Re: [Svxlink-devel] SVXlink and hardware DTMF decoder
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From: Tobias B. <sm...@us...> - 2008-02-24 11:46:26
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On Wednesday 06 February 2008 17:05:11 you wrote: > Shipped today, it should arrive middle next week. Hopefully electronics > survives. I think the way you had packaged it, it would survive a trip to the moon ;-) I have now connected your interface to my SvxLink and it seems to work just fine. I had to switch to another radio though since the input/output levels on the radio I was using was too week. On the new radio, I'm using the packet radio port. It's not ideal but it works. I cannot get the yellow DTMF level adjustment LED to light up as described in your documentation. I guess this is due to the weak input level. It detects DTMF just fine though. The interface also let CTCSS tones pass through for both RX and TX. Great! Thanks for providing me with a very nice interface with cables and all. All I had to do was to solder on a DIN-connector (female) for the TRX connection. I have chosen to use the TNC2 standard pinout so I already had a couple of cables ready for different tranceivers. Now for the future :-) The SvxLink interface of my dreams would look something like this: * It would have audio amplifiers on the TRX audio input/output stages to be able to compensate for low audio levels. * It would support two transceivers so that left/right stereo channels could be used. That was my thought with the RX0/RX1 bit in the protocol. Note: The use of left/right stereo channels has not been implemented in SvxLink yet. * It would use USB instead of a serial port. USB audio on the board would be nice also but that will of course make things a bit more complicated. Maybe it's not worth the effort/cost. Support for the second transceiver could be constructed as an add on board. The add on board would have to have it's own audio paths, opto couplers and a DTMF decoder. The rest could be shared (DC/DC conv, CPU, MAX232/FT232, DTMF level adjustment circuit). Of course, the SvxLink system of my dreams would not need an external DTMF decoder but your tests show we are not there yet. Maybe the final problems can be solved with some kind of calibration procedure. We'll see... 73's de SM0SVX / Tobias |