TT&C Modem

About TT&C Modem

The TT&C-IMBU (Integrated Modem and Baseband Unit) is a TTC Modem (Modulator/Demodulator) proving Telemetry, Tracking, and Command services for operational ground stations.

The same equipment can also be used during spacecraft AIT during transponder, COMS equipment testing or as part of an RF SCOE.

TTC IMBU unit front 3D Celestia-STS C-STS
TTC IMBU RF-Interface unit front Celestia-STS C-STS
TTC IMBU unit back Celestia-STS C-STS

The TT&C provides uplink modulation with frequency sweeping for transponder uplink acquisition. The uplink supports TC uplink services for the PLOP and TC radiation. The TC data can be provided to the modem at Packet, CLTU or serial data/clock level depending on the customer’s system needs. The system is highly extensible and services such as AD/BD TC transmission and TC authentication can also be provided.

The downlink supports single or dual channel TM acquisition with or without baseband processing. Demodulated data can be output to the user as a demodulated serial stream (e.g. RS422 / LVDS) or processed within the modem with Frame acquisition, error correction coding (Viterbi, Reed-Solomon, etc) and the resulting data output to the user or further processed to TM Packet level.

The TT&C-IMBU is controlled and monitored via LAN or using the system’s local GUI. Test functions within the system include closed-loop testing at TM and TC level, BER testing, Doppler Simulation, etc.

The modem also includes Radiometric Processing (Ranging and Doppler Measurements). The modem supports the generation, reception, and processing of ranging signals using the ESA Tone, Code, and PN standards.

The system is highly flexible and allows C-STS to adapt the modem for specific customer requirements.

FPGA based signal processing provides real-time modulation, demodulation and radiometric processing in association with software that allows the system to be used locally via the system GUI or remotely via LAN.

Key Features

  • 2 IF inputs (typically 70MHz)
  • 2 IF outputs (typically 70MHz)
  • Suppressed carrier schemes – BPSK, QPSK, OQPSK, GMSK
  • Remnant carrier schemes – SPL/PM, BPSK/PM (sine/square)
  • ESA Standard, ESA Tone and PN Ranging (T2B, T4B)
  • DSSS modulation and demodulation (configuration dependent)
  • Ranging and Doppler measurements
  • Uplink and downlink generation and acquisition
  • Doppler Simulation and Uplink sweeping
  • Data interfaces via RS422, LVDS or LAN
  • Gigabit LAN for Control and Monitoring via TCP/IP (using RJ45)
  • External Time/Reference inputs, such as 10MHz, PPS and IRIG
  • Built-In Bit Error Rate Transmitter / Receiver
  • Optional baseband processing including Viterbi and R-S
  • TC Plop mode support
  • Remote interfaces such as SLE, EDEN and C&C available
  • Typical data rates 10Mbps down to 7.8125bps

Additional Baseband Processing Information

  • Telemetry and Telecommand processing system (ESA, ECSS, CCSDS)
    • TM Acquisition and Simulation
    • TC Generation and Acquisition
    • Bit Error Rate Tester
  • 24x RS422/LVDS pairs for baseband interfacing
  • Selectable error correction, line encoding/decoding
  • Telemetry Frame and Packet processing to/from bit level
  • Telecommand Packet and CLTU processing to/from bit level
  • Flexible source and destination routing for unit and spacecraft AIT
  • Galvanically isolated FMEA compliant for direct connection to the flight equipment
  • Includes closed-loop testing, TC Echo, Transponder/RF SCOE end-to-end testing
  • Local data generators allow performance testing including error injection
  • Sophisticated error catching, statistics, logging and data archiving
  • Can be used stand-alone or remotely via M&C / CCS

Equipment Details

The system consists of a 19″ 3U hardware platform that is connected to the C-STS Control and Monitoring Software (CMS). The system can be used as a desktop connected with a standard PC or integrated into a 19″ rack with a dedicated server platform.

The TT&C-IMBU provides Spacecraft Compatible, FMEA proven, galvanically isolated interfaces to the spacecraft with up to 24 differential IO pairs allowing connection to OBC (bypass) interfaces, TMTC Front Ends, Transponders and other equipment. Additional interfaces can be used for Network Data Interface Unit (NDIU), Closed Loop connections as well as RF Suitcase applications.

The system uses a highly configurable platform that allows C-STS to readily adapt to specific customer needs.

The optional baseband processing within the TT&C-IMBU performs real-time Frame/CADU and CLTU processing as well including selectable error correction coding and time stamping plus additional test functions such as Bit Error Rate Testers.

The system is available with both classic TTC modem functions to CLTU/Frame layer or as a ‘hybrid modem’ where full TMTC packet processing layers are added.

The software typically offers archiving, logging, local GUI and statistics regarding the modulation, demodulation, TM and TC incoming and outgoing data with counters for both good and bad information e.g. received frames, frames with RS corrections, MCFC errors, VFCF errors, SPSC errors, etc.

The TM Frame viewer allows identification of bit errors and corrections in RS decoded data. The monitors allow TM Frames, TM Packets, TC CLTUs, and TC Segments/Packets to be viewed at a raw hexadecimal level with header decoders.

Support for more advanced functions such as Service A TC and TC Authentication is also available as is support for Space Link Extension (SLE).

The system can be used directly through the local GUI or via the remote (LAN) interface.

The remote interface of the system is configurable by C-STS to meet the needs of the customer RF SCOE, Central Checkout System or Ground station. Many interfaces are available off-the-shelf such as EDEN, C&C and SLE.

The system includes hardware time stamping support through optional interfaces such as PPS, IRIG-B, and IRIG-G.

The systems are highly customizable to fulfill specific spacecraft needs.

Information, specs & downloads

Download TT&C Modem brochure
TTC IMBU Brochure Celestia-STS C-STS

Heritage

C-STS has delivered TTC modem systems both for ground station and EGSE use for major European prime contractors such as AIRBUS, THALES, OHB to support ESA and non-ESA spacecraft missions including Bepi Colombo, JUICE, Euclid, PROBA-V, Galileo, ExoMars, Solar Orbiter, etc.