Wednesday 24 March 2010

Hunting for noise

The other evening I had to take a walk to the postbox at the edge of our housing estate. I took a small portable shortwave receiver with me, tuned to around 11Mhz to see if I could get any idea of the source of the PLT noise that I have been picking up here.
I think I have found the noise, coming from a house in the next street, I would estimate about 100 metres from my QTH. Certainly the awful PLT noise is receivable outside the house even with the telescopic antenna collapsed.

I should emphasise that (Luckily) this noise does not affect the amateur bands, but in parts of the broadcast HF bands it is quite bad. For example on 11620Mhz this afternoon it is S9.
At least if I decide to report this problem to Offcom I can now give them a general idea where the noise comes from. It is a pity people are using these devices and I wonder why they are in use. Surely a wireless system would be better for distributing internet around the house?
Here is the PLT noise on the Digpan waterfall with my TS450 on 11620Khz.


  1. Hi Kev,

    I guess Ofcom may be more interested if the interference is caused to a protected service like a broadcast band?

  2. Hi Ian,

    I am led to believe that if the interference is in a recognised shortwave broadcast band it can be reported. I may be wrong there, I will do a bit more research.

    73 Kevin

  3. I think these devices have notches to limit interference to the ham bands, which seems to imply that "short wave can go to hell".

    As to the reason for their existence at all, I too would like to know. Surely most people use laptops these days, and wouldn't want them tethered to a mains plug for internet access.