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Digital Satellite Modems

PROJECT

DESCRIPTION

PROJECT

DESCRIPTION

Evaluation of IDR and IBS Modems

This contract involved the evaluation of IDR and IBS modems from different manufacturers for a Government customer, who then went on to purchase production quantities of the recommended modems.

Design of Spread Spectrum Modems

Involvement in the design of various types of direct sequence spread spectrum modems, for Government customers. Some of these were for operation in CDMA systems.

Design of a Variable Data Rate High Speed Burst-mode QPSK Modem

The design of this modem was for a Government customer.

DSP-based 64 kBit/s Coded 8-Phase Modem

nvolvement in the design and development of a DSP-based 64 kBit/s coded 8-phase modem, offering significantly greater SCPC traffic capacity than a conventional QPSK modem.

INMARSAT Aeronautical Skyphone Modem

Involvement in the initial development and pre-production prototypes of the INMARSAT Aeronautical Service ground-based modems for the BT Skyphone service.

The Skyphone service was adopted by major airlines including Virgin Atlantic, British Airways, Lufthansa, Lauda, Austrian, Singapore Airlines and others.

60 MBit/s QPSK/TDMA Modems

Performance evaluation and acceptance testing of 60 MBit/s QPSK/TDMA modems for the European Space Agency (ESA). The evaluations were carried out in satellite-loop, with and without various interfering signals.

180 MBit/s QPSK/TDMA Modems

Performance evaluation and acceptance testing of 180 MBit/s QPSK/TDMA modems for the European Space Agency (ESA). The evaluations were carried out in satellite-loop, with and without various interfering signals.

Optimisation of Modem Cover Filters

Optimisation (using computer simulation and measurements) of 180 MBit/s modulator and demodulator cover filters to minimise adjacent channel interference into carrier and clock recovery circuits.

Optimisation of Modem Pulse Shaping Filters

Optimisation (using computer simulation and measurements) of the modem pulse shaping filters for the EUTELSAT ECS TDMA system.

Study of Carrier and Clock Recovery Techniques

Study of carrier and clock recovery techniques for continuous-mode and burst-mode modems at 60 and 180 MBit/s.

Modem Anti-Hangup Techniques

Investigation of anti hangup techniques for burst-mode demodulators, including the use of quenched filters.

Design of a Special Purpose, 140 MBit/s Modem

Involvement in a contract to examine the feasibility of transmitting 140 MBit/s data over 72 MHz bandwidth satellite transponders. This involved considerable computer simulation, as well as the production of the subsystem specifications for the selected modulation & coding scheme.

VSAT Modems

Involvement in the design and development of modems for different types of VSAT applications. See here for details.

Direct Sequence Spread Spectrum Simulator

Involvement in the design and development of a simulator for testing direct sequence spread spectrum demodulators. The unit generated typical spread spectrum signals with a choice of many types of coding.