Hi,
Our local repeater club just ordered the new Yaesu System Fusion DR1-X
repeater. The mobile Yaesu rig that will do C4FM digital is the
FTM400DR and a voice board is available for that model. It will
announce your call when you turn it on and will also tell you the
frequency your tuned to, but it will not tell you much else. C4FM
sounds much better than DStar. I don't know how it compares to DMR, but
anything is better than DStar.
Bob, K8LR, [log in to unmask]
On 3/4/2015 8:57 AM, Martin G. McCormick wrote:
> 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
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