Extra transmitting

[kb9mwr]

Shortly after we linked up to DMARC we were wondering why the repeater is transmitting a lot and we don't hear anything on the various talk groups in our radios. At first we thought maybe there were some talkgroups coming through that we didn't know about.

I just started messing with DSD this evening to try and wrap my head around this a bit more.

I doesn't look like voice traffic at all, rather some sort of extraneous data.

-DMR slot1 BS DATA CC=1 Idle
-DMR slot2 BS DATA CC=1 Idle

etc..

I found clues to it all in the spec:
http://www.etsi.org/deliver/etsi_ts/102 ... 10405p.pdf

BS Data refers to signalling used for timing. "If no information is available to transmit in channel 1 and/or channel 2, the BS shall transmit Idle messages to fill out the bursts." "When a MS unit wishes to transmit a data message, it shall wait until the inbound channel is flagged as Channel State Idle (CS_Idle) before it transmits."

Apparently all that extra transmitting of apparently "idle messages" is normal? Funny part is I don't remember it till we linked up. So maybe If I read some more of this cryptic spec, it will continue to become more clear.

[kb9mwr]

From: https://groups.yahoo.com/neo/groups/MOT ... ages/13750

On Mon, May 18, 2015 at 02:00:26PM -0400, Jeff Dale jeff.dale@... [MOTOTRBO] wrote:

> Correct me if I am wrong but the repeater does not switch on and off like
> the mobile does. It broadcasts both slots at the same time, thus only
> needing an amp for regular FM.
>


You are quite correct. If you don't believe me, break out the Thruline and hook it to a mobile - you'll see the needle shuddering on the TDMA pulses and it'll read about half what you expect. Now hook it to a repeater, and it'll be rock steady and show exactly what you'd expect.


The repeaters always transmit a continuous carrier, with idle frames if nothing else. You can hear the tone of the buzz change as it goes from transmitting voice traffic, to "slot in use but quiet", to idle sync frames.


Mobiles, on the other hand, produce the absolute worst possible case scenario AM signal - a bloody great carrier chopped on and off in a 100% modulation squarewave. It's no wonder DMR is hellish for causing RFI! This is exactly why we went over to FM years and years ago - the continuous carrier amplitude doesn't seem to get in and disrupt other equipment nearly as badly. This is why good aerials and minimal feeder radiation is vitally important for mobiles.

[kb9mwr]

Here is what that was all about. A firmware bug!:

From: Mike Swiatkowski
Date: Mon, Oct 12, 2015 at 9:28 PM
Subject: Re: dmr-dmarc Idle transmissions?
To: Steve L


Hi Steve,
This is a classic firmware bug. I logged in remotely and enabled the beacon as we have on all K9MOT peers. This should rectify the issue. You will see a keyup 2s every 2mins. I don't know why Motorola hasn't fixed this odd bug you found but it is the exact same bug as the one we rectified in Milwaukee the same way.

Mike

On Mon, Oct 12, 2015 at 6:49 PM, Steve L wrote:
>
> Here is a raw carrier squelch log of our system:
>
> I haven't had the time to cross reference it with any known voice traffic yet.
>
>
>
> I noticed:
> When it's keyed spewing idle message for what seems like an eternity,
> if you key up and talk, after that it finally rests. (Breaks the
> cycle, at least for a bit)

[kb9mwr]

https://groups.yahoo.com/neo/groups/MOT ... sages/8211

From: MOTOTRBO@yahoogroups.com [mailto:MOTOTRBO@yahoogroups.com] On Behalf Of w2xab@...
Sent: Wednesday, December 18, 2013 7:49 AM
To: MOTOTRBO@yahoogroups.com
Subject: [MOTOTRBO] RE: MotoTRBO Repeater Firmware update R02.30.02


There is a "bug" in the R02.30.02 that effects how we use IPSC. We have the BEACON disabled; but in R02.30.02 there is a bug, the beacon is CONTINUOUS after 60 seconds of inactivity on the repeater if set to DISABLE. Further, if you enable the BEACON and set the interval time to 600 seconds, it BEACONS every 60 seconds.

I have reported both these issues to MotorolaSolutions.

John, W2XAB

[kb9mwr]

From: https://groups.yahoo.com/neo/groups/MOT ... ages/14652
Its not just him

Is it just me or is the beaconing "switch" still broken?
I have a XPR8300 and a XPR8400... both running the latest R02.40.12 firmware and both still cause the transmitter to go key down if you disable beaconing with IPSC enabled.

This problem was identified nearly 2 years ago after a firmware upgrade and it is still malfunctioning today. Yes you can maximize the timer and minimize the duration but it is ridiculous to have a beacon fire when there is no ROAMing on the system.

Any in the know Motorolans have any idea when this will be fixed? It is pretty annoying to have the transmitter key every 600 seconds for no reason... spins the electric meter and likely one less transmission the XPR8300 PA will make.

73
Jon
K1IMD