Repeating Transmissions?

[ScubaJungle]

I've noticed that twice today, when scanning I heard a dispatch call, then the scanner started searching, and that same call came over again - exactly the same, couldn't have been a similar/"redo", the same transmission repeated.
What can cause this, and is it potentially an issue/something wrong with my scanner?
The only idea I have is that I have two favorites lists scanning the same systems, but one has more delay? The only issue with this is that I have never messed with delay times.

 

[mmckenna]

What system/frequencies did you hear this on?

There's some cheap "store and forward" type repeaters. You won't hear those very often but if you do they'll be on amateur or GMRS type radio services.

If it was something public safety related, could be a linked repeater with a -r-e-a-l-l-y- long delay.

 

[n1chu]

What scanner did you hear this on? Does it have the ability to record, such as the SDS100 or SDS200? I have both of these radios but have never bothered with the record/playback feature so what I’m suggesting is that maybe you have the record feature turned on?

 

[ka3aaa]

it could also be testing on a new system under construction.

 

[nd5y]

There's some cheap "store and forward" type repeaters. You won't hear those very often but if you do they'll be on amateur or GMRS type radio services.

I have heard those (I think two in the DFW area a long time ago) on rural VFD paging frequencies.

 

[n1chu]

How so would it be used for testing? Who’s going to bother to create a recording just for what usually is only a one or two time need? Systems using a semi-duplex (two frequency) repeater repeat every time the repeater is activated by a transmission on the input frequency with the proper coding. But I don’t believe that is what the question here is about. I have never heard a transmission repeated over the air that was a rebroadcast of an earlier transmission... that would be a recording. Last I knew, comms were routinely recorded for review, stored for a later review... but never patched back into a system with a time delay circuit.

That being said, I recall audio from automated systems where the dispatches are created using computers. A robotic-like Computer generated voice would alert the dept. In a case such as this, that same computer generated dispatch may get repeated to accommodate the usual routine request for a repeat because somebody didn’t catch all of the dispatch... instead of requesting a repeat they just wait until the dispatch got repeated automatically.

 

[KevinC]

I have heard those (I think two in the DFW area a long time ago) on rural VFD paging frequencies.

Justin VFD in Denton County has one that is still active.

 

[drdispatch]

....That being said, I recall audio from automated systems where the dispatches are created using computers. A robotic-like Computer generated voice would alert the dept. In a case such as this, that same computer generated dispatch may get repeated to accommodate the usual routine request for a repeat because somebody didn’t catch all of the dispatch... instead of requesting a repeat they just wait until the dispatch got repeated automatically.

There is a county in northern Indiana (St. Joseph, maybe?) that dispatches using the computer voice over the air. The transmission is then repeated after a minute or so. Since it's the CAD "reading" the call info, it is exactly the same each time.

I would also support the scanner record/playback feature theory, presuming that the OP has a scanner with that feature.

 

[ScubaJungle]

So the system is a Public safety system, specifically EDACS. The repeating transmission came from the same system, and same TG, the only thing Im unsure of is if it was on the same favorites system, or if it was a different one (one is that whole system, and one is just a few talkgroups on that same system.)

I have the BCD436HP which can record (I believe) but I have not played with that feature yet - it isnt a common ocurrence so I'm not sure how long it would be before I finally am on the right time to get it.

I dont believe it was testing a new system, because the new system is P25, and this was on EDACS.

I'm not sure hwat you mean by computer-generated, but this was a persons voice, which is how I could tell that it was an exact repeat so easily.

I may have forgot to mention - the dispatch repeated, but so did the fire truck who responded. Both the dispatch and reply repeated.

 

[n1chu]

I’d check the scanners repeat option and assure it’s off... let’s us know what you find.

 

[doctordialtone]

I’d check the scanners repeat option

Where is that?

 

[n1chu]

Where is that?

That should read record option. It’s in the manual.

 

[jeatock]

Sounds like a store-and-forward simplex repeater. They're not too common, but useful for remote areas with poor central site coverage and little traffic. Midians makes an add-on board for mobile radios that makes this an inexpensive alternative to a full-blown duplex repeater. A power supply, mobile radio and a magnetic antenna on a metal roof is all it takes.

Another possible variation: My county uses a single, common, dedicated dispatch notification channel for all fire and EMS alerting. 12 years ago I set up multiple 'remote' repeaters for tones and dispatch voice (all listening to the same input frequency but with different CTCSS for each) for bulletproof coverage across the county, The main site in the middle (with 'pretty good' coverage of the county) records all pages, waits 18 seconds, and replays them. This gives us an automatic repeat, alerts responders who are not 'at home' plus creates an automatic backup in case the remote repeater fails.

Since the output channel is one-way (no mobile talkback) there is no danger of an automatic repeat walking on any mobile traffic.

Could a new system like this be what you are hearing?