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ADAS-E project

Project Title   Advanced earth observation Data Acquisition System Evolution
Project Acronym   ADAS-E
Contractor(s)   Alcatel Bell Space NV, Kongsberg Spacetec AS


Project Context


Context   Top

The versatility of an Earth Observation data acquisition station is highly determined by the performance characteristics of its demodulator section. The increasing diversity in the characteristics of the communication links used by advanced EO satellites require throughputs ranging from a few up to several hundreds Mbit/s, as well as the support of a wide spectrum of transmission schemes. Therefore a multi-mission demodulator is the basis to receive multiple satellite missions with the same ground station infrastructure. 
A multi-mission demodulator/decoder can, thanks to the intervened technological evolution, be integrated with other functions, which could expand its capabilities into adjacent functions such as:

  Image Frequency conversion
  Image Data ingestion (with intermediate storage management)
  Image Front-end processing
  Image Modulation & coding (e.g.: for integrated equipment test)


Objectives   Top

The principle project objective is the extension of the ADAS equipment modulation and demodulation capabilities with:

  Image A 4DxTCM encoder for the 8PSK modulator function. This will allow for fullfledged real-time loopback testing of the demodulator 4x8PSK TCM modulation/coding scheme up to frame synchronisation level.
  Image Implementation of a programmable multi-purpose digital FIR filter as an extension to modulator and demodulator signal processing functionality. This FIR filter shall support:
- Bandwidth efficient modulation schemes employing Square Root Raised Cosine (SRRC) baseband pulse shaping (a discrete number of roll-off factors shall be selectable).
- For the demodulator, in case of expected severe Inter Symbol Interference (ISI) due to e.g. imperfect TX filters: Combined (nonadaptive) equalisation and matched RX filtering tailored to a given distortion specification (group delay versus frequency characteristics).The proposed channel filtering and equalization architecture will allow in a future evolution, baseband pulse shaping and equalisation as required for the linear QAM approximation to GMSK.
  Image Study of the implementation of sub-optimal (but acceptable in terms of performance) demodulation of GMSK signals based on the linear QAM approximation to GMSK. Within the scope of this proposal, the GMSK work package shall consist of a technical requirements document and an architectural design document. These documents shall describe:
- specifications of the GMSK transmitter and receiver that can be developed on the ADAS HW platform (performance degradation w.r.t. optimum theoretical receivers, minimum/maximum bit rate, selection of the bandwidth of the Gaussian filter, …)
- how the GMSK functions can be implemented on the existing ADAS HW platform (definition of the extra VHDL building blocks required to do GMSK signal processing)
The actual implementation, testing and demonstration of the GMSK functions on the ADAS are not part of this proposal.
  Image The extension of the ADAS upper data rate limit by integrating in a single acquisition equipment a multi-carrier modulation and demodulation capability for up to 4 carriers (TBC depending on heat dissipation and power consumption), allowing the reception of satellite missions such as Pleiades, ESA Sentinel program, CBERS, HY, … etc.


Architecture   Top

The ADAS-E system is composed of several components (see diagram below).
The basic building blocks that are developed are:

  Image High Data Rate Demodulator (HDRD)
  Image High Data Rate Modulator (HDRM)
  Image X-Band DownConverter (XDBC)
  Image Data Ingest and Front End Processing (DIFEP)
  Image Monitoring & Control function and GUI

Based on these building blocks different equipment configurations will be possible. The ADAS Host Computer is an Industrial PC (IPC), running the Linux operating system. It has an integrated front panel TFT screen and a drawer with a keyboard and pointing device (touchpad, trackball or other). The host computer contains the processor board (SBC - Single Board Computer) and the ADAS specific boards (XBDC, HDRD, HDRM, DIFEP). Either an internal disk, or an external SCSII disk array is used for storage of acquired and processed data.



Capabilities   Top


The ADAS-E system has the following key capabilities:

  Image Supports a wide range of current and planned missions
  Image Processes telemetry from radio frequency (X-band) to Front End Processing (FEP: production of annotated raw data, VCDU, ISP) when in full configuration
  Image Recovers BPSK, QPSK, SQPSK, UQPSK, AQPSK signals (evolution to 8PSK)
  Image Supports a maximum input bit rate of 500 Mbit/sec (QPSK. 250 Mbit/sec I and Q channels)
  Image Saves telemetry data to disk in real time
  Image Distributes telemetry data over a network
  Image Supports loop-back testing
  Image Supports quicklook display


Output   Top

ADAS-E will provide ESA with an integrated earth observation data acquisisition system, able to Processes telemetry from radio frequency (X-band) to Front End Processing and supporting a wide range of current and future missions. The system will be validated in an ESA station using the CRYO, ALOS and ENVISAT missions.

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Page last modified on Tuesday 14 of December 2010 12:19:33 CET by .