COMMAND RANGING & TELEMETRY UNIT CORTEX
Is.Rev.
Date:
© Safran Data Systems
This document is the property of
Safran Data Systems
.
It cannot be duplicated or distributed without expressed written consent.
Page 24
1.6.1.4.2. High Bandwidth Telemetry with Sub-carrier
Input
IF Receiver output or Auxiliary input
Demodulation
BPSK, PCM/PM (direct bit synchronization available)
Option: PCM/FM capability (discriminator filter available)
Sub-Carrier Frequency
5 kHz to 2 MHz
Bit Rate
1000 bps to 600 kbps (up to 300 kbps for BP-L code)
1000 bps to 5 Mbps PM/PCM, 1000 bps to 15 Mbps FM/PCM (after
decoding. License-dependant. See § 3.3.1.1 )
Bandwidth
Automatically adjusted to the selected bit rate and sub-carrier frequency
PSK Demodulator & Bit Synchronizer PLL BW (CRT XL Quantum)
3%, 1%, 0.3% or 0.1% of BR
PSK Demodulator & Bit Synchronizer PLL BW (CRT eXplorer)
10%, 3%, 1%, 0.3%, 0.1% ,0.03% or 0.01% of BR
Bit Sync. acquisition range
± 4 × PLL BW if the PLL BW is set to 0.1 or 0.3 % of BR
± 2 × PLL BW if the PLL BW is set to 1 or 3 % of BR
Acquisition threshold (CRT XL Quantum)
Eb/No ≤ 0 dB
-
2 dB for direct NRZ bit sync. (narrowest BW) for symbol rate ≥ 1 ksps
10 dB for symbol rates < 1 ksps at 100 sps
Acquisition threshold (CRT eXplorer)
Eb
/No ≤ -8 dB for 0.03% and Symbol rates > 10 ksps
-
2 dB for direct NRZ bit sync. (narrowest BW) for symbol rate ≥ 1 ksps
10 dB for symbol rates < 1 ksps
Viterbi decoding
Rate 1/2 according to CCSDS 131.0-B-3 (§ 3.3) and 1/3
Constraint length 7.
Viterbi depuncturing
Rate 2/3, 3/4, 5/6, 7/8 according to CCSDS 131.0-B-3 (§ 3.4)
From 1/2 rate punctured code. Constraint length 7.
PCM decoding
NRZ-L/M/S, BP-L/M/S, DBP-M/S, DM-M/S and R-NRZ
BER degradation vs theory
≤ 1 dB if BR < 10 Mbps,
≤ 2 dB if BR < 20 Mbps
≤ 1 dB if BR < 5 Mbps (BP or DM codes)
≤ 2 dB if BR < 10 Mbps (BP or DM codes)
Direct Bit Sync. acquisition time
≤ 150 bits if Bit Sync. Loop BW = 0.1 or 0.3 % of BR
≤ 100 bits if Bit Sync. Loop BW = 1 or 3 % of BR
Eb/No measurement
Yes
