142.770 in Ottawa

[VA3XDJ]

I recently programmed this frequency:

142.77000 RM CSQ OPCCommon Police Common - Mutual Aid all police FM Interop

I'm not sure if I'm receiving a carrier from nearby electronics causing RF or if there is an actual carrier transmitting 24/7?

Can anyone in my area confirm?

 

[IdleMonitor]

I'm an hour west of Ottawa and I get that as well from time to time, depending on location.

I recently programmed this frequency:

142.77000 RM CSQ OPCCommon Police Common - Mutual Aid all police FM Interop

I'm not sure if I'm receiving a carrier from nearby electronics causing RF or if there is an actual carrier transmitting 24/7?

Can anyone in my area confirm?

 

[VA3XDJ]

Has anyone actually heard any activity on this frequency?

If so, is there a tone present?

I programmed the other simplex frequencies and either I hear nothing or I hear digital bursts which I'm unable to confirm if they are actual traffic or intermod due to my location.

 

[Jammin_Jay]

Check the input frequency
Sometimes, if the ss is strong enough, it will trip the repeater for output on OPC common channel.
I have come across this before.

138.750 check +/- about .015

One time i heard 2 people talking, on 138.755 , and simulataneously i turned on the other scanner to
142.770, and sure enough i heard it, little off frequency, but just enough to hit the repeater, and NO it was not police, it was just 2 guys talking about buildings, and girls, and other things.

this was 3 years ago.

I don't think there is a PL tone, or you wouldn't hear the relay on the repeater


Usually, there is no radio traffic Between Ottawa Traffic units OPP ,and OPS ottawa police service, their dispatcher, contacts the Smithsfalls comm center. Very rare you will hear some directly related to Ottawa, but the surrounding counties definitely hear activity from time to time. Especially Sunday evening Radio comm checks, between units or the odd police car chase through eastern ontario towns.

What are you using for a scanner?

 

[VA3XDJ]

Good to know!

I'm using a Yaesu FT-8800 fed directly to a Jetstream JTB3 about 25 feet off the ground with 50' of LMR400

Thanks for the info!

Much appreciated!

 

[frankh]

This doesn't make a lot of sense to me (AM tripping an FM repeater) but for several years occasionally you would hear the OPC repeater keying coinciding with mil air activity

 

[DaveH]

I'm receiving a fairly-strong constant carrier on 142.770, downtown Ottawa. It's been
like this for months if not years, and not local interference. I also checked the input and
heard nothing (which could also mean something's there but I can't hear it) but I doubt
it's on the input. No explanation why it's like that.

Dave

 

[exkalibur]

This doesn't make a lot of sense to me (AM tripping an FM repeater) but for several years occasionally you would hear the OPC repeater keying coinciding with mil air activity

You were likely hearing an image from the air band. If something were to transmit on 121.370 (or somewhere in the area of it), it'd come through 142.770. I used to hear Cleveland Center on 132.400 come through very strong on 153.800 (local FD frequency). I would go 5kHz off and it would go away.

 

[DaveH]

You were likely hearing an image from the air band. If something were to transmit on 121.370 (or somewhere in the area of it), it'd come through 142.770. I used to hear Cleveland Center on 132.400 come through very strong on 153.800 (local FD frequency). I would go 5kHz off and it would go away.

Not necessarily. Several years back I observed a case of a 142MHz repeater being tripped by US air
activity in the 138MHz band; probably ANG. I believe it is listed somewhere but don't recall where, in this
DB or possibly NF2G's. In some cases where the 15kHz and 12.5kHz steps align, the frequencies are
exact, otherwise offset. This was on a PRO-2004, triple-conversion so doesn't suffer the 21.xx image
problem; also I tend to verify on another receiver with different IF's.

With non-conventional repeaters, chance of this happening are unlikely, but with conventional
without CTCSS access (fairly rare these days), this can occur.

Dave

Update: found this is the RRDB under AF SAR: 138.750, which happens to be...the input to 142.770.

Common Military Scanner Frequencies and Radio Frequency Reference

This is not the case I was describing above.

 

[exkalibur]

Well, OPC repeaters need a tone of 107.2 in order to key up, so I doubt a CSQ transmission could set it off in that example. He mentioned it was AM, so...

 

[mikewazowski]

Every one I've ever seen has been CSQ.

 

[DaveH]

Well, OPC repeaters need a tone of 107.2 in order to key up, so I doubt a CSQ transmission could set it off in that example. He mentioned it was AM, so...

So are you saying that an AM carrier on or near the input of a CSQ repeater would not trip it?

Dave

 

[exkalibur]

I just tried to key up a CSQ ham repeater on VHF AM and it did key up, however the audio was totally unintelligible - so it is possible. Just unlikely unless the user was very close. I can't imagine the use of 138.750 is very "legit" near the Ontario border.

 

[Jammin_Jay]

Yes Dave, it is possible. The example I gave about the input frequency was being tripped by 2 operators talking on AM VHF, as exalibur said, it sounds garbled, but it still can trip the 142.770 repeater CSQ if the signal strength is strong enough to break the squelch whether AM or FM (CSQ). If i could only get a audio sample to play for you guys.

If you listen to 138.750 on FM, but the actual audio modulated is AM, you will hear the exact same thing on 142.770 FM.
But i do see your point exkalibur, but what i heard sounded like 2 people talking illegally on the input frequency as AM

As for the carrier being open, with nothing heard, yes i hear that. And it seems to have a contour of 70 km or so from ottawa
Because I can hear it west and east and south of the city, before it starts to flutter and fade.