Pre Detection Diversity Combining - Safran CORTEX CRT Quantum User Manual

3.3.5.2.2. Pre Detection Diversity Combining

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
PCM Mode with dynamic Bit Rate Switch: a second direct PCM telemetry unit may be connected to the same
DCU output to demodulate another bit rate in the case of dynamic bit rate switch. TMU A has to be set with the
highest bit rate and TMU B with the lowest bit rate. The lowest bit rate has to be a sub-multiple of the highest bit
rate. Hence, the IFRs will remain locked during bit rate switch, the frame synchronizer of the corresponding TMU
becoming locked while the other one becoming unlocked.
Note: a status in the DCU monitoring table indicates which IF Receiver is Channel A and which one is Channel
B.
Polarization 1
PM,FM demodulation
Coherent AM
Non coherent AM
Polarization 2
Polarization 1
PCM/BPSK,
PCM/QPSK,
PCM/OQPSK
or PCM/PM
Polarization 2
© Safran Data Systems
COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
In Video Mode: the DCU has two separate outputs. Output # 1 can be routed to either a
low bandwidth telemetry unit or a high bandwidth telemetry unit with sub-carrier. Output # 2
is available for Tracking processing (DTR). Each DCU output can be separately
programmed to Channel A, Channel B, Best Channel or Combined Channels.
In PCM Mode: the DCU has one output. Output# 1 is connected to a high bandwidth direct
PCM IF receiver.
PRE DETECTION DIVERSITY COMBINING IN VIDEO MODE :
Channel A
A
Predetection filtering
Level measurement
Combiner
Predetection
Signal phase
PLL
alignment
Channel B
B
Predetection filtering
Level measurement
PRE DETECTION DIVERSITY COMBINING IN PCM MODE :
Channel A
A
Predetection filtering
Level measurement
Combiner
Predetection
Signal phase
PLL
alignment
Channel B
B
Predetection filtering
Level measurement
Figure 29: Pre detection Diversity Combining outputs
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Output 1
mA + nB
(m + n = 100%)
Output 2
Output 1
mA + nB
(m + n = 100%)
Safran Data Systems
.
Ref. DTU 100042
Is.Rev. 5.17
Date: Dec.
03, 2021Sept. 30, 2021
To :
IF Demodulation
Video test outputs
Tracking processing (DTR)
To :
IF Demodulation
Video test outputs
Page 56