Stuart,
On 14-04-13 06:52, Stuart Longland (VK4MSL) wrote: > On 14/04/13 13:48, Albert Cahalan wrote: >>> I don't understand this. Both the GMSK signal and the voice signal are mono. >> Both signals are mono, so they can fit on a single stereo device. >> One gets the left, and the other gets the right. This means you >> don't need to power two devices and have room for two devices. > In a perfect world, yes, I'd agree with you. It can be done all on one > audio device. > In fact, it can be done with a single mono full-duplex device. Just add > a couple of CD4053s which switch the input and output between headset > and radio along with the PTT. This is extra complexity in the audio > interface. Interesting idea. Once we have the whole setup under control, we can look for this as a next step. However, do keep in mind that the mixer-settings of the two ports (radio and voice) can be quite different; so it might require quite a bit of "magic" needed to get this all running correctly. In the end, it might even be better to get somebody to do a open source design of a raspi / beaglebone / pcduino / ... addon board as radio interface + mic interface. What we need is that that we have a device where people can just plug in a handmic, plug in the other side into the radio (discriminator port) and get going. So, if somebody with better hardware skills then me feel an urge to give this a try, please do drop a message in the list. > USB audio devices with stereo inputs are not nearly as common. Do you > really expect the average user to be able to spot the difference from > the packaging alone? True. When doing experiments, I found out a number of odd things about USB audio-dongles: - some do not support stereo capture - some say they support mono playback, but -in fact- do not - quite a lot of them only support 44k1 and 48k sampling. Dongles supporting 8 Khz sampling are in fact pretty rare As albert has indicated, it would be interesting to create a "supported hardware" page. But I think it is up to "the community" to do this. What I will do is set up a wiki so that everybody can update this information him/herself without my involvement. > I don't see a problem with using two USB audio devices provided the > underlying hardware can support it. Well, today I've done an end-to-end test with two raspberry pi's which did work pretty good, each using two usb audio-dongles. The combination of forceing the speed of the USB bus to 12 Mbps (USB 1.1) and using half-duplex on the audio-dongles seams to do it. PTT-switching is done via GPIO (not ideal but good enough for a start). I just need a couple of days to incorperate the changes I did today into the code on github and write a "installation howto". 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
