First you should build a packet detector which can determine if there is a packet over the air or not. This can be done by detecting channel power change Then you can cut out the part of I/Q stream which just includes one packet. After that you can run frequency demod on the packet. To demod this kind of burst please consider it as an optimizing procedure: you guess the center freq, symbol phase and symbol rate of the FSK burst, making both the freq and symbol timing error minimized.
Peter Lambrechtsen <pe...@crypt.nz> 于2022年7月10日周日 18:20写道： > Hello, > > Excuse my ignorance as I am fairly new to gnuradio but I am trying to > figure out how best to capture a data stream that is in the ISM band that > also has frequency hopping. > > Channel spacing of 25kHz > It has two data bit rates of 62.5bps and 500bps > Starting at 910.5Mhz and going up to 919.975 and in there it has 6 sub > bands of 60 channels it hops between sequentially between the frequencies > in the sub band every 0.4s > > I'm wondering what the best approach would be to capture the data and > figure out when the timing frame was to determine which was the > initial frame as then it should be able to follow the sequential hopping. > > Still trying to work on the blocks to capture all the traffic as I haven't > figured that out yet as I am just working off the specification and trying > to understand the Frequency Xlating FIR Filter to at least capture one FSK > stream to make sure it is sane what I should be receiving, then move to the > frequency hopping. > > Thanks, Peter >
