IMPLEMENTATION OF A TRANSFORM DOMAIN PROCESSING RADIOMETER FOR DS SPREAD SPECTRUM SIGNALS WITH ADAPTIVE NARROW-BAND INTERFERENCE EXCISER

摘要

This paper describes a receiver designed for the detection of direct sequence (DS) spread spectrum signals in the presence of narrow-band interference. The receiver rejects the narrow-band interference by first performing real-time Fourier transformation of the received signal. This is followed by tracking and excising the narrow-band interference in the transform domain. Finally, the processed signal is inverse transformed and detected by a radiometer. The heart of the implemented receiver is the SAW chirp filters which are used for real-time Fourier transformations. They are all down-chirp devices with 200 MHz center frequency, 60 MHz bandwidth and 60 μs delay. The received (DS) spread spectrum signal can have a bandwidth up to 30 MHz and a maximum duration of 30 μs. The advantage of using this receiver is shown by presenting measured probability of false alarm and detection curves for direct sequence spread spectrum signals with a 5 MHz chip-rate in the presence of both sweeping and single tone CW interference.