The filters in perseus.exe v3.0beta1.
(Jan 23 2011)
Test method.


When the test file is played with perseus.exe the screen may look like figure 1. It depends of course how the parameters in perseus.exe are set.

Fig 1. perseus.exe running sim1.wav.

The loudspeaker output from perseus.exe sounds like this: sim1-pers.mp3 (490728 bytes.) The on-off keyed signal is at a level that is similar to the noise floor level in the beginning and end of the file where the data comes from an old Perseus recording.

The filters are quite good with weak spurious responses. The details of the loudspeaker output are shown in figures 2 and 3 which are waterfall graphs produced by Linrad with sim1-pers.mp3 as the input (before conversion to mp3).

Fig 2.The loudspeaker output from perseus.exe when running the test recording sim1.wav. This waterfall graph is produced by Linrad with the loudspeaker output from perseus.exe as input.

Fig 3.The loudspeaker output from perseus.exe This the same as figure 2 at a 10 times higher waterfall speed. The time when the signal sweeps across the passband is well visible as well as a couple of fairly weak spurs.

The loudspeaker output of perseus.exe on an oscilloscope looks like figures 4 and 5 at different X-axis magnification.

Figs 4 and 5The loudspeaker output from perseus.exe in the time domain when the signal sweeps across the filter.

The spurs are a bit weaker than the on-off keyed carrier and they would be well below the noise with the real hardware. The full AGC recovery from a signal at the maximum possible level is about 0.25 seconds.

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