On Mon, 13 May 2024 15:43:02 -0700
Bill Karsell | K1BP wrote:
I'm still learning DMR. ?When I switch to a DMR talk group on my HT via a
local repeater, I have to kerchunk the repeater before I can hear any
traffic. ?I know that people in the TG can hear me announce my callsign,
which seems rude if they're having a QSO. ?Is it better to kerchunk
without speaking? ?That also seems rude. ?What's appropriate?
That's a good question, Bill. I don't know, for sure, but we can examine it
a little.
Are you sure that others can hear your callsign? I'm sure they can, given
the right set of conditions.
I don't know the exact timing of when the timeslot gets connected to the
TG, but let's try a couple ideas.
The repeater connects immediately upon your key-up. You give your call, and
then release the key. If someone else is talking, then your voice signal
won't get through. At least I think it won't. I've never experienced a
double in DMR, and in fact, I've been effectively kept off a TG by others
keying up quickly and not leaving time for me to connect. I assume this
happens when people are using hotspots. It takes just a little time for the
radio to "handshake" with the repeater, so I'm at a disadvantage. My radio
won't make a connection to the repeater if there's active traffic on the
time slot. AFAIK, it's not possible to double in DMR.
As above, except the repeater connects the TG when you release the mic key.
In this case, your transmission of your call wouldn't go through at all.
The repeater actually requires a short kerchunck to switch the TG, so if you
key up, give your call and release, it doesn't connect, so nobody hears your
call. So in that case, you do the kerchunk, then key up to announce your
call. If another station is transmitting, you won't be able to do that. So
you wait until there's an idle period long enough for you to key up and
announce. I see nothing rude about that. It's no different than tuning to
an FM repeater frequency and waiting until it's clear to announce.
This is just based on my experience with it. I've noticed, for example that
back when I first started using DMR, I could quick-key the DRC machine
(simply talking on the already connected TG). However, that capability went
away, and the vagaries of DMR make it impossible for me to determine what
changed.
I understand your concern, given the FCC requirement to announce your call
when using a frequency. But the norm of kerchunking DMR machines seems to
be an accepted practice among hams. Given the DMR was developed as a
commercial radio system, where the rules are different, I suppose I can see
how they'd design it for the short kerchunk. You'd think the amateurs who
did the work of porting over to our service would consider this.
This would be a good question for K1VAN, if you can find him at a hamfest.
He's one of the people running the NoCoDMR system, and they often have a
table.
Bucky - W0SUN, might know the answer as well.
* There is a scenario where I think a double can happen in DMR, and that's
when using multi-protocol linked systems. There can be timing issues with
syncing everything up, and if the gateways don't handle it properly, a
double might be possible. Just speculation on my part.
--
Jed - KD0YMG - -
"... we have done as much with wireless telegraphy as is likely
to be done."; Sir William Preece, 1891
