Need Help Identifying EMS Dispatch Tones

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jawnah

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Recently, Greenville County EMS switched over to using some sort of new system for toneouts. They were originally only using the system to alert supervisors and had normal EMS units using QCII tone sequences. Now, however, all units seem to be getting dispatched with this toneout. I'd like assistance in identifying what exactly it is.

In addition to EMS using it, Greenville City Fire seems to use something similar. Any assistance you can provide would be great.

I've provided a clip of a tone test for an EMS unit from earlier this evening here: http://www.upstatefire.org/audio/m15tonetest.mp3.

Thanks for your help!
 

jawnah

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Any idea what device(s) use this standard? I just seem to know nothing about this sort of digital paging over a normal UHF channel. I'm just trying to learn more about it.
 

Jay911

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I'm 90% sure as well that that's MDC1200. Rather than tones, it uses a short data burst at 1200 bps. In your agency's case, this is likely used to directly cause the radio receiving it (sounds like either 2 or 3 radios in Medic 15) to make noise (beeps/tones/alerts) themselves. Because those alert tones would be generated by the end user's radio(s), you won't hear them.

Explained a little more in-depth: let's say there are 2 radios issued to Medic 15, one for each paramedic. Each radio has its own unique ID, generally 4 hexadecimal digits long (0-9 and A-F), i.e. 1234 or 9A7C or any such combination. The MDC1200 alerting, instead of a long pair of tones (minimum 4 seconds long per pair, usually), uses a very short data burst. Instead of having to listen for the full set of audio tones, the radio is only listening for its MDC1200 unique ID. When it hears it, it knows to beep or chirp or sound a siren or make some other attention-getting signal to the user.

The added benefit of MDC1200 in many systems is that you can also use it as a radio identifier when the radio is transmitting. Either before or after a unit in the field talks, do you hear a similar data "squawk" as the one you're hearing when alerting is happening? If you do, that means they are using this feature as well, which is known as PTT ID (push to talk identification).

Currently, no scanners support decoding MDC1200 data bursts, and the speculation is because nobody has really clamored for the support to be added - because the ability to decode it is out there. If you search Google for a program called "WinMDCd", you will find a small application you can run on your computer. With an audio cable plugged in to your scanner and the line-in jack on your computer, you can decode the MDC1200 bursts and display the IDs as they come across the radio channel.
 

jawnah

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Jay,

Thanks for the information. I was at least able to learn that they are using that signaling for the radio transmissions themselves. They actually have the unit ID matching to the MDC1200 unit ID field, so I can see what unit is transmitting data. Unfortunately, the alert strings don't trigger anything in WinMDCd right now. They sound close but are slightly different.

In each instance when an "alert" is sent, it sounds like it is a sequence of three different MDC1200-like transmissions. They are, however, slightly longer than the regular MDC transmissions. Based on the information that Batlabs provides on this (MDC1200 Signalling), it looks like call alert is definitely part of this protocol.

I'll continue to mess around with it. Thanks for the information.
 

qball

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MDC1200 signallin

Sounds like that is MDC1200 signalling. MDC1200 is a pretty old format....at least 25 years old.

The benefit of MDC "call alerting" is that the receiving radio will report that it received the alert if it programmed to do so. That report lets the dispatcher know that the EMS unit is receiving it's call.
 

n7lxi

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Yep. Sounds like MDC or FleetSync. It can be used to alert the portables, turn on the station lights, open the PA system in the bunk room... Our QCII paging does all of that, too.


Sent from my iPhone using Tapatalk. Sorry for any spelling errors.
 

jawnah

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After some research, I think this is MDC1200 signaling. I am still trying to verify.

Sent from my phone using Tapatalk.
 

jawnah

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I actually put this on my feed server and found that they are using this to recognize units. The calls yield nothing. That program specifically days it only does single packet transmissions. I wonder if the call alerts contain more than one packet.

Sent from my phone using Tapatalk.
 

jawnah

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After some research again, I believe this is the double-packet MDC-1200 signaling. I found some references to this in demo videos I found on YouTube and, when I listened to the signaling, it sounded right. So I decided to take a look at some old data and I found this link: Batboard • View topic - MDC decoding - info and info request. Here, they explain that CALL ALERT is a double-packet MDC function (something that WinMDCd cannot currently decode).

From what I can see, newer MDC-1200 signaling can be done in single-packet form. I do not believe this is in use on my frequency. I'm going to see if I can experiment more with this and possibly modify WinMDCd because I seem to have a working example.

Thanks for everyone's help!
 

jawnah

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After some research again, I believe this is the double-packet MDC-1200 signaling. I found some references to this in demo videos I found on YouTube and, when I listened to the signaling, it sounded right. So I decided to take a look at some old data and I found this link: Batboard • View topic - MDC decoding - info and info request. Here, they explain that CALL ALERT is a double-packet MDC function (something that WinMDCd cannot currently decode).

From what I can see, newer MDC-1200 signaling can be done in single-packet form. I do not believe this is in use on my frequency. I'm going to see if I can experiment more with this and possibly modify WinMDCd because I seem to have a working example.

Thanks for everyone's help!
 

WayneH

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OP, I've merged this thread with your GenScan thread. Before cross-posting you need to give your thread ample time to get feedback. Two days is not ample.
 

SCPD

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Oops, this is the NORTH Carolina forum. I think you moved it to the wrong place.
 
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