Hi, The key issue is a modem that can pass data through the GSM phone voice codec "channel".
The voice codecs used for GSM phones are difficult channels for data as they are optimised for speech signals. So a special modem must be developed, that encodes data in a voice-like signal that can pass through the GSM voice codec. The SM1000 drivers for the various audio ports already work in full duplex. However there may be a CPU load issue to run full duplex, in which case further code optimisation would be required. CPU load will also depend on the modem used which as discussed above will need to be changed/developed for the GSM phone channel. I'd suggest addressing the modem first, as this is the most challenging aspect of the proposed project. There are some papers on the topic, I don't have any direct experience myself in developing such a modem. - David On 12/11/15 23:32, Nouman Khalid/A-XEN R&D/NRTC wrote: > Hello List, > I am working on sm1000 for secure gsm phone project > just like jackpair. I initially learned to work in the LINUX environment and > built some basic codes for sm1000 and tested them. Then I built sm1000 > firmware of codec2 and tested it successfully. As far as gsm phone is > concerned, is it possible to connect sm1000 with gsm phone directly as > jackpair is doing? I am asking this because mobile phone will also use its > own codec for compression and if we apply an already compressed voice on > audio jack of mobile phone; will it be able to retrieved as encryption will > be added in FreeDV mode? Please guide me how I can make sm1000 work in full > duplex mode? > > > Thanks and Regards > Nauman Khalid > Assistant Executive Engineer > Research & Development – NRTC, Pakistan > Phone: +92-995-666-646/634 > Mobile:+92-3008098569/+923208098569 > Email : [email protected] > Web : www.nrtc.com.pk > > ------------------------------------------------------------------------------ > _______________________________________________ > Freetel-codec2 mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > ------------------------------------------------------------------------------ _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
