Identify and tracking Noise Source

experimenter

Currently in the process of tracking down a noise source which is giving me S5 noise from West to North.. no real trace in any other direction.

I have a 5 element yagi on a 20ft boom at 30ft...

At 330 degrees it peaks to S5 which is giving me grief when beaming to North America and West to the Caribbean....

Frequency of interest is 50Mhz... it also appears on 70Mhz but not as strong..

I know there's one or two experiments on this website...one of which has the same issue, so this may help others.

Switched on the rig this morning beaming 330 and it's so so quite it was bliss to listen to white noise, but I had to leave for work. I know when I get home this evening it will be there again..

So I need to workout at what time the noise starts and stops, this I will do with the aid of a webcam....in order to establish a time pattern..

My question would be at signal S5, any idea as to the distance the noise source would be from me...

Also because I can narrow the noise to 330, can I be sure it is coming from that direction?

I am living out the country with very few neighbours on an elevated site.

At least I know that the source seems to be able to switched on/off..

My plan is AM receiver and a VHF yagi and see if I can track it down, but I have no idea as to the distance..

Do I just walk in the direction of 330 down the fields until I can trace it???

BTW, I didn't have this problem last year and I did notice a drop in signal strenght of the noise when I lower the beam to 15 feet.

I know the IRTS, which I am a memeber of, have a EMC rep, so I may pop him an email.

Thanks in Advance.

**Please try to stick to the subject posted, I do notice that comments, tend to stray from the original post**

gerryk

Triangulate...

Use your home as the start point... plot it on a map, and then draw a line in the direction that the signal is strongest. In other words, if it's 330 degrees from your house, draw a line along 330 degrees (kinda north-north-west).

Then taking your AM receiver and yagi and a GPS unit... drive 20 or 30 miles east or west and do another reading. Plot this point and the line along which the strongest signal is received.

Drive another 20 or 30 miles... maybe heading north this time and repeat. At this point, you should have something like an intersection on your map, where the 3 lines meet, or at least come close. This is the vicinity of your problem.

This is a simplification, since your yagi will have a beamwidth in the region of 50 degrees, and as such the line you draw is not an accurate representation, but it shoud do fine in this instance.

experimenter

I found a good link which will help my issue.

http://ims0.osiemaps.ie/website/publicviewer/main.aspx?id=&utype=&ecom=S1&user

experimenter

Looking at a bearing of 330 it could be the neighbour directly above me!

OSI a big help

watty

IF you know where deepest null is (use 50.05MHz beacon to find the two depest 180 apart null), you can use a portable dipole. The null is sharper than the peak.

experimenter

Sorry you have lost me?

watty

A big yagi for 6m isn't very portable.

A dipole is, but not very directive. Any dipole and most Yagi have a sharper null than width of beam.

Verify this using Hill of Allen Beacon on 50.05MHz (which I can hear mobile in around Limerick).

Then you can go out and get a couple of beaings taking the Null angles for accuracy tio triangulate source.

While a null on a dipole is along the rod, on a yagi the deepest pair of nulls could be anywhere off the main beam lobe.

gerryk

experimenter wrote: »

I found a good link which will help my issue.

http://ims0.osiemaps.ie/website/publicviewer/main.aspx?id=&utype=&ecom=S1&user

You think that's good?? This will really blow your mind in that case...

http://maps.google.com/

experimenter

I have seen google maps before, google earth etc... but this is of no use to me, as I said I am in the country, at least with the OSI maps I get the layout of fields, houses...

gerryk

Fair point... it does have some interesting overlays alright

fatboymsport

i have noise on 6m and 4m here to, with the help of the IRTS EMC guy i have it tracked down to Tree's across the field when wet are touching a 10kva power line and arcing.

what i did was put a 6m 1/4 wave whip on a scanner with am and walked around the field till i got the strongest signal.

he told me to check 2m and 70cms also that if you can hear it on both it is close.

on 6m it could be a mile or more away

i built a 7 el 70cms portable yagi out of bits of coax and a pvc pipe to track it down i havent had the time and thankfully the noise hasnt been to bad the last few days.


didnt get to try the yagi yet.

do a video and stick it on you tube and look at tony's video on there see if it is like that. His has the same type noise as mine only 100 times stronger.

experimenter

Video uploaded if you want to have a listen.

watty

The only noise issue I've had here is cattle fence. Oddly the old FT101ZD noise blanker on 80m removes it entirely and none of the "modern" radios are as good.

experimenter

No Cattle fence problem here and can't tell about HF, as I don't operate on these frequencies.

NB on FT-847 works fine when needed.

the_syco

maps.live.com gets updated more that maps.google.com and thus may be of more use to you. It also often has patches of towns outside the extended Dublin district with fairly good resolution.

/edit
Hasn't gotten to Waterford yet, though.

experimenter

Maps still not as good as OSI. As far as maps go I have loads at this stage.

watty

experimenter wrote: »

No Cattle fence problem here and can't tell about HF, as I don't operate on these frequencies.

NB on FT-847 works fine when needed.

Much more open space on VHF/UHF/SHF

The FT847 a very great radio. I have a good list of 4m mods for it if I ever get one. No wonder the S/H prices are high.

fatboymsport

i looked at the vid and it does sound a bit like what i have here but its hard to tell.

with the scope on the pro it is easier to see the noise across the band.

have you a scanner that covers 50 mhz with AM ??

head across the fields and see what you can find.

are you getting it on 2m ???

experimenter

Yes I have two scanners that have 50MHz AM.

No I don't seem to have it on 144/432, as I don't have a directional antenna, only using X510.


Fine weather to head off out the fields looking for noise :cool: