Tuesday, July 14, 2009

DV Dongle update

Well, I have the DV Dongle working after a fashion, with some interesting discoveries along the way:

  1. You really need to have your application (optionally your applet) JRE set up to be Java SE 1.6. This preference can be achieved in the Mac by using the included "Java Preferences" utility and moving this JRE to the top of the list(s). Note that AFAICT 1.6 is a 64 bit only option (at least it doesn't appear on my early Intel MacBook Pro).
  2. You must start the DV Tool application from the command line, rather than double clicking the JAR file, as is normally possible on the Mac. Apparently the application is quite sensitive to the relative location of some auxiliary binaries. I've played with the JAR packager tool included with the Mac dev tools to try to wrap this conveniently as a Mac OS X application bundle, but so far the correct setting of whatever search path is required to find these binaries has eluded me. I'm sure this is possible though, and presumably an app bundle could be created that just launches the shell script that can usually be used to fire up the app, rather than having the Java launcher load and run the JAR.
  3. On my set up, using a USB headset (at least my Logitech headset) for both input and output audio creates latencies that destroy the audio. You get about a half-second period clicking/drop-out in the audio in this configuration. The simple expedient of turning the output audio to another Mac audio device clears this up so the audio is clean. However...
  4. There is an approximate 2 second delay in audio pumped through the dongle. I have not been able to make this go away. I am running on a super-fast 8-way Mac Pro with loads of spare capacity (idle CPU and low memory pressure).

So, at present, I can connect to gateways and presumably (though I have not tried this yet) transmit audio to a repeater port. The approx 2 second latency though is still a question: is this nominal or degraded performance of the DV system? If the latter, can it be fixed and how?

I'm sure a 2 second latency would not unduly prevent reasonable use of the dongle on the D-STAR network (even if this behaviour isn't quite as designed). Except for timing a break-in, such a delay will only manifest, of course, at the ends of overs and you are supposed to leave plenty of time between overs on the D-STAR system anyway. The lag does sound quite noticeable however when you use a radio to monitor the same port that you have the dongle connected to.

I think my biggest use of the DV Dongle will be to monitor remote repeaters, which I don't think is possible on current radio D-STAR implementations - though I'll be the first to admit that I still have much D-STAR-fu to learn!

No comments:

Post a Comment