Hi, Yes - I found that example but found it a bit complicated to use.
Basically I already plan my satellite recordings using Gpredict so attaching that to my GNU Radio flowgraph seemed like the simple next step. I also thought about using https://github.com/nsat/pypredict to have it all in GNU Radio. Cheers, Wolfgang On Sat, Aug 1, 2015 at 6:33 PM, Iain Young, G7III <g7...@g7iii.net> wrote: > Hi Wolfgang, > > You Wrote: > > On 01/08/15 09:17, Wolfgang Nagele wrote: >> >> Hi, >> >> I've recently needed to correct some satellite signals for Doppler >> shift. I found that there was no easy way to do this yet - so I've > > > Interesting. The way I did it was the following (using predict, rather > than gpredict): > > a) Add a XMLRPC Server block to my flowgraph > b) Write a piece of python glue code which: > i) Gets the normalised doppler info from predict via UDP 1210 > ii) Calculates the correct doppler for the s/c frequency > iii) Sends it onto gnuradio to set a variable, which twiddles > a FIR filter by the correct amount rather than mixing via a multiply > block. > > Here is a version of the whole thing used for tracking Funcube-1 > aka AO-73. I use similar scripts for doppler correcting the NOAA birds > as well, and do have a version which handles multiple spacecraft on one > flowgraph > > > #!/usr/bin/env python > > import sys > import time > import socket > import xmlrpclib > > # Create UDP Socket > predsock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) > > # Create XML Object > s = xmlrpclib.Server("http://localhost:8080";); > > # Get Satellite object or name > s_c = str(sys.argv[1]); > > doppler_msg = "GET_DOPPLER " + s_c > > while True: > # Get Doppler from Predict > predsock.sendto(doppler_msg , ("127.0.0.1",1210)) > doppler_str,predaddr = predsock.recvfrom(24) > # Adjust for correct frequency > dopp_float = float(doppler_str) > dopp_freq = (145.935/100.000)*dopp_float > print dopp_freq , dopp_float > > # Send to grc > try: > s.set_dopp_freq(dopp_freq) > except socket.error: > pass > # Sleep > time.sleep(1) > > > All the Best > > Iain > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
