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From: | Francois Gervais |
Subject: | Re: [Discuss-gnuradio] ASK demodulation help |
Date: | Wed, 9 Apr 2014 17:04:39 -0400 |
Depending on various factors the implementation may vary, but you could probably start with a chain that looks something like this:I/q source -> filter -> AGC -> AM demod (complex to mag) -> scaling for am depth -> m&m clock recovery -> slicer -> do something with the data
Other, more advanced implementations might use correlation for synchronization.-John
On Wed, Apr 9, 2014 at 1:27 PM, Francois Gervais <address@hidden> wrote:
Hi,I'm new to gnu radio and I'm trying to demodulate a 125kpbs ASK signal from a device I have, as a first project. I'm using RTL-SDR as the input device.I'm slowly getting there. I receive the signal, at 2Msample/s, I low-pass filter it to 300khz, I send it through the AM demodulation block and then through the DC blocker.From there I have my signal and it looks fine i.e I could retrieve the information manually by looking at it.Now I think the goal is to somehow synchronize with the bits and re-sample to get 1 sample per bit. This could then be sent to a file. Is that it?At first glance I'm thinking I should have a PLL which ouputs a clock at about 250khz (twice the bit rate) and synchronize the rising edge with every bit transitioning from 0 to 1 so unless I receive only ones ou zeros I should be quite in sync. Then I could toggle a sample every falling edge of the clock which should be at about the middle of the bit.Is this a viable solution? Can it be done with gnuradio? Other alternatives?Thanks_______________________________________________
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