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Passive ionospheric sounding and ranging -The G3PLX Project

Reception systems

The G3PLX System (EVMChirp)
Peter Martinez started the chirper project, at a time when the processing capacity of the personal computers was at its limit to digest in realtime the audio samples from the receiver. His system is mainly based on an external digital signal processor, DSP, that completes the heaviest task of filtering the audio 8000 times per second. It also time-marks the received signals and only sends measurements to the PC, at a rate of just over 1000 per second, easily processed by any PC.

The G0TJZ System (ChirpView)
With the advent of somewhat faster machines, withing the acquisition range of those interested in propagation, the need for an external DSP processor was eliminated. Andrew Senior developed ChirpView, a chirp detection and graphing program, based only on the use of a modern PC, with a stereo sound card. As with Peter's system, it makes use of an external GPS to obtain its accurate time references.

Copyright John Coppens, 2003 - mail