My computer has not been off for a couple of weeks at least now due to
the activity on 8.9kHz.
Uwe DJ8WX is regularly on overnight on 8.97022kHz and a good signal in
the UK. Chris G3XIZ is the latest station I know of to have produced a
good RX trace of Uwe using his M0BMU Loop and Amplifier.
Ossi OE5ODL is making improvements to his TX set up and is now often
visible in the day and at night in the UK. Ossi’s TX shows a
characteristic slight drift HF, good for identification when the signal
strength is low.
Chris G3XIZ plans TX tests again this weekend with possible kite or
balloon supported antenna, so get those RX’s ready.
My RX signals can be seen most days on my Part Time Grabber Page please note that being a simple, cheap skate, part time grabber you the viewer have to do some work, when you want the page updated you have to refresh it yourself, oh come on its not hard work and there is an advantage over an auto refresh page which can get stuck and catch out the un-wary (me), and cause you to make a fool of yourself (me), yes I have got the T Shirt.
If I am updating my Grabber page this is the ‘live’ view of what I am receiving right now.
Right Click and select ‘View Image’ for full size.
The identifiable trace from Austria on 8.9kHz yesterday may have been more visible due to the noise survey I did and some logical steps taken the day before. Often my Grabber will be in ‘test card’ mode sometimes with a still, other times a live display, of my wideband profile which is now improved.
Yesterday Ossi OE5ODL Austria was just strong enough to produce a faint trace on my receiver on 8.969977kHz.
The Capture shows his signal rising slightly in frequency then falling again. The monochrome colours make for a better picture, it really is clearer live, honest. Seeking and confirming the weaker traces is an eye boggling task at times, Ossi’s curved trace below starts to the left and curves upward, it actually stops just after half way across then the noise level rises. A little trompe l’oiel occurs across the picture and the brain completes the shape with a matching downward curve.
For information past and present G3XBM’s Sub 9kHz Site is invaluable.
Sooner than expected I took my portable probe on a VLF noise survey walkabout. Vast quantities of Mains harmonics from computer and other domestic gear come from my neighbours either side.
In the road the levels are less, but visible, with radiation noted from Telegraph poles in varying strengths like this. Roll on fibre optic broadband.
A reduction of noise on my received signals was made by earthing alterations.
DJ8WX continues to romp in, maybe slightly improved since the alterations. The following map gives a very accurate indication of the distance from antenna to antenna location.
Well what do you expect really? The 50Hz Mains supply surrounds me, I actually feed the supply to my neighbour via a cable at eaves level that forms a 1/2 turn round the house, the cable passes above my shack window. I also surrounded by houses with a similar supply system.
Mains harmonics can be seen in my VLF range, some I think, by their behaviour are propagated over a distance from their source. From where, I shall try to find out, this may involve that ‘fool up the road with the aerials’ wandering round my garden the streets and adjacent fields with a long pole and Netbbook. Ah well last time it was with my long 23cm Horn Antenna.
I downloaded the official map of the HV Grid cables and added the Electric Railway line.
I am still completing the building of a portable probe, when ready i wonder if it would be a good idea to don a white paper suit and wellies before I go on the prowl.
Learning from those with lots of VLF experience,I find that the Noise Profile is most important on 8.97kHz, then you have to interpret what you see and try to improve any problems.
It may help to move to Iceland, TF3HZ has a near perfect profile. Halidor runs a Grabber so it’s on the web for all to see.
DL4YHF also runs a Grabber his Spectrum from Zero to 24kHz is on the web too.
I thought maybe the best way to see mine, scan up and down and compare is to put them all here.
So basically like a lot of stuff on my blog it is for my use, if you wish to look enjoy.
During an overnight test by G3XIZ in the week I was sure I saw a few well spaced pixels in a straight line from him on the correct frequency not enough to claim reception though.
Today Chris tested again, I reduced my FFT resolution to 423uHz and was rewarded with instant results. Not strong and fighting a high noise level once the rain started in the early afternoon.
Details from G3XIZ of his transmit set up :-
Frequency: 9.090 909 kHz (10.000 MHz / 1100) locked to Droitwich
Mode: Constant carrier
Power: 100 watts RF
Aerial: 40m inverted ‘L’, height 10 m
Aer current: 0.18 A