Can any one give some hints on this?

[VK2MUS]

http://www.oztralia.info/Home/interferance.aspx

I have isolated all the power circuits , isolated all the computers etc this sound does not appear to be coming from the house. It follows a set pattern of 5 secs on and 30 secs off. Its a strong signal on 20 and 10 meters not right across the bands ie on 20M it is 14.070 only. I closed down each power point , then closed down each power circuit, swapped computers to run DM on - closed down and pulled the plug on every computer etc The house on the south is empty the house to the north I checked nothing that would give the pattern.\

I can null the interference with the seperate noise cancelling unit however to null it out completely I get fade on the signal I am trying to decode.

am lost as to what it is.
the url has a waterfall graphic of the sound and there is a wave file of it.
John

[VK4TJ]

That is "Over The Horizon Radar", John, and it could be coming from just about anywhere in the world. Not much you can do about it except file an interference complaint with VK3MV, the Region 3 Intruder Watch Co-ordinator.
73
John VK4TJ

[VK2MUS]

thank you - I pulled the place apart today checking every thing except the OTHR. I have others talk about it but had never heard it - you learn some thing every day

[VK2GOM]

Hi John, just looked at your picture - yes, nasty old OTHR again looking for incoming boats!

Not sure which country that is from though on 20m? I have seen the 20m one now and again whilst trying to operate JT65. 30m gets plagued by an OTHR in Cyprus. Quite often they are military operated. I did hear of one (can't remember all the finer details) that was eventually forced to move frequency out of the amateur band.

73 - Rob VK2GOM / G0MOH

[VK5ZD]

Here's another mystery for someone...

About half-way through the audio sample above you hear what seems to be a carrier moving very quickly up in frequency. It's only audible for a fraction of a second, but I come across them quite often when listening to HF. Does anyone know what it is? Maybe some kind of chirp radar, perhaps?

73
Iain

[VK2MUS]

Here's another mystery for someone...

I get these fairly often - then tend to be common for a day or so then dissapear then reappear a week so so later . On my setup they only started to be heard when I switched over to the Vertical so the extra height may have made the difference - the noise canceller does not hear them so they are not nulled I am putting up a different 'noise' antenna next week so they should be nulled out - actually they do not upset the digital mode decoding as did the OTHR. That OTHR signal on 14.070 has now stopped (after a week)

[VK2GOM]

...probably chirp sounders? They are used for propagation monitoring.

I often see them on my SDR Rx as a ramp moving up in frequency fairly quickly.

I saw some software once to tune your rig to track them, and monitor received signal real time as the chirp rises in frequency.

73 - Rob VK2GOM /G0MOH

[VK8DOD]

If your SDR picture shows you a ramp, its a vertical incidence sounder or oblique incidence sounder. There are a number of transmitters situated around the coast to aid propagation monitoring.

[I2NDT]

This should be the "notorious" Cyprus radar:

http://maps.google.it/maps?q=cyprus&hl= ... 6&t=h&z=18

It used to interfere my 30 metres QRSS grabber in the past...look at the first and second image here:

http://digilander.libero.it/i2ndt/Novem ... e_2007.htm

i2NDT Claudio

[VK2TDN]

This should be the "notorious" Cyprus radar:

i2NDT Claudio

Either that or the beloved (NOT) Bejing Buzzard OTHR

Dave
VK2TDN