Safran CORTEX CRT Quantum - Page 275

COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
Ref. DTU 100042
Is.Rev. 5.17
Date: Dec.
03, 2021Sept. 30, 2021
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Page 195
Phase measurements on the major tone are performed at regular time interval (One measurement every 250
ms). These measurements are corrected as described in 3.6.3.4. For each measurement on the major tone is
calculated a « distance » in nanoseconds. The calculation takes into account (ambiguity solving) phase drift due
to spacecraft motion during major tone transmission.
The total duration of the ranging sequence depends on four factors:
 the measurement sampling ratio,
 the minor tone integration time,
 the number of measurements on the major tone,
 the number of minor tones,
 the PLL bandwidth
Assuming that these parameters are:
 Sampling ratio = 1 (no measurement under-sampling),
 Integration duration = 10 * Epoch Period = 10 * Q code length / Chiprate = 2.56 s
(with Chiprate: 1023kcs and Q code: 256 * 1023)
 10 measurements on the major tone
 6 minor tones
 default tone set time (see scenario 1, section 3.6.4.7.1)
 PLL RAU bandwidth in the range 1 to 8 Hz,
The sequence duration is (tone definition tables computation time not included):
 Determination of the beginning of the sequence : < 7 * minor tone integration duration
 Waiting for the beginning of the sequence : < 6 * minor tone integration duration
 Minor tone 1, 2, 3, 4, 5 & 6 : = 6 * minor tone integration duration
 10 measurements on the major tone (0.25 x 9) : 2.25 s
Total sequence duration is < : 50.89 seconds