Hi,
While other people are working on adding the c2gmsk modem in FreeDV, I have just uploaded a update of the c2gmsk modem on github: https://github.com/on1arf/gmsk Changes: - there is now a version of the modem based on the c2gmsk API. This modem is in "gmskmodem_api", while the code of the old (non-API based) modem is kept in "gmskmodem_old". - added support for half-duplex audio for the c2gmsk modem and the audio-tools This is needed to deal with the USB issue on the raspberry pi - also a compile-time option to make the modem less strict on the C2ENCAP format (i.e. the format of the codec2 stream exchanged between the audiotool (voice input/output) and the c2gmsk modem). - added some code to deal with linux boards that do not have IPv6 enabled (like a raspberry pi after a fresh install of "weezy raspbian", shame on you! :-( ). - one minor change to the API I do want to add that the code for the reception chain has not been 100 % tested, because I have certain hardware in use for another project; so there may be some changes in the future. This should form the basis for a c2gmsk VHF/UHF modem box based on linux based embedded device (like the raspberry pi, beaglebone, ...) - Only two applications are needed: -> "audiotool" is the application that deals with voice/speech input of the user and codec2 encoding -> "c2gmsk" is the gmsk modem that talks to the radio - any device with two audio input/out ports (like two USB audio ports) and a GPIO port / serial port for switching the radio can be used. a FPU is needed for codec2 encoding/decoding. - between the radio and the modem device, there needs to be a small interface board. This consists out one single capacitor per audio-channel (to block DC bias on the audio-signal) and a diode, a resistor and a transistor to switch the PTT of the radio (add one more capacitor is switching is done via the serial port instead of the GPIO port). I will put an article about this on my blog and some information how to install this on a fresh install of a raspberry pi and two USB audio-dongles("USB bus speed = USB 1.1" trick used to solve the USB lost-packets issue). 73 Kristoff - ON1ARF ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
