What is that sound?

[roots]

Hi All,

need some help on getting more info on that sound. It's on the same frequency has voice but you can ear it many times. It seems to be data related or something but not sure.

http://www.filefactory.com/file/agada40/n/sound_wav

what is the procedure to analyse it?

p.s I do have a 4 level slicer if required.

thx all,

Marc

 

[bpsmicro]

It's the radio "squawking" ID information at the end of each transmission. Exactly what's in the data will depend on the service, radio, etc.In your sample, it sounds like somebody is just keying a mic without speaking. I'm not aware of any way to extract the data, and even if you did it'd probably be gibberish.

 

[LordJ]

I agree, sounds like a dead key....what freq is it on?

 

[DaveH]

Those are MDC-1200 bursts, possibly result of mic keying but could also be
sending status messages. You don't need a slicer, it is audio FSK and some
free software exists to decode (can't tell you exactly which).

BTW is on one of the EMS frequencies 153.890 etc. ?

Dave

 

[roots]

Hi Dave,

yes it's on a EMS frequencies.

not sure if it's all mic keying because you can here that randomly...

I will check for some info.

thx,

 

[roots]

They are also using Xplore Tablet PC now so not sure if these PC transmit by the same frequencies or on the 1X technologies!

 

[DaveH]

yes it's on a EMS frequencies.

not sure if it's all mic keying because you can here that randomly...

I don't hear much voice dispatching on this channel, maybe it's on
other frequencies or done by other means (CAD?), or maybe just
a quiet period. I did hear a hospital patch, preceeded by two-tone alert.

Toronto EMS used to have status reporting on its repeaters using
Motorola MODAT. Kind of fascinating sound, having these tone bursts
sprinkled through regular voice activity.

The bursts other that those at the end of transmissions seem random.
Sometimes they seem to occur in pairs, one "chasing" the other, perhaps
a response or ack? One burst lasted about one second, so I'm not sure
it's pure MDC1200; could it support long (batched?) continuous messages?

Dave