I do not know that it needs to be "handled"... The day we have enough D-Star repeaters and users on the air that an out of town DX signal trips mine I will be tickled to death... not complain....Because JRRL did not put an equivalent to CTCSS or DSQ in the system does not make it need repair...
APCO P25 and Smartnet P25 ( as well as EDACS AEGIS ) for the last 10+ years uses a codec/vocoder that is inferior to D-Star (IMBE vs AMBE)... does that make it broken??? No .. just not perfect.... :-) We still use it. We just live with it and work around it.. It DOES mean try and do better in the next generation.. IE P25 Phase II... If that is the greatest failing we have in a totally amateur digital system... it does not seem to be a big issue to me....With 6k25 emissions we can carve up the band pretty tight on adjacents to keep overlap contours to a minimum from adjacent service areas. Sounds like a coordination issue.. not a technological failing... we do it on 12k5's now.. we can do it on 6k25's next... Yes... Icom oversold it.. but 6k25 does quite well as long as you use reasonable dbu contours to protect adjacents from each other or on channel.. Same in commercial when you get to 6k25... Line them up and they do not play nice end to end....The IF filters are what they are and DSP has limits... I had no intention of comparing D-Star to Smartnet or EDACS if that is how you took it... I was saying that the repeaters used in those trunking systems inherently have the modulator and discriminators capable of extracting GMSK ( D-Star) modulation for external processing...no more... I have spent a lot of internet study time, testing etc.. but still less than $500.00 ( of that $350.00 was for the nice little 1U rackmount PC ) converting my Mastr III station... it seems like I am still about $6000.00 in the black compared to converting it to P25... for example... which would sort of be a rational ... albeit expensive comparison :-) I am not trying to push anything on anyone... it is another repeater technology.. and you no longer need to buy the repeater from a sole source.. hopefully that growth might trigger other vendors to offer terminals.. if the market were bigger.. they would be in the game... ignoring it does not help to that end :-) Doug KD8B Kris Kirby wrote: > > > On Fri, 2 Apr 2010, Doug Bade wrote: > > I would be glad to elaborate about D-Star Repeater conversions as > > there are multiple ways to do it now and Any EDACS capable or Smartnet > > Capable repeater would do D-Star as both fundamentally have the parts > > to transmit and receive GMSK type waveforms > > There is one issue that needs to be handled. When a D-Star repeater > "hears" another user on the input for a callsign not it's own, the modem > is captured, and any input packet that starts or is received in the > middle of that transmission is discarded. This, of course, would not be > permitted in the Motorola world; something would have to be done with > the received information, even if a band-opening allowed a remote > digital user to interfere with a digital trunking system's input > channel(s). > > Practically speaking, I think that the earlier data should be thrown > out, and the packet decode restarted with the new signal. Of course, > short of doing SDR and de/re-coding on the fly, this is not a trivial > problem to fix. When your RSSI is measured as BER, it's a different > world. > > -- > Kris Kirby, KE4AHR > Disinformation Analyst > >
