[Freetel-codec2] codec2 modes and sm1000 PTT

[Faisal Saleem]

Hi all,
I am an engineering student and working on a digital voice project. I am impressed by codec2 and sm1000, the freedv adapter. I just got 2 sm1000 modules and built the firmware sm1000.bin successfully. I connected the two sm1000 boards back to back using RIG interface (a cross RJ45 cable). And both sm1000 are talking to each other both in analog and DV modes (fantastic). While studying the code, I've seen that the codec 2 mode is set to 1300. I just changed the codec2 mode to 1600. At 1600 mode the voice quality was not very good compared to 1300 mode and also there was a bit error (error LED constantly on). When I just set the mode to 2400, receiver doesn't receive any thing while transmitter is transmitting. My questions are:
1) Is it enough to change the codec mode in freedvapi.c to change the codec mode or do I need to change some other parameters like Nc, NB etc to run it on 2400 mode without any BER.
2) I want to access the PTT i.e. whenever I press PTT, I want to transmit a custom message first before transmitting the actual voice. How I can do this?

Thanks in advance for your precious help.

Regards,
Faisal

[David Rowe]

Hi Faisal,

1/ You need to change the protocol, bit packing, FEC, number of tones
etc. There may be CPU load issues. Suggest you start with the Host PC
version and test there. Get the entire system working fine on a PC
first, then try porting to the SM1000.

2/ Edit sm1000_main.c where PTT is pressed? Maybe use a state machine
to inject a compressed Codec 2 message before taking audio from the
microphone.

- David

Post by Faisal Saleem
Hi all,
1) Is it enough to change the codec mode in freedvapi.c to change the codec mode or do I need to change some other parameters like Nc, NB etc to run it on 2400 mode without any BER.
2) I want to access the PTT i.e. whenever I press PTT, I want to transmit a custom message first before transmitting the actual voice. How I can do this?
Thanks in advance for your precious help.
Regards,
Faisal
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[Brady O'Brien]

Faisal,

I've not yet done any work to port 2400A or 2400B to the SM1000 or STM32F4.
The FMFSK modem used by 2400B will probably run without issue, as it
doesn't use a whole lot of memory as is, but I'm not sure about FSK. The
big issue I see for you is that 2400A and 2400B operate at a 48Khz sample
rate instead of the 8Khz rate of 1600 or 7.5/8Khz rate of 700B. You'll also
need to move the 2400A/B initialization outside of the #ifdefs in
freedv_api.c for it to build to the SM1000.

Thanks,

Brady O'Brien

Post by David Rowe
Hi Faisal,
1/ You need to change the protocol, bit packing, FEC, number of tones
etc. There may be CPU load issues. Suggest you start with the Host PC
version and test there. Get the entire system working fine on a PC
first, then try porting to the SM1000.
2/ Edit sm1000_main.c where PTT is pressed? Maybe use a state machine
to inject a compressed Codec 2 message before taking audio from the
microphone.
- David

Post by Faisal Saleem
Hi all,
I am an engineering student and working on a digital voice project. I

am impressed by codec2 and sm1000, the freedv adapter. I just got 2 sm1000
modules and built the firmware sm1000.bin successfully. I connected the two
sm1000 boards back to back using RIG interface (a cross RJ45 cable). And
both sm1000 are talking to each other both in analog and DV modes
(fantastic). While studying the code, I've seen that the codec 2 mode is
set to 1300. I just changed the codec2 mode to 1600. At 1600 mode the voice
quality was not very good compared to 1300 mode and also there was a bit
error (error LED constantly on). When I just set the mode to 2400, receiver
doesn't receive any thing while transmitter is transmitting. My questions

Post by Faisal Saleem
1) Is it enough to change the codec mode in freedvapi.c to change the

codec mode or do I need to change some other parameters like Nc, NB etc to
run it on 2400 mode without any BER.

Post by Faisal Saleem
2) I want to access the PTT i.e. whenever I press PTT, I want to

transmit a custom message first before transmitting the actual voice. How I
can do this?

Post by Faisal Saleem
Thanks in advance for your precious help.
Regards,
Faisal

------------------------------------------------------------------------------

Post by Faisal Saleem
Transform Data into Opportunity.
Accelerate data analysis in your applications with
Intel Data Analytics Acceleration Library.
Click to learn more.
http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140
_______________________________________________
Freetel-codec2 mailing list
https://lists.sourceforge.net/lists/listinfo/freetel-codec2

------------------------------------------------------------------------------
Transform Data into Opportunity.
Accelerate data analysis in your applications with
Intel Data Analytics Acceleration Library.
Click to learn more.
http://pubads.g.doubleclick.net/gampad/clk?id=278785231&iu=/4140
_______________________________________________
Freetel-codec2 mailing list
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