OSP mobile repeaters?

[GregOH]

I've been wondering about the OSP mobile repeaters myself. I'm sitting here at home monitoring 465.525 and getting alot of dispatch to car and car to car since it's pretty much the first day of winter driving this year with running license plates and calls at accident scenes.
I'm a mile or a bit more off the highway and if I'm correct, I'm not far from the tower either so with that, I'm wondering where I'm getting the signal from, because I'm using an analog handheld with the stock rubber antenna. I'm also thinking if I were mobile with the scanner, I'd hear little to nothing from this frequency?

 

[n8jsw]

From what I understand OSP went back to using there old uhf frequencies for the bee in the cars and also I have heard it off the tower also

 

[wa8pyr]

From what I understand OSP went back to using there old uhf frequencies for the bee in the cars and also I have heard it off the tower also

That's correct; the old 700 MHz mobile repeaters were originally used with the old MARCS (all 800 MHz) and did not play well with MARCS-IP (mostly 700 MHz); the mobile repeaters and main vehicle radios sometimes caused interference to each other.

So, OSP dumped all of their XTS5000 portable radios, bought all new APX7000 UHF/700-800 dual band portables and went back to their old UHF mobile repeater frequencies.

As far as I know it's all mobile installations, although it's certainly possible that they could have low-profile fixed base units at the patrol posts (that would kind of make sense, actually). OSP does have a post at New Philadelphia so that might be what Greg is hearing. I'm not too far from the Circleville post; may have to search those and see if Post 65 is doing something similar.

Greg: you are correct, you won't hear much on those while mobile unless you're close to a trooper who has his repeater turned on. Pretty handy way to tell if you're close to a trooper, though.

 

[scannerboy02]

I'm glad someone brought up the OSP VRS.

I spend a good amount of my day at a hospital and see a number of OSP vehicles parked in the ED lot and I have been scanning the UHF (and old 700 MHz) frequencies and have never heard a VRS active. Is it possible the troopers in the area have the portables on MARCS directly and are not using the VRS? The hospital has very good coverage from the Hamilton County site, they have a tower right up the street.

 

[GregOH]

The only thing I dislike about scanning OSP on this conventional frequency is, I'll hear beeps leading up to a transmission. After that, I'll hear the car and dispatch conversation with no beeps and will only get them again after the frequency is idle for a period of time.
As for going mobile, I have the scanner set on a limit search with it scanning the range of 465.375 to 465.550 to see what that yields. Didn't get anything with it this morning, but that was at 4-5 am.

 

[W8UU]

The only thing I dislike about scanning OSP on this conventional frequency is, I'll hear beeps leading up to a transmission. After that, I'll hear the car and dispatch conversation with no beeps and will only get them again after the frequency is idle for a period of time.
As for going mobile, I have the scanner set on a limit search with it scanning the range of 465.375 to 465.550 to see what that yields. Didn't get anything with it this morning, but that was at 4-5 am.

The beeps are most likely the "Singletone" automatic sensing tone that mobile repeaters send out to see if there's another repeater on the air. The more sophisticated VRS units will shut down if another repeater on their system is in the immediate area. This was the difference between the Motorola PAC-RT systems and the more basic PAC-PL.

An explanation from onfreq.com:

The difference between the PAC-PL and PAC-RT is the PAC-RT has a priority resolution scheme to prevent multiple mobile transmitters from interfering with each other. If two or more PAC equipped vehicles that use the same handheld frequency and/or same mobile frequency were to be keyed up together by a handheld radio, the result would be that the radios on a common frequency would jam each other. This would result in a total mess and will prevent any communication. The same applies to the PAC unit transmitting to the handheld radios. Multiple vehicle based PAC units transmitting right next to each other on the same handheld radio frequency will jam each other and result in another mess. The PAC-RT priority resolution scheme will automatically shut down all but one PAC-RT unit when a bunch of them are parked near each other. An audible tone called a Singletone is used by the PAC-RT priority resolution scheme. The PAC-RT operating frequencies, PL tone and Singletone frequency must be setup correctly to work with each other.

