European Space Agency

Study Proposal for a UHF Transceiver

Objectives

The objective of the proposed activity is to conduct a study to investigate specific issues related to a UHF transceiver design based on novel techniques. This transceiver shall satisfy the requirements of UHF-based Telecommand- and Telemetry-transmission to Satellites.

This study work is foreseen to produce all required inputs for a full development proposal as a follow-up activity.

The final aim is to develop a hardware product, which is constituted from modular building blocks so that a high degree of adaptability and customization can be reached.

The proposed transceiver is targeted at small LEO satellites.

Surveys are conducted in order to gather the necessary information for establishing requirements based on user needs and for fitting into the regulatory frame conditions. Further, architectural designs are traded-off and a conceptual baseline is elaborated. The transceiver design is based on a Software-Defined-Radio (SDR).

The high level architecture shows the partitioning between the analogue and digital domain. Whereas the analogue part is relying on traditional technology based on components populating a printed circuit board, the digital part is implemented in a field programmable gate array (FPGA).


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The allocation of functional blocks within the FPGA is shown hereafter:


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Basically the FPGA is in charge of managing all signals on the external bus-interface of the Spacecraft like commands from/to the On-Board Computer, as well as providing the “Digital Baseband Processing”. This includes modulating/ demodulating the Transmit/ Receive-signal up/ down to the IF-level.

Challenges

The definition and trade-off of crucial functions of the baseband processing section (SDR= Software Defined Radio). These functions incorporate signal processing as demodulation and modulation (BPSK, OQPSK and GMSK) as well as the usage of Spread-Spectrum and encryption./p>

Benefits

The solutions currently available in the market include only few products, none of which fully meets the identified needs of future applications for these frequency bands.

The proposed study aims at elaborating solutions for the development of the hardware as follow-up activity to fill up the current gap of this specific market segment, consequently putting LuxSpace in an advantageous position to offer TT&C Subsystems for Small Satellites.

Features

At the start of the study the following key-features were foreseen to be further investigated:

  • Reconfigurable: the transceiver will be a software defined radio, able to be upgraded by firmware uploading. The reconfiguration functionality will involve the operative frequency bands, the modulation schemes (among BPSK, OQPSK, GMSK), the transmitting RF power, the usage of SS and encryption.
  • Spread Spectrum (SS): a Spread Spectrum signal will be implemented to increase the spectrum of the signal and provide protection against jamming.
  • Encryption: encrypted signal will be applied for communicating with the on-board transceiver, this feature avoids the possibility of a 3rd party transmitting a signal with the correct structure and format to ‘mimic’ a genuine TC signal thereby making unauthorized commands to the satellite.

After an assessment of the regulative aspects for space-application on the UHF-band it became evident that only a limited implementation of those key-features will be possible. Namely the Spread-Spectrum feature cannot be fitted into today’s frequency licensing requirements. Also the freeing-up of certain UHF bands due to shut-down of analogue terrestrial broadcast services is not likely to be assigned to Space-communication.

Plan

Kick-Off 31.10.2010
Midterm Review 14.01.2011
Preliminary Requirement Review Dec 2011
Final Review Jan 2012

Current status

Documents for Final Review were delivered and the study has been concluded.

Status date

Friday, March 23, 2012 - 13:04