Space-to-Earth telemetry (TM) links have extensively exploited advanced coding schemes, from convolutional codes to Reed-Solomon codes. The Next Generation Uplink Coding Techniques (NEXCODE) study, funded under the Technology Research Program of the European Space Agency (ESA), aimed at research, design, development, and demonstration of a TC receiver chain for scientific missions, including new channel codes. Agencies and researchers investigated and compared a number of possible alternatives, including binary and non-binary LDPC codes even in the presence of jamming. The schemes were evaluated taking into account the peculiar characteristics of TC links in terms of coding gain and complexity. Commands from Earth to space are sent in the payload of TC transfer frames (TFs). A TF is divided into blocks, each as long as 56 bits and individually BCH encoded. The TC transmission protocol includes an additional mechanism that guarantees a minimum number of symbol transitions to keep symbol synchronization. In acquisition mode, the TC standard [15] specifies the use of a symmetric triangular carrier sweeping procedure with the purpose of locking to the carrier frequency. In this stage, the ground station (G/S) transmits an unmodulated carrier whose frequency is swept around the nominal carrier frequency. Carrier tracking in the baseline receiver is performed with a 2nd order PLL, which is compromised in the DS scenario by the noise reduction versus dynamic range trade-off.
Baldi, M., Bertinelli, M., Chiaraluce, F., Closas, P., Dhakal, P., Garello, R., et al. (2017). State-of-the-art space mission telecommand receivers. IEEE AEROSPACE AND ELECTRONIC SYSTEMS MAGAZINE, 32(6), 4-15 [10.1109/MAES.2017.160079].
State-of-the-art space mission telecommand receivers
Paolini, E.;
2017
Abstract
Space-to-Earth telemetry (TM) links have extensively exploited advanced coding schemes, from convolutional codes to Reed-Solomon codes. The Next Generation Uplink Coding Techniques (NEXCODE) study, funded under the Technology Research Program of the European Space Agency (ESA), aimed at research, design, development, and demonstration of a TC receiver chain for scientific missions, including new channel codes. Agencies and researchers investigated and compared a number of possible alternatives, including binary and non-binary LDPC codes even in the presence of jamming. The schemes were evaluated taking into account the peculiar characteristics of TC links in terms of coding gain and complexity. Commands from Earth to space are sent in the payload of TC transfer frames (TFs). A TF is divided into blocks, each as long as 56 bits and individually BCH encoded. The TC transmission protocol includes an additional mechanism that guarantees a minimum number of symbol transitions to keep symbol synchronization. In acquisition mode, the TC standard [15] specifies the use of a symmetric triangular carrier sweeping procedure with the purpose of locking to the carrier frequency. In this stage, the ground station (G/S) transmits an unmodulated carrier whose frequency is swept around the nominal carrier frequency. Carrier tracking in the baseline receiver is performed with a 2nd order PLL, which is compromised in the DS scenario by the noise reduction versus dynamic range trade-off.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
