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Can anyone recognize this signal?

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jwt873

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#1
We have a repeater 444.500+ that's getting hit by QRM on the input 449.500 Mhz

It consists of a pulsing signal that beeps steadily about once every second. It doesn't run all the time. It can go for an hour or so, then it stops for an hour or so.

We've done some triangulation with our beams, but nobody lives near where the source seems to be coming from. Here's a sample. (It's not that strong at my place, but really interferes with our repeater which is a lot higher than me).

https://dl.dropboxusercontent.com/u/10425557/440band-qrm.mp3

Has anyone heard a signal like this anywhere on the VHF or UHF bands? Knowing what it is might help track down the source..

Thanks in advance
 
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#2
I prob wont be much help but kinda sounds like a beacon. Not sure if thats static between the beeps or other digital signal. Have you seen what it looks like on a Scope/Waterfall. Also where you think its coming from may help in case someone in that area can help.

But a beacon on UHF on that freq? idk..
 

nd5y

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#3
Did you make the recording with the squlech open the whole time?
It sounds like a GPS RTK station. They send a data burst once a second. They are used mainly by surveyors and farming and construction. It could be a nearby one putting out a spur on 449.5 or they could actually be using 449.5. In the US there are several UHF frequencies they are commonly licensed on. I don't know how they are licensed in Canada.
 

jwt873

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#8
Thanks for the suggestions. Here is a bit more detail:

The FM signal is weak at my place and not full quieting so in the recording the signal is coming through a lot of hiss.

I just found out that it doesn't transmit all the time. Yesterday, it went on for about 2 hours early in the morning and then came back for a little over an hour and a half later in the afternoon. It hasn't come on at all today.

The repeater owner went out tracking the signal and has narrowed it down to the north side of the City of Winnipeg. So it's located in a built up part of a city with a population of 700K. This puts it about 30 miles from my place.. Which is why the recording I made is so weak.

Unfortunately because it's intermittent and it stops for extended periods, It's difficult to narrow down. But now that we have a general location, we should be able to find it eventually. I'll post what it was when we find out.
 
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#10
5.3.4 430–450 MHz
Domestic Allocations

Radiolocation - Amateur
Utilization Policy

The band 430–450 MHz is available for the radiolocation service on a primary basis. Should the need arise in Canada, the Department of Industry may accommodate wind-shear radar/wind-profiler operation in the upper portion of the band 430–450 MHz as a radiolocation type of service.

The amateur-satellite service is permitted in the band portion 435–438 MHz on a secondary, non-protection, non-interference basis. In addition, and on the same secondary basis, the amateur and space operation services and the space research service are permitted in the band portions 440–450 MHz and 449.75- 450.25 MHz, respectively.

I believe amateur band is secondary for that freq range, out here in the West we have had business LMR simplex in use at 447 Mhz , most notably before the Port Mann bridge was replaced there was a crew working there on simplex, and a number of ski seasons ago Grouse Mountain had a bunch of UHF simlex mainly in 464 region than 3 freq I came across in use @ 446 & 447, only lasted two ski seasons than done.
I have heard this tone before, If I recall it was for concrete truck operator operating a swing boom wireless all over UHF band.
Like someone said Fox hunt time.
 

jwt873

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#11
The band 430–450 MHz is available for the radiolocation service on a primary basis. Should the need arise in Canada, the Department of Industry may accommodate wind-shear radar/wind-profiler operation in the upper portion of the band 430–450 MHz as a radiolocation type of service.
Yes, we are secondary to radiolocation... I did search the Industry Canada frequency database to see if there was anything licensed at the top end of the band. There are a lot of commercial stations running at 440.xxx Mhz, (Here's one: TAFL Search Results: ). But there's nothing nothing up at 449.500..

I even checked for commercial stations just above 450, in case one might be a little off frequency,

The repeater has been running for years.. The QRM just started in the last month. There is construction where the signal is strongest. Will have to check out cranes....

Thanks for the reply.
 
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#13
Don't forget it could be an image / harmonic
Here in the US we find those GPS beacons in the 460-465 Band

Even tracked a few to the 465-470 on some inputs to Repeaters

Yes, we are secondary to radiolocation... I did search the Industry Canada frequency database to see if there was anything licensed at the top end of the band. There are a lot of commercial stations running at 440.xxx Mhz, (Here's one: TAFL Search Results: ). But there's nothing nothing up at 449.500..

I even checked for commercial stations just above 450, in case one might be a little off frequency,

The repeater has been running for years.. The QRM just started in the last month. There is construction where the signal is strongest. Will have to check out cranes....

Thanks for the reply.
 

nd5y

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#14
Here in the US many GPS RTK manufacturers/dealers license the users for itinerant or temporary operation on several common frequencies:
461.025
461.075
461.100
462.125
462.375
462.400
464.500
464.550
464.600
464.625
464.650
464.700
464.725
464.750
469.500
469.550
I don't know if the same frequencies are also used in Canada.
You might check if you can hear the same 449 MHz signal on any of them at the same time.
 
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#17
how about

How about a medical device?Or weather station sending unit?These are in the 440 band..........
 
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jwt873

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#18
Here in the US many GPS RTK manufacturers/dealers license the users for itinerant or temporary operation on several common frequencies:
(snip)
I don't know if the same frequencies are also used in Canada.
You might check if you can hear the same 449 MHz signal on any of them at the same time.
After several months, we finally tracked it down. (It was hard to find because the interference sometimes went away for weeks on end).

It -WAS- a GPS/RTK surveying receiver. (See picture below). The surveying crew had it transmitting on 449.500. We spoke with the company and they agreed not to use our repeater input.

We did a bit more digging and these units are regulated by the Canadian version of FCC Part 15 (Must accept interference but not cause interference), so if the company doesn't cooperate, we have legal means to go after them.

A successful conclusion :)
 

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