D-Star data stream is like a jpg picture. Only equipment with the jpg "codec" can read it. This comes in a vocoder chip.
APRS (and text with it) GPS info is converted by a TNC to a data stream that goes on through the radio like a bmp picture. Only equipment with the bmp "codec" can read it. Digipeaters have this kind of codec.
The digipeater would know the D-Star data stream was a picture, but would not be able to open it. Ditto for the D-Star. (How am I doing?)
Correct, except one minor detail: APRS data is just plain serial data, that is not encoded. You can actually read it with anything that will display ASCII text data (the easiest way to do it is to connect to the TNC with a computer and read it in hyperterminal). D-Star on the other hand, uses the vocoder chip to encode the data with the AMBE codec it uses. In order to read out that data, you'd have to have a D-Star enabled radio. Minor, but very significant detail.
On the textual diagram, my radio (through the TNC) would write to my GPS (Garmin Etrex): Radio<-->TNC<-->GPS If I got that GPS affixed to my AD92, would it also be able to do that?
The 92AD wouldn't be able to write to the GPS directly, since it doesn't have TNC capability. It does, however, have serial data capability, which allows you to do the low speed data transfer across the network. It's feasible only if you had a computer hooked up to the TNC, which in turn was connected to the radio and GPS. I guess the short answer is, no you can't unless you make it look like any other GPS equipped packet station. The Kenwood is kind of unique in the fact that it has a bunch of bundled capability that releases the need for all of the extra computer and TNC stuff.
Concerning reach:
With my Kenwood, I could reach a digipeater with packets long before I could reach a repeater with voice. Is this true with D-Star? I wonder if now the digital voice will reach just as far as the digital APRS signal/message.
Since D-Star uses narrow band emissions, you are definitely going to see a little more distance out of it. I don't know the specifics since I have not studied it in depth, but from personal experience, I have never been able to hit the analog repeater (which is right next to the D-Star repeater) successfully from my house 35 miles away on my HT, and regularly communicate through the D-Star repeater using the same equipment. (Actually, a lot of factors could invalidate that example, but the same group maintains both systems, so the equipment is somewhat similar on the antenna systems, and what not.) I don't feel comfortable elaborating on the technical aspects of this because I wouldn't want to misinform you. Perhaps there is someone that could that is watching this thread though. I can, however, tell you that you'd get the same coverage using the low speed digital data on D-Star that you do using voice, since they use the same framework to do it.
GPS transmission and repeaters:
My D-Star manual says auto transmission of a GPS message should not be done through the repeaters (simplex only). No GPS message ever? or only with auto transmission?
Ah, here is where it gets a little interesting. Yes, you can transmit the GPS data to the repeater. GPS coordinates embed into the transmission itself if GPS is enabled. Where the DPRS software is installed on gateway computers (actually, the server software is called javAPRSsrvr), the running process on the gateway computer will take the coordinates and ship them over to the APRS networks server. At the time the manual was printed, you would probably hear not to do that because of these reasons:
1) It will add overhead to data to the repeater
2) Icom made no provision in the original specifications to handle the GPS data on the repeater.
DPRS is something that was written by Pete Loveall, AE5PL, to remedy this situation so that the GPS data will have some use besides simplex. If the DPRS conversion software, javAPRSsrvr, is installed on the repeater gateway computer, then your D-Star GPS data will be converted to something readable by the APRS network, since the format for D-Star GPS data, and APRS (TNC2) data are different.
There are a few rules (err, requests, guidelines), however.
1) We're suggesting, and hoping people will follow this rule, to not use the GPS option if you are making a call across the network through the gateway. One reason for this is people with D-Star radios on the other side of the gateway you are coming out on will see these coordinates plotted on their radio, which is really of no use to them locally, and also, you are adding unnecessary overhead to the network when doing so. Using it in local mode is fine.
2) Do not use the beaconing option on the radio when on a repeater frequency. If you set it to transmit GPS coordinates everytime you key down, then this will ensure that you are streaming the coordinates only when active on the repeater, and not just driving around, or, in my case right now, sitting at home (actually, I don't use the GPS option at home for obvious reasons).
In short, though, if there is translation software on the repeater gateway, feel free to transmit GPS to the repeater while talking in local mode. That is why it was built. The manual stating not to is a subsequent consequence of it being printed prior to there being a valid need for it.
DPRS software
It says in another manual: "You can use GPS-A to transmit D-PRS packets to be converted to standard APRS via a repeater or node equipped with D-PRS translation software." Hm-m-m:
"GPS-A" --the radio setting
"D-PRS packets" --the form APRS takes in D-Star? (jpg/horse style)
"to be converted" --something else has to happen
"via a repeater" --if so programmed (how do I know?)
"or node" --? maybe in a computer?
"equipped with D-PRS trans. software" --software. I got lost following the links trying to figure out which one. Nothing I tried worked, and I'm not sure I tried the right ones.
Basically, this is what I went over above. I assume this came out of the DPRS manual? "GPS-A" is the radio setting. "D-PRS packets" are what we call the format that D-Star GPS enabled radios transmit. As mentioned before, they are incompatible with APRS packets and must run through the translation routine to be utilized on the APRS network. As far as if it is actually installed, I *think* it comes with the standard package D-Starusers.org sends out to gateway admins. If you're showing up on our last heard list, then, I believe nothing else is needed. It's not the only place it can be installed, but that's the biggest example that comes to mind. Pete (AE5PL), or Gerry (W5MAY) would be able to elaborate on that.
Basically, a good rule of thumb when trying to figure out if something will work with D-Star is, "Am I trying to interface this with something an analog radio will be connected to?". If the answer is yes, then something else has to happen such as a translation routine, or, quite possibly, we haven't figured out what has to happen yet.
