Digital Radio

Staff Involved: Dr Tim Molteno, Ian Scott

This project is developing an FPGA-based digital radio transceiver. It builds on two previous investigations into Gaussian MSK modulation for bandwidth-efficient telemetry.

Receiver Design

High dynamic range, high-speed sampling of the radio-frequency signal is fed directly into a field programmable gate array (Xilinx Spartan III). The signals are processed entirely digitally, including the demodulation. The output of the receiver is an RS-232 serial signal.

Transmitter Design

The transmitter uses direct digital synthesis of the modulated signal. The data is read from a serial port using a UART inside the FPGA. The data is then used to digitally modulate the signal which is used to drive a high-speed digital-to-analogue converter. Finally the signal is amplified and fed into the antenna.

Proposed Uses

The digital radio is not tied to any particular frequency. However the first proposed use is for telemetry from the UnderDOG project. This will be transmitted on a 13.45 MHz carrier with a bandwidth limited to 12.5 kHz.