[drats_users] Using D-Rats on a reflector

[Dan Smith]

Hi James,

> I was listening to Dan, KK7DS, on the REF002A reflector at around 11:30
> PM EDT.

Ah, very good.  That was literally my first time on a reflector.  It's
pretty neat, but it seems a little fragile, even from a voice perspective.

> The discussion appeared to be about loss of messages with D-Rats
> because people would key on the sending signal and corrupt the
> transmission. I know little about how D-Star functions, but I have a few
> procedural ideas to avoid the issue for now.
> The first problem is that the short messages (not file sending) can be
> successfully sent if the originator would key down to announce a message
> was being sent and hitting send while doing this. It would appear that
> Evans, KD4EFM, does this well with his canned weather reports. The other
> way would be to not let the software send the message until the operator
> is actually keying the radio for a voice transmission (radio not in auto
> tx?).

Yes, you're correct.  Getting the radio keyed up ahead of time and
letting D-RATS slip the data in while you're speaking is probably a
really good way to go.  I think that if you take your radio out of auto
tx mode, then a queued bit of data might go out too quickly when you key
up to make it through the reflector in one piece.

Let me ask you a question.  Even though I think I knew better, I wasn't
always leaving much of a gap between key-down and starting to talk.  Was
I being cut off in the beginning of a voice transmission some of the time?

If using a reflector results in, say, a 2-second period where packets
might get dropped, then I could compensate for this in D-RATS.

> Dan mentioned that file transfers with error detection require the
> software to key the radio when needed. In this case, I don't have an
> answer, but a question. If the originator, W6XXX, wanted to transfer a
> file to W6YYY, would collisions be reduced or avoided if the radio was
> programmed to URCALL:W6YYY by W6XXX through the gateway and then send
> the file? Wouldn't D-Star find W6YYY? 

That's a good question, and I was wondering the same last night.  I
would guess that the way the repeater is linked to the reflector, that
you'd still go to everyone and suffer the same issues.

> I'm not sure if D-Rats can respond
> without some way to hit the call button like on a 91AD.

I'm not sure what you mean here.

> What I'm seeing is everyone is trying to use D-Rats with CQCQCQ like a
> broadcast when I would think that you want to send the message or file
> to a specific station just like APRS.

Well, this works beautifully on simplex of course, and actually makes
D-RATS more useful because it can do its own routing.  However, it's
very different on a reflector.

I've added a knob to let you tweak the number and size of packets that
get sent per round of a file transfer.  Let me add something to scale
the size of the "warm up" header and perhaps a delay setting.  I'll post
a beta and then people can play with it and report back.

-- 
Dan Smith
dsmith#danplanet.com, s/#/@/
www.danplanet.com
KK7DS