To develop a High Order SCCC demodulator and decoder (SCCC modem) in the ESTRACK TTCP modem to support missions incorporating the ACM modes of the CCSDS-131.2-B recommendation thus increasing data return.

ESA missions with downlink in X-band are limited to 10 MHz of bandwidth and 8.75 Mbps of data, using the current GAIA modulation. GAIA-NIR is requiring higher data rates and it is pushing the limits at X-band.The CCSDS-131.2-B standard defines 27 Adaptive Coding and Modulation (ACM) modes that are intended to allow fine control of information rate in a given bandwidth to optimise data throughput by minimising the required link margin. A variable rate (0.36 to 0.90) Serial Concatenated Convolutional Code (SCCC) encoder is followed by a transmitter which maps 2 (QPSK), 3 (8 PSK), 4 (16 APSK), 5 (32 APSK) or 6 (64 APSK) bits onto each modulation symbol to accommodate steps of the order of 1 dB in link performance whilst maintaining a constant FER over a range of around 20dB.The high spectral efficiency modulations are having up to ~5 Mbps per MHz of available bandwidth that will allow to extend the capability and meet the GAIA-NIR needs.CCSDS spring meeting will analyse a modification of Rec 2.4.17.A to add some ACM modes of coding and modulation in the X-band Space Research portfolio of selectable modulations. This study will first produce and refine the requirements for the SCCC modem. Then the different elements in the modem (i.e. Channel equalizer, APSK demodulator, SCCC coded and auxiliary elements) will be designed and implemented in a prototype. This SCCC modem prototype will be tested against the requirements. The prototype will be designed to allow smooth incorporation of the SW and FW in the TTCP.