I had to involve OFCOM, the noise got so bad. Here is a recording of an empty channel in the FM broadcast band. 99.0 MHz to be precise, though it doesn't matter too much which part of the band you tune to.
Click to hear the Interference
0:00 - 1:25: Beaming east on 99.0 MHz. From 0:15 I rotate my beam from east
to south-west and back again.
1:26 - 1:46: S9 of noise on the 4m band. I am tuning from 68 to 74 MHz at the
beginning of this part.
1:47 - 2:05: The hashy effect of the noise when it's at its quietest. The fluctuation is
caused by the AGC of the Sony XDR-F1HD tuner.
Even with the noise at its weakest it is strong enough to block out continental signals which would otherwise be noise free. It will also create a hashy sound in the background of BBC local stations. It's a silent killer in a sense because it doesn't always show up on the signal meter, depending on which tuner I use. Tuning the same range on my Icom IC7000 with the same my rooftop band 2 antenna reveals this is an S9 noise level - no preamp used.
The noise signal can be stronger, creating as much as "two bars" on my Sony XDR-F1HD tuner - equal to a fully quieting stereo signal and S9+ on the IC7000.
OFCOM say there is little they can do for me because the noise "isn't severe enough". How "severe" does it need to be? It is already obliterating the 4m band and probably the 6m band too (I don't have an aerial installed for 6m at the moment).
Thanks OFCOM for nothing!
If that's not severe John then bad must be bloody awful.
ReplyDeleteIt is severe. It's intermittent too, which makes it a sod to track down. It's also an abuse of a considerable part of the radio spectrum, affecting both BBC broadcasts and the amateur radio bands.
ReplyDeleteEven my local Belmont transmitter can be affected with the noise making a mess of the audio. If that isn't bad enough then I don't know what is.
How about the 4m band? The noise can register as high as S9+40 dB there! I thought the amateur bands were supposed to be protected?
I don't like to use the statement "well, it could be worse", as OFCOM did. What a meaningless statement. Of course it could be worse, but it could also be GONE!