[Lowfer] Strange QRM here on SAQ frequency

[Graham]

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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