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Re: [Discuss-gnuradio] linking Gnuradio and Gpredict ?
From: |
Darren Long |
Subject: |
Re: [Discuss-gnuradio] linking Gnuradio and Gpredict ? |
Date: |
Mon, 24 Nov 2014 19:22:51 +0000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 |
Hi Mike
Alex (the gqrx and Gpredict author) suggested using pyephem to me once when I
asked about this. I did have a little play with it, but haven't done anything
interesting or useful.
http://rhodesmill.org/pyephem/
Darren, G0HWW
On 24/11/14 10:15, Mike Willis wrote:
> I know this is going back a bit but I would like to do the same thing for my
> Gnuradio satellite ground station. I was actually tempted to compile satellite
> tracking into a Gnuradio block. One you could simply use in a flowchart
> without
> any of the messing about with XMLRPC but like my new hexagonal wheel project,
> with active compensatory suspension, it might be better to use what’s already
> there.
>
>
>
> Did anyone do this? And, how difficult would it be in practice to develop a
> native block that either contains predict, or accesses it? Possibly not very
> difficult at all and maybe already done?
>
>
>
> Mike
>
>
>
>
>
> --------------------------------------------------------------------------------
>
> On 22/07/13 12:31, M Dammer wrote:
>
>
>
> Is it possible to link Gnuradio and Gpredict ? I want to use Gpredict as
>
> tracker controlling the antenna position and to pass doppler corrected
>
> frequency data to Gnuradio.
>
>
>
> In a word, yes.
>
>
>
> Can be very simple. I did it by using an XML Server in the flow graph,
>
> and wrote a quick XML client (actually I "stole" most of it from an
>
> example), and sent the doppler info from predict via a variable.
>
>
>
> doppler info was received from predict using some code to query predict
>
> using UDP. I think I just used nc to send the UDP query to predict,
>
> recovered the shift from the reply, and sent it back to the XML Server
>
> running within the flow graph.
>
>
>
> Unfortunately I can't find my actual code right now, but I literally
>
> copied an example, and added the UDP Predict clients bit. It went
>
> something like this pseudo code (Yes, this is a mix of shell,and
>
> python, and you need to re-write the getting doppler from predict yourself,
> but
> you get the idea, and should give you enough)
>
>
>
> import time
>
> import sys
>
> from socket import *
>
> import xmlrpclib
>
> import binascii
>
>
>
> s = xmlrpclib.Server("http://192.168.39.74:8081"
> <http://192.168.39.74:8081%22>;)
>
> infinite=1
>
> while infinite == 1;
>
> # Grab predict doppler using UDP
>
> DOPPLER=`nc -u -s 2 $PREDICTHOST GET_DOPPLER $NORAD_NUMBER`
>
> s.set_doppler_shift($DOPPLER)
>
> time.sleep(1)
>
>
>
> The variable (lets call it doppler_shift) exists in the flowgraph,
>
> and was multiplied appropriately and applied to the centre frequency of
>
> a FIR filter.
>
>
>
> You can pretty much pass any information you want in and out of a flow
>
> graph using a XML Server/Client pair. I've done TX/RX switching, and
>
> am currently working on telemetry decoding/display
>
>
>
>
>
> Iain
>
>
>
>
>
>
>
>
>
>
>
>
>
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>