Hallo Marcus,
On 29-07-13 01:44, Marcus D. Leech wrote:
- My first step with GNUradio was to learn a bit more about using it;
so .. do some test.
I wanted to use GNUradio to determine the width of an AFSK signal; so
I started looking for a AFSK modulator / demodulator; to come to the
conclussion I didn't find one.
I looked in the GR source, on CGRAN, using several generic search
engines without look.
Am I missing something here? I would be surprised there is no AFSK
modulator / demodulator in GR as it would mean one cannot do
packetradio or APRS with gnuradio.
(...)
Just found this, it might help:
https://github.com/dl1ksv/gr-afsk
Hmmm. Looks interesting. A good start. :-)
However, it seams I have another problem: it does not build on my system
(ubuntu 12.04 LTS).
It needs gnuradio-runtime and as I currently run gnuradio 3.6.4.1 +
Boost 1.49 build from source, it doesn't have that.
I tried to build 3.7.1 -which seams to include gnuradio-runtime in its
source- but that fails on a number of tests (qa_fir_filter,
qa_freq_xlating_fir_filter, qa_constellation_receiver and
qa_codec2_vocoder).
Grrr! :-(
Also, keep in mind that AFSK is a kind of "double modulation scheme".
To demodulate it, first demodulate the FM-voice using a narrowband
FM demodulator, then run that into a suitaby-configured FSK demod.
AFSK was always a "hack" to allow you to send data over narrowband
FM-voice radios without having to do anything to the radio. So, they
chose
Bell-202 synchronous modem tones, because they'd "fit" in most
narrowband FM-voice radios.
Well, that is exactly the reason I would like to test it out. :-)
We currently do packet/ax.25/aprs at 1200 baud AFSK, which is not that
much less then the 1400 bps needed for codec2. Add a little bit frame
sync-patterns and -perhaps- some FEC, we might end up with 1600.
It would be kind-of-nice to be able to try out DV with standard FM
handhelds without any need to have a radio that does 9k6.
But, this is for me just as much a practicle test and just a way to
getting to know GNUradio. :-)
Cheerio!
Kr. Bonne - ON1ARF
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