Is Signaling Used in Your Area?

[RandyB]

I guess I have to admit that I've always liked signaling (PTT ID). Yeah, some find it annoying. I don't know why I find it so fascinating.

I grew up listening to Nashville Police on VHF. They used the long form of GE star signaling which, even to me, could get very annoying at times. In all my travels I have yet to hear any other public safety agency who uses the long form of GE star signaling. The shorter form seems to be pretty common still. I think few would argue that MDC1200 is the most popular now.

I'm curious to hear from others as to what signaling (if any) is in use in your area. Is MODAT in use by any departments? Los Angeles and Denver Police Departments are the only users of MODAT that I know of. Of course, both agencies have moved on to newer equipment and no long use MODAT signaling. What about MDC600? In Tennessee, both Gatlinburg Police and Cookeville Police use MDC600.

I think the most interesting agency I've ever listened to with regards to signaling is Gainesville Florida before they moved to trunking a few years ago. I recall several forms of signaling in use buy Gainesville PD from MDC1200 and MDC600 to some odd form of MODAT.

If you’re not familiar with signaling… there are a few .wav samples on the following site: http://www.kb9ukd.com/digital/

 

[kgasso]

Only one police agency in my area utilizes PTT ID for it's units - they use MDC1200 bursts at the beginning of transmission. The rest are simply voice and nothing more.

By the way, thanks for the awesome link.

 

[BoxAlarm187]

Many of our local agencies use MDC1200 coding, and Virginia State Police uses GE-Star.

 

[fire4456]

st. joseph co. indiana uses it exclusively for pd and fd elkhart county some departments use it mainly cleveland and osolo use it to id radios so they know who is talking. St. joe co fire dispatch also has the ability to shut off the radiso in the case of lost or stolen as indiacated byt the users id.

 

[Radiorick]

After reading this post I have a few questions ...

Are these push to talk id's just random dtmf tones?
Wouldn't the longer signals delay an urgent msg from being sent?
About how long are the tones?


alright cheers...

 

[BoxAlarm187]

They're more like very short data-bursts, that last less than a second. I've never experienced (either as a user or a listener) urgent traffic being delayed due to the PTT ID being transmitted.

The link provided in RandyB's original post provides examples of these ID's. You have to look for them, though! They're about halfway down the list.

 

[cipher66]

After listening to the audio samples I believe that Baltimore City FD used to use MODAT signalling when they were on the old VHF system (154.31). Interesting thread on this subject. Do current P25 or even analog TRS's use these anymore or is the capability built-in to the system already?

 

[fire4456]

this is in response to the last reply kinekep. The trs I used to be on in marion county which was wayne twp edacs used to have it built in with no audible tone. I don't know if this is a different frequency or if it was sent on the control channel or how it was done. I do know that each radio had it's id and it told you who was talking to you and on what group ie 11-18. So this is the best explination i can offer

 

[cipher66]

Thanks Fire4456,

Yes, I thought that TRS systems were able to radio ID over the air, I suppose it's built in to the digital subsystem/computer that assigns radios to the systems, etc... Cheers!