The PAC-PL does not have this priority resolution scheme, so a PAC-PL system installed in multiple vehicles would need to have each PAC-PL unit and its handheld radio on a totally different simplex frequency to prevent interference between handheld radios. If the other PAC-PL units can not all hear the mobile radio frequency and repeat it to their handhelds, or if the handheld radios de-sense each others receivers, you would still have multiple mobile radios keying up on the same frequency (i.e. with all the handheld radios on different frequencies you can not hear someone else using their PAC-PL unless your setup is repeating the mobile frequency back to your handheld on its unique frequency). The need for multiple, unique, channel frequencies is why PAC-PL is not practical when you have multiple PAC-PL units using a common radio communications system in the field together.

Just a guess but I believe this is what you're hearing.

 

[wa8pyr]

I'm glad someone brought up the OSP VRS.

I spend a good amount of my day at a hospital and see a number of OSP vehicles parked in the ED lot and I have been scanning the UHF (and old 700 MHz) frequencies and have never heard a VRS active. Is it possible the troopers in the area have the portables on MARCS directly and are not using the VRS? The hospital has very good coverage from the Hamilton County site, they have a tower right up the street.

They have both. OSP portables are dual-band which include both UHF (for the repeater) and 700-800 MHz (for MARCS). If MARCS coverage at the hospital is sufficient, there's no need for the troopers to use vehicle repeaters and they can put their portable radio directly on the post talkgroup. If the trooper is on a traffic stop on Route 37 in East BFE, they'll almost certainly use the repeater.

The beeps are most likely the "Singletone" automatic sensing tone that mobile repeaters send out to see if there's another repeater on the air. The more sophisticated VRS units will shut down if another repeater on their system is in the immediate area. This was the difference between the Motorola PAC-RT systems and the more basic PAC-PL.
<snip>
Just a guess but I believe this is what you're hearing.

Rick is correct; OSP uses Pyramid vehicle repeaters which send out the tones just as described.

The description of the difference between the old Motorola PAC-RT and PAC-PL systems is also an interesting historical tidbit. Many volunteer fire departments experienced the very problems described; since PAC-PL was less expensive than PAC-RT that's what most volunteer departments bought; many used 153.830 MHz as their portable frequency, and when everybody was using the same portable frequencies (even with different PL tones on the portable frequency), partial chaos usually resulted.

Another historical tidbit... back in the low-band days, OSP PAC-RT units were wired to an interesting circuit (which I'm told was devised in-house by OSP radio techs) that was connected to the dome light in the vehicle; when the trooper opened the door and got out of the car, it activated the PAC-RT which responded with a "beep" on the portable frequency to let the trooper know the repeater was active. When the trooper opened the door and got back in the car, the clever little circuit deactivated the repeater.

 

[GregOH]

I don't think the repeaters are set to activate when they leave the car only, because I have heard talk of mile marker location and getting off at New Phila exit. I'm also thinking when I'm hearing a car and dispatch communicating both transmissions are coming from the repeater rather than a tower because I only hear dispatch when they respond to the active mre.

 

[mjschwartz2003]

so they are not useing marcs ip? i am in the cleveland area...i here very little radio traffic from them...

 

[wa8pyr]

I don't think the repeaters are set to activate when they leave the car only, because I have heard talk of mile marker location and getting off at New Phila exit. I'm also thinking when I'm hearing a car and dispatch communicating both transmissions are coming from the repeater rather than a tower because I only hear dispatch when they respond to the active mre.

They can be set up many ways; in my county they were set up so the deputy could activate it using an option button on the vehicle radio. OSP probably leaves them on all the time; doesn't really hurt anything.

so they are not useing marcs ip? i am in the cleveland area...i here very little radio traffic from them...

Yes, OSP are using MARCS. Cuyahoga County is one of the areas where OSP doesn't do as much enforcement since most of the freeways are within municipal boundaries; when OSP writes a ticket, the fines don't go to the municipality, so the municipalities pitched a fit.

 

[mjschwartz2003]

They can be set up many ways; in my county they were set up so the deputy could activate it using an option button on the vehicle radio. OSP probably leaves them on all the time; doesn't really hurt anything.



Yes, OSP are using MARCS. Cuyahoga County is one of the areas where OSP doesn't do as much enforcement since most of the freeways are within municipal boundaries; when OSP writes a ticket, the fines don't go to the municipality, so the municipalities pitched a fit.

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