"Key Up" Check-Ins On Digital (DMR, D-STAR,P25, NXDN, etc) Nets

Discussion in 'Digital Radio, DMR, Fusion, Wires, DSTAR' started by KB0OXD, Oct 2, 2019.

ad: L-HROutlet
ad: l-rl
ad: Left-2
ad: L-Geochron
ad: Left-3
ad: L-MFJ
ad: abrind-2


    I thought DMR did send the radio's programmed callsign and ID, but perhaps I am incorrect?

    Maybe a move to M17 would be "helpful". ;)

    But as a technical/rule requirement, only your transmission needs to transmit your callsign. What the repeaters do or not do with that info is their problem.
  2. NC5P

    NC5P Ham Member QRZ Page

    Your radio must have Talker Alias enabled and your callsign must be programmed into it to digitally transmit your ID. That may involve updating firmware to latest version. The problem with DMR is this feature was added later after much of the ham DMR network was established. Even "ancient" P25 can transmit your call digitally, as can D-Star and Fusion.


    If the DMR device sends callsign (which was programmed into the device), then that alone meets FCC rule requirements.
    I suspect, as you mention, perhaps the issue is in the disparities of the gear within same mode, of which I think there is then good argument to be had that the NCS rules take priority, hence the need for verbal callsign.

    It would certainly be much easier in digi land if the mode specs had mandated supporting (and using) callsign that gets pushed ahead of the A-to-D voice. Doesn't dstar and/or fusion mode have 48bits for callsign, which btw seems a bit short on bits (eg, digi gmrs).

    Unfortunately in Rf land under FCC rules, the tech/gear moves fwd (new modes, new codecs, new features), but often times this presents operational issues when old gear is being used with new gear, and vice-versa. Modes/specs need to be fully thought out before the gear is made. Mandating callsign be in on digi up front would have alleviated a lot/most/all of these issues. I mean look, two channel TDMA saves bandwidth, saves power, adds features, yet we still need to waste a little bandwidth (and time) having to do verbals, which seems to be counter-productive in realm digi.
  4. DL2JML

    DL2JML Ham Member QRZ Page

    DMR was not developed for ham radio and probably is used by many more people outside of the ham bands than within. This is why it uses a simple id system and not call signs.


    Well, radio-on-a-chip covers many "bands", so to think DMR digi would not make it into HAM bands is a bit narrow vision on part of DMR code writers.

    But ok, if DMR mode type did not spec out some bits for callsign upon PTT, then technically DMR is not a good mode for HAM bands, well, perhaps I should say, lacking in ability that exploits the benefits of digi.

    But still, technically, under FCC rules, if a DMR radio pushes callsign out front, it's FCC compliant.
  6. DL2JML

    DL2JML Ham Member QRZ Page

    DMR is an ETSI standard and was written to replace NFM, so one would expect that the people at ETSI imagined it would be used on ham bands. Actually, I think about every radio standard has been used on ham bands, hams love to salvage equipment, so the people at ETSI, who are not idiots, would have known.
    Yet they did not introduce a possibility to transmit a call sign (it was only introduced after a few years in the form of "talker alias"). Therefore we must conclude that they did not care.
  7. G8FXC

    G8FXC XML Subscriber QRZ Page

    ETSI is a European organisation and the identification rules for European ham licences seem to be less demanding than those in the US. My UK licence just says :

    "13 Identification
    13(1) The Licensee, or, if this Licence is a Full Licence, then any other authorised person who uses the Radio Equipment, shall ensure that:
    (a) the station is clearly identifiable at all times;
    (b) the Callsign is transmitted as frequently as is practicable during transmissions, unless the specific requirements of Note (g) to the Notes to Schedule 1 of this Licence apply; and
    (c) the Callsign is given in voice or other appropriate format consistent with the mode of operation. "

    So, there is no explicit requirement to start a transmission with your station ID - just to transmit is frequently.

    Talker alias is something that has been spliced onto the protocol by manufacturers for ham users and is an attempt to address the fact that many DMR radios do not have enough memory to store the full ham contacts list. It is not really compatible with the ETSI standard and can seriously confuse some commercial DMR repeaters that have been pushed into amateur service. For a long time, I had to keep it turned off if I wanted to use my local repeater.

    Martin (G8FXC)


    Didn't DMR spec add "talker alias" in 2016? So it's not just a manufacturer add-on, it's actually in the DMR spec, no?

    I am reading a lot about talker alias, but most of it is in terms of doing x-lookup's, like how DNS works. This x-lookup is counterproductive and exposes risk to the system (like a hacker corrupting a x-reference database).

    In my view, all the digi modes (protocol stack of each) should just include a 80bit field for callsign which can be padded with 0's on most significant end when callsign is less than 10 big. This way every PTT the device pushes the callsign ahead of any vocoder bit work.

    Repeaters supporting DMR mode would then just regurgitate that 80bit field.

    This transmit callsign / pass-along method removes any overhead needed by any device to do x-reference work (aka, wasting time), and, removes need to use vocoder to transmit callsign (hard to understand anyways), and, the kerchunk actually becomes useful.

    Where I do see a database x-ref being used is as a feature of a repeater, where the repeater firmware can use this configurable feature to validate a registered radio ID or valid callsign, or even perhaps enforcing a proper radio-ID mapping back to a valid callsign (like a fwd and rev lookup in DNS). This way the repeater ops folks can limit repeater use (filter out rogue HAM's, etc) via various levels of "authorization".

    But to be fair, I am no expert in this area of digi comms (DMR, Fusion, Dstar, etc etc). I just providing chatter from what I am reading & learning.
  9. DL2JML

    DL2JML Ham Member QRZ Page

    It is an optional part of the specification and, typically, is not implemented on the cheapest models as the intended market for these typically do not use a call sign.
  10. N3CLA

    N3CLA XML Subscriber QRZ Page

    Talker Alias is not compatible with Motorola repeaters according to the DMR network folks in my area. It causes dropouts and other signal problems on/with the repeaters.

    I believe it's been pointed out, but the DMR number (radioid.net number) is not FCC-compliant. Maybe one day it will be accepted or DMR will morph to send an actual call sign. Getting gov to adapt to tech vs getting tech to adapt to gov. I suspect I know which way that will go. ;)
    WE4B likes this.

Share This Page