Our club had a really good presentation in February by a
couple of members about DMR which is also known in the US as
MotoTRBO pronounced MotoTurbo. I strongly suspect it is the new
and neat thing in amateur radio but it has a lot of growing up
to do yet.

	Look it up in a Google search and there is a lot of
information.

	DMR is an open-source standard which means anybody can
make the gear unlike DSTAR so we will probably eventually see
many models.

	Here's the good and the bad.

	The best hand-held right now is sold by a company in the
United States called Connect Systems. I don't know if that's one
or two words. The radios are made in China but to commercial
specifications and sell for around $300 a piece to business and
public safety agencies. Connect Systems gives hams a really good
price break. The guys who gave the presentation say the radios
are good and solid like a Motorola. They are UHF only and will
do analog FM as well as DMR. I'd love to have one, myself, but
read on 'cause here comes the bad news.

	It's your typical screen toy. There are no voice
prompts, no helpful beeps except for one that tells you if you
are trying to transmit on an occupied channel, absolutely
nothing that makes the radio accessible. There's just a nice
strip of glass across the front.

	The programming software is all Windows, all the time,
your typical bundle of lost opportunity.

	Briefly, here is how DMR works.

	There are two tears of DMR. One is for simplex-type
operation such as what one might encounter in a business of some
kind where the staff carry talkies around for tactical
communication. The other tear is repeater-type operation.

	A repeater can handle two simultaneous QSO's and each
conversation can have a talk group. Think of the old community
repeater systems that used to be common in the commercial world.
Instead of different CTCSS tones, you have different talk group
numbers which is why the loud tone if somebody just transmits,
thinking the repeater is free when there is a conversation on
their time slot that is on a different talk group.

	Local systems are connected to the internet, kind of
like echolink but when you get a talk group going, you tie up
one time slot out of the two available and nobody else can use
the system for that slot unless they want to join the talk
group.

	A UHF DMR repeater has one input frequency and one
output just like an analog repeater but two users can share the
input because their transceivers send packets of audio in bursts
at about 20 bursts per second but the repeater tells each
transceiver when it's turn comes so they both interleave their
packets. It's elegant but I can't imagine it on ten or six
meters due to the time lag over skip distances. It would foul up
the repeater's timing and you'd probably be able to hear the
distant signal but your signals would take too long to get back
to the repeater which would stray in to the other guy's slot.

	I saw a lot of neat technology, here, but since there is
no Linux support, it's the same old same old.

	
Since DMR is an open standard, however, there is more likely to
be something useful later as more people will be making
equipment.

	Sorry for the length of this post, but I figured some
might find it interesting.

	By the way, the audio is very good, similar to P25 if
you have heard that.

73
Martin WB5agz