[Dstar] questions from ZL2DW

[Stuart Bayliss]

Not Derr at all David. Great answers Tony, thanks for such clear answers 
and writing.

cheers

Stuart VK2LSB

Tony Langdon wrote:
> At 07:05 AM 8/27/2008, you wrote:
>> Hello guys
>> please excuse my ignorance here but can someone(s) please give me 
>> your thoughts and observations re dstar.
>
> I'll add my 2 cents worth as a user, though I'm sure the gurus can add 
> more to my reply.
>
>>  I have been subscribed to this reflector for months now and mostly 
>> what I have seen relates to site interconnect problems.
>> Here in ZL we have only one dstar repeater and it's not on a hilltop 
>> yet..........and won't be within my 70cm range when it is.
>> So when it is operational what can those within its range  expect to 
>> do with this dstar stuff, will it be somewhat like a digital form of 
>> IRLP.......or what ?
>
> D-STAR is quite a different beast to IRLP.  While it can do some IRLP 
> like functions, native D-STAR is based on the concept of source 
> routing, where you specify the destination you want to communicate 
> with, the local RF port and the local gateway to use (these parameters 
> are configured into your radio).  Also, D-STAR DV (digital voice) mode 
> has a simultaneous data channel of the order of 1kbps (throughput 
> similar to 1200bps packet radio).  This data channel can be used for 
> chatting, D-PRS GPS data, file transfers and many other uses.
>
> Then there's DD mode (on 1.2 GHz only), which offers 128kbps data over 
> the air.
>
>> Why dstar and not P25 or Tetra ?
>
> Cost, and D-STAR's gateway architecture is much better developed than 
> the other alternatives.  On the global front, several P25 advocates 
> "converted" to D-STAR, because D-STAR has a working worldwide gateway 
> implementation and a rich feature set.  At least one of those now runs 
> a D-STAR gateway.  D-STAR's feature set, while not perfect, is geared 
> towards amateurs, not commercial 2 way radio systems.
>
>> Is there a really good lay mans web site I can go to to read/learn 
>> more about dstar and can someone please comment on the dstar gear 
>> just working as a conventional repeater, how does it sound, how does 
>> the range compare with an analogue repeater on the same band.?
>
> Well, www.dstar.org.au is one place to look, to see how things are 
> going over this side of the ditch.  There's some introductory material 
> there as well.  As for sound, it's not going to go close to a well 
> setup FM repeater - vocoder artefacts are readily apparent.  However, 
> the audio is generally easy to copy, just sounds a bit "unnatural" or 
> "metallic".  Personally, I don't mind it.  As for range, quantitative 
> measurements done by the Utah VHF Society suggest that digital range 
> is very slightly less than FM, but that's taking the 12dB SINAD point 
> as the FM reference, which is quite a noisy signal.  In practice, weak 
> D-STAR signals sound much better than weak FM signals, because D-STAR 
> is noise free down to the digital threshold.  You do get some strange 
> noises (colloquially called "R2D2" ;) ) when the bit error rate starts 
> to climb, before the signal drops out altogether.  Mobile performance 
> can sometimes be a bit affected by multipath, which causes R2D2 
> earlier than you get while stationary.  For this reason, I'd love to 
> see D-STAR on 6 metres one day.
>
>> Does dstar have a future or will it have a successor ?
>
> Hmm, my crystal ball is cloudy, but D-STAR is experiencing rapid 
> growth around the world at this time.
>
>> Are there ever going to be other manufacturers, other than Icom ?
>
> That's something I would love to see.  However, there are other people 
> manufacturing non radio gear (e.g. the DV Dongle) that works with the 
> D-STAR network.
>
>> Like I said please excuse my ignorance but I'm keen to learn and some 
>> of these question may seem a bit derrrr.
>> Many thanks and 73, David Walker (ZL2DW Hastings, New Zealand).
>
> Actually, all good questions, and I hope other people chip in as well.
>
> 73 de VK3JED
> http://vkradio.com
>
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