[Lowfer] Strange QRM here on SAQ frequency

Wed Jul 2 23:50:10 EDT 2014

Good morning Graham:

Thanks for the links to your grabber.  I didn't copy anything on 
Sunday morning even though the QRM wasn't present at that 
time.  Seems that lately I haven't had much luck with SAQ but in past 
years I often had good copy.  Perhaps the overall noise level has 
increased at this QTH? I don't keep records of absolute noise levels 
so probably wouldn't have noticed a gradual increase.  The noise 
about which I posted is a relative newcomer and one of the spectral 
lines just happens to be right on 17.2 Khz.  Yes, I can notch out 
those lines easily, but the notch width is wide enough to take out a 
big chunk of SAQ itself if it happens to be on its nominal 
frequency!  That same noise signature was present here during the 
winter SAQ transmission.  I'd say it is present about 90 percent of 
the time now and always on exactly the same frequency: looks like 
powerline modulation of a crystal-controlled carrier.  Wondering if 
it is some kind of signaling used by Hydro One Networks?  It is 
strong enough to DF with a small loop so might drive around the 
countryside to see if I can find the source, although if it is 
radiating from the power line that will be difficult.

Cheers,
Bill VE2IQ

At 07:30 PM 7/2/2014, you wrote:
>Good morning Bill,
>
>You are about 2-1/2 times as far NW of Ottawa as I am SE in Embrun. 
>I monitor VLF an a fairly regular basis only disconnecting when 
>thunderstorms are forecast or actually happening. I have a grabber 
>which puts grabs on dropbox and are updated every 5 minutes:
>
>https://www.dropbox.com/sh/ahvgr4sekcgg99s/zZCqDbxJ02#/
>
>This time of year the level of RFI / EMI is greater than in Spring 
>or Fall with Winter being somewhere inbetween. Most of the RFI / EMI 
>that I have been unable to eliminate is due to running air 
>conditioners, hot water tanks, furnaces, lighting dimmer switches 
>and the occasional odd noisy switching power supply.
>
>On my grabs you can see when these appliances are operating and 
>these are not always the ones located in my house but also nearby 
>neighbours. Their "fingerprint" is the increased noise (the image 
>becomes more green and yellow) on the lower end of the monitored 
>spectrum and the noisier the higher in frequency in extends. The 
>"bluer" the image the lower the noise floor. In Spring and fall when 
>all of the extra appliances are not running the European 
>transmitters are clearly visible as are the Russian transmissions 
>includeing the Beta transmissions on 25 KHz.
>
>I have never been able to fully identify each and every "odd" bit of 
>RFI / EMI that I encounter, some are so fleeting and are long gone 
>by the time I try track them down.
>
>I see from time to time noise as you describe and what is shown in 
>your image. The only recent event that I have noted was yesterday 
>2014-07-01 between about 2214 to 2221 UTC but was centered lower in frequency:
>
>https://www.dropbox.com/sh/ahvgr4sekcgg99s/zZCqDbxJ02#lh:null-ve3gtcVLFgrab20140701_222000.jpg
>
>Did you hear anyting of the SAQ transmission Sunday morning?  I 
>heard only what I describe as "tantalizing whispers", just a wee bit 
>above the noise but never very strong nor long enough duration to 
>get much of any copy.
>
>cheers, Graham ve3gtc FN25ig in Embrun, Ontario
>
>
>On 01/07/14 20:40, Bill de Carle wrote:
>>Hi Everyone:
>>
>>Anyone on this reflector know what could cause some very strong QRM 
>>I see right on top of SAQ's 17.2 Khz frequency?  It consists of a 
>>group of spectral lines spaced 120-Hz apart, centered near 17.2 Khz 
>>but occupying only about 1 KHz bandwidth.  This QRM is present most 
>>of the time at my QTH but oddly enough, it wasn't there on Sunday 
>>morning when I got up around 4:30 am Eastern time.  Obviously it's 
>>powerline-related, but as far as I know (famous last words!) it 
>>doesn't seem to be coming from anything in my home.  I can even 
>>disconnect the mains & run on batteries: the signal does not 
>>change, so it is clearly radiated, not conducted through the power 
>>line.  The amplitudes of the individual spectral lines vary slowly 
>>(cycling over perhaps 20 seconds), seemingly at random.  I live in 
>>a rural neighborhood and there are some electric fences 
>>around.  What bugs me is why at 17.2 Khz?  Have you seen this 
>>signature before?  Here's a screenshot showing what it looks like:
>>
>>http://www.magma.ca/~ve2iq/saq_qrm.gif
>>
>>Any ideas would be much appreciated.
>>73,
>>Bill VE2IQ
>>
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