[Lowfer] Strange QRM here on SAQ frequency

Sun Jul 6 21:32:09 EDT 2014

Bill,

Got to thinking some more on your strange RFI / EMI.

I don't think I have ever heard the type of emi/rfi that an electric 
fence or invisible dog fence might generate so I have no point of 
reference with those.

However, the types of emi/rfi that I do see are aside from furnaces and 
airconditioners and is on and off during the day is that from dimmer 
switches, outdoor sensored lights, hair dryers, and networks but they 
don't seem to bother me too much  and except for networks are short 
lived and are on and off fairly quickly. Network emi/rfi tends to be 
more HF.

If what you have is on nearly all the time and is it possible that 
someone local has started to use a home network using broadband over 
power line?  I have never heard or am familiar with the spectrum of this 
this type of emi/rfi maker.

In Embrun we have both smart power meters and remote reading water and 
gas meters. I think the water and gas meters use some sort of VHF 
frequency but have been unable to verify; I don't know about the "smart 
power meter" however.  I didn't notice any new emi/rfi suddenly appear 
when any of those devices were installed

do let us know if you ever figure out the source of your strange QRM.

cheers, Graham ve3gtc

On 2014-07-03 03:50, Bill de Carle wrote:
> 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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