16, 24 or 32-bit synchronization word,
depending on the TC message length). Parameter Frame/block Size is automatically programmed to the size of
the TC message, rounded up to the nearest byte (if the TC message size is greater than 10 bytes) or
programmed to 10 if the TC message size is less or equal to 10 bytes.
The reconstructed TC message is then compared to the transmitted message. A positive (successful
comparison) or negative (the comparison failed) TC acknowledgement message is returned over the LAN and
the TC transmission (TC request and acknowledgement) reported on the Logging port. The reconstructed TC
message is available on the Telemetry port.
Important: The reconstructed TC message can be displayed on the GUI (Quick Look window). In this case, the
TC message must be long enough to avoid any under-sampling by the Quick Look function (typically, the TC
message duration must be
remote computer or manually program the frame synchronizer.
Should the telemetry chain fail to reconstruct the TC message (wrong loop setting, ...) within N seconds from the
end of transmission of the message by the TCU (N being equal to 480 bits + 1 second), a negative TC
acknowledgement message is returned over the LAN and the TC transmission (TC request and
acknowledgement) reported on the Logging port.
© Safran Data Systems
COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
1 second). For short TC messages, open a connection to the TM port from a
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Safran Data Systems
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Ref. DTU 100042
Is.Rev. 5.17
Date: Dec.
03, 2021Sept. 30, 2021
Page 142