Topband: Another take on power line noise hunting

[W2PM]

Re a portable oscilloscope to look at noise signatures (the number of "points" on the waveform is a basic but good way and u can usually discern multiple sources too) is to use a audio spectrum analyZer ap on an iPhone. I assume these may be available on a Droid too. I use several and some are free or close to free.  You can actually use the microphone on the fone as the pickup if you can couple to the receiver with a piece of cloth.  These aps are fairly decent too being able to change time base and amplitude. Of course a small laptop with a PC based application is better and you can plug into the line input and get a more reliable reading and record the noise as well. 

73 Pete W2PM

Sent from my iPhone

On Jan 6, 2013, at 6:40 AM, Pete Smith N4ZR <n4zr at contesting.com> wrote:

> Or, since you don't really need a calibrated result, build a simple variable attenuator.  Just about anything works so long as you can vary the sensitivity as you approach the power line.
> 
> 73, Pete N4ZR
> Check out the Reverse Beacon Network at
> http://reversebeacon.net,
> blog at reversebeacon.blogspot.com.
> For spots, please go to your favorite
> ARC V6 or VE7CC DX cluster node.
> 
> On 1/5/2013 1:17 PM, donovanf at starpower.net wrote:
>> Hi Paul,
>> 
>> You would helpful a step attenuator, in 1 dB steps, to be a valuable addition to your tool bag.  There are situations where it helps isolate to an individual pole.  Its much more accurate than an S-meter.
>> 
>> Something like this, or many other alternatives:
>> 
>> http://www.ebay.com/itm/Coaxial-RF-Step-Attenuator-Set-1-dB-steps-to-70-dB-total-DC-to-1-GHz-/200866468929?pt=LH_DefaultDomain_0&hash=item2ec4931441
>> 
>> 73
>> Frank
>> W3LPL
>> 
>> ---- Original message ----
>>> Date: Sat, 05 Jan 2013 11:44:08 -0500
>>> From: N1BUG <paul at n1bug.com>
>>> Subject: Topband: Another take on power line noise hunting
>>> To: Topband <topband at contesting.com>
>>> 
>>> I've been following this discussion with interest. I spent the
>>> summer tracking down more than 20 sources of power line noise. As an
>>> offshoot of that I've made it my mission to help clean up RFI in my
>>> little corner of the world. I've been slowly drifting away from
>>> DXing and this has turned out to be my new area of interest.
>>> 
>>> Since this topic is perhaps of interest to topbanders, and since my
>>> experiences seem to vary somewhat from the typical reported here so
>>> far, I thought I would take a moment to share some observations. I
>>> should probably note I was dealing with a mix of 13.2 kV
>>> distribution lines and 46 kV transmission lines. My hunt was made
>>> more challenging by the fact I had multiple sources in a relatively
>>> small area and could often hear more than one at a time even with
>>> directional antennas and attenuation.
>>> 
>>> My tools this summer were 135 MHz AM receiver with 3 element yagi
>>> and step attenuator; LF/MF/HF/VHF/UHF AM receiver with DF loops for
>>> low bands and 7 element yagi for 445 MHz; ultrasonic receiver with dish.
>>> 
>>> Low frequencies, eg. AM BC or 160 meters were *occasionally* useful
>>> in locating a general source area. Sometimes the area identified
>>> turned out to be an area of *radiation* but the noise was
>>> *generated* elsewhere. Often the relatively close proximity of
>>> multiple sources made low frequency tracking useless.
>>> 
>>> VHF was always useful in finding a source area, 80% of the time
>>> resolving it to a single pole. The sharp, deep null at exactly 90
>>> degrees off axis of the yagi proved very useful for confirming a
>>> source structure. Poor resolution/accuracy of signal strength
>>> metering was perceived as a problem.
>>> 
>>> UHF was very helpful in a few areas where the noise was particularly
>>> strong at VHF and/or signal strength so close over a span of several
>>> poles that VHF could not pick the source pole with high confidence.
>>> So far, experience indicates this is more likely to happen on the
>>> transmission lines. They're a bear. Again, poor or no signal
>>> strength metering (signal below AGC threshold) was perceived as a
>>> problem.
>>> 
>>> The first ultrasonic unit tried was a waste, finding something at
>>> only 10% of RF noisy poles. The second unit was able to hear
>>> something from about 60% of the same 21 poles. The figures are
>>> averages over more than 10 runs with each unit. The two were also
>>> tested on a spark signal range under somewhat controlled conditions.
>>> These things are definitely not created equal!
>>> 
>>> To date I have identified and had the power company fix almost
>>> everything I have worked on. The remaining open case involves a
>>> short section of a 46 kV transmission line which is extremely
>>> perplexing due to the specific nature of the issue (details on
>>> request). Just when I starting thinking I was getting good at this,
>>> I came up against this one.
>>> 
>>> If I were doing this strictly for myself these tools would be more
>>> than adequate. Since I'm not and I only have so many hours in a day
>>> I have several upgrades on my wish list:
>>> 
>>> HF/VHF/UHF AM receiver with wider bandwidth better signal strength
>>> metering
>>> 
>>> Log periodic dipole array covering ~100 to ~900 MHz for frequency
>>> agility while maintaining some directional properties
>>> 
>>> Portable oscilloscope for observing noise signatures in the field
>>> (I'm hoping it helps sort out overlapping source radiations)
>>> 
>>> Yet another upgrade of the ultrasonic unit.
>>> 
>>> Comments are welcome, even if it's to tell me I'm clueless!  :)
>>> 
>>> 73
>>> -- 
>>> Paul Kelley, N1BUG
>>> RFI Committee chair,
>>> Piscataquis Amateur Radio Club
>>> http://www.k1pq.org
>>> _______________________________________________
>>> Stew Perry Topband Distance Challenge coming on December 29th.
>> _______________________________________________
>> Stew Perry Topband Distance Challenge coming on December 29th.
>> 
> 
> _______________________________________________
> Stew Perry Topband Distance Challenge coming on December 29th.