MotoTrbo Audible Tone Over DMR?

[noloflash]

Our service used to send an audible alert tone, like QCII over the air. Using Digital this seems impossible the XPR7550 series radios (and perhaps all XPR) filter out all audio wave forms (sine waves) except for DTMF and voice.

I'm trying to understand how this works, why it's necessary in digital and if there is a work around to get an audible tone to broadcast.

I could find anything with a search but I imagine this has been discussed, any further information would be appreciated.

 

[sibbley]

Med-E-Vac Ambulance in my neck of the woods sends out a tone set for dispatch over DMR. I don't know how it works, but it does.

 

[noloflash]

Does it sound like DTMF- Telephone keypad tones, that works....

 

[sibbley]

It could be DTMF. I can't say for sure though.

 

[BigEd1314]

I've heard warbles/alert beeps from consoles on DMR, but never any tones. They use the digital group paging function to alert radios, then do the console warble. It sounds like crap, but it makes a noise.

 

[rescue161]

I have a Motorola console that sends any alert and/or QCII tones and they all sound fine. It's a Motorola MC2500 connected to an XPR4550 and an XPR5550. It's also connected to two Desktrac base stations (VHF and lowband). Four radios in total are controlled by one MC2500. Really cool setup.

 

[BigEd1314]

I have a Motorola console that sends any alert and/or QCII tones and they all sound fine. It's a Motorola MC2500 connected to an XPR4550 and an XPR5550. It's also connected to two Desktrac base stations (VHF and lowband). Four radios in total are controlled by one MC2500. Really cool setup.

Tones over digital sound fine? I hear QCII tones over NXDN and P-25 and they do not sound like a normal tone. They are distorted kind of, they sound all "digitally" if that makes sense.

I know on my Kenwood NX5000 stuff, they now have certain tones that now can be sent over digital and they can be used for paging and sound "pure", like over analog. DTMF over NXDN is what they use for alerting the radio, then play the tone, which doesn't sound like a analog version of the same tone.

 

[rescue161]

Transmitting via the console, the tones sound very good in simplex mode. Going through the repeater, they do have that digital sound, but are still easy to hear.

The test tones that I just tried are Alert 1, 2 and 3 from the MC2500 to a VHF XPR4550 and the receiving radio is a VHF XPR7550. The repeater is a VHF XPR8400.

 

[rescue161]

Marine Corps Base Camp Lejeune sends out alert tones on their P25 system and they sound pretty good too.

 

[Forts]

A fire department near me does station alerting over DMR and it works just fine (it's more of a hi-low warble tone though than a QC tone).

 

[JRayfield]

MOTOTRBO radios will pass audio tones just fine. If audio tones are distorted when going through a MOTOTRBO system, then something isn't set up correctly. Possibly the audio levels are just too high and are overdriving the transmitter.

Audio tones typically do not sound good when being sent through a P25 system. Some of the newer radios that use a newer codec may work better, but I don't know for sure. Audio tones that are passed through an 'older generation' P25 system, though, will be severally distorted, as the codecs weren't designed to pass audio tones like that.

John Rayfield, Jr.

 

[PVPD730]

There's a local ambulance service here that utilizes the "Alert 3" tone to notify crews via the MIP5000 console. Sounds pretty clear most of the time.

 

[noloflash]

MOTOTRBO radios will pass audio tones just fine. If audio tones are distorted when going through a MOTOTRBO system, then something isn't set up correctly. Possibly the audio levels are just too high and are overdriving the transmitter.

Audio tones typically do not sound good when being sent through a P25 system. Some of the newer radios that use a newer codec may work better, but I don't know for sure. Audio tones that are passed through an 'older generation' P25 system, though, will be severally distorted, as the codecs weren't designed to pass audio tones like that.

John Rayfield, Jr.

This is not my experience, try holding a mototrbo up to a tone and will not pass to the other radio unless its dtmf.

 

[CarolinasFeedNet]

This is not my experience, try holding a mototrbo up to a tone and will not pass to the other radio unless its dtmf.

If you are just talking about the mic in a portable radio picking it up, the noise reduction is probably killing it

 

[noloflash]

If you are just talking about the mic in a portable radio picking it up, the noise reduction is probably killing it

Somone just explained to me it's because of teh way Digital works with AMBE based vocoder not recognizing anything but voice.(or DTMF)

 

[michaelstephen]

Tones work fine from a console. For example, Check out http://www.avtecinc.com MotoTRBO is able to send the digital Wave specifications to the radios and they translate it locally. It has been explained to me, The consoles don't actually play audio "over the air", they send the Hz frequency, timing, sample rate, etc and the radio puts it together to produce the sound. Not sure if that is part of the DMR standard or a Moto proprietary feature. Whenever I've tried to send an actual WAV recording of tones from the console, indeed it sounds like crap on the receiving radios - the XML spec files sound great.


Sent from my iPhone using Tapatalk

 

[JRayfield]

Not sure why your test didn't work other than maybe the tone level was over driving the vocoder. I've done the exact same thing and it worked fine. I used an app on my smartphone to generate the tone.

John Rayfield, Jr.

This is not my experience, try holding a mototrbo up to a tone and will not pass to the other radio unless its dtmf.

 

[rescue161]

If DTMF works for you, then single tones should work too. Are you trying to send single tones from an external source through the radio's microphone? If so, you are going to have issues, as JRayfield points out, you are probably over-driving the audio into the mic. Try the same test with DTMF without using the radio's keypad DTMF tones. Use a DTMF tone from an external source through the radio's microphone and you probably won't hear the DTMF on the other end. The levels have to be within a certain parameter, hence why my MC2500 works just fine as they are being sent via line-in, not mic audio.

 

[noloflash]

Follow-up, the occurs when trying to play tone through the built in microphone....filters block all tones except for DTMF.

I just injected Audio QCii tones into the accessory port of the XPR5550(transmit radio). The receiver was a XPR7550e. Everything setup for digital simplex. Surprisingly the XPR7550e did an excellent job of re-producing tones no audible distortion could be detected.

Here is how I plan to use it in the the real world. We dispatch using XPR7550
1. the 7550 will send an alert (text) message to the XPR5550
2. using either sound sniffer software and a usb relay from a computer [or the pin26 relay if I can't get the computer to work right] the 5550 will be keyed up and play the sound either from a computer (it's already connected for recording anyway)

Our preliminary tests show that this will work.....
It's a little crazy but now I see there is no reason that I can think of as to why Motorola didn't design the XPR7550 with tone over digital...It looks like it should be able t work.

Am I missing something?