Many of you know that I'm experimenting with pulsar detection and
monitoring tools for
Gnu Radio, as part of a larger radio-astronomy toolkit for Gnu Radio.
Pulsars produce narrow pulses with quite fast rise times, with pulse
repetition rates of less than 1Hz
up to tens or hundreds of Hz. The pulses tend to have fairly-fast
rise times.
My pulsar profile monitor uses the audio system to monitor the detector
output of a USRP-based
RF front end. That front-end does broad spectral analysis, and also
produces an 8Khz sampled
audio signal for use by the pulsar profile monitor, which uses epoch
folding.
In order to test the pulsar profile monitor, I have a small program that
produces short pulses, buried
in random noise (just like you'd find with a real pulsar). What I'm
finding is that the displayed pulse
profiles bear very little resemblance to the generated profile, with
ringing and undershoot. What I need
to understand is whether it's the audio subsystem that's ringing, or
the FIR filter that I use in the pulsar
profile monitor.
How to FIR filters react to fast-rise-time pulses? Do they ring like
analog filters?
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