BBC Radio 4 long wave reception problems etc.

[paulsherwin]

I think there would be less grumbling here if Arqiva and the BBC were more open about the ongoing fault, what measures are being taken to minimise the impact, and what long term solutions are being considered. I understand their reasons for not doing so but the secrecy is unhelpful.

You don't need 'hifi ears' to hear the fault when it's audibly present, and broadcasters shouldn't be relying on listening to the output to assess technical standards compliance anyway. The general public may be prepared to put up with it, and may even assume it's an inherent part of LW broadcasting, but that doesn't mean they can't hear it or that it's acceptable from a professional broadcaster.

Can you attenuate it so that the comparison is actually equal?

Not easily, they are only 10dB or so different, I was only giving a comparison of the presence/absence of spurs.

[Junk Box Nick]

This morning R4LW sounds as well as it ever does when 198 is 'well'. RTL and RTE sound fine.

The LW Tx is only 15 miles down the road and Sutton Coldfield about the same distance but I'm in a tricky reception position for FM reception from SC - and for some reason FM reception has become more awkward to achieve over time - so I still use LW some of the time.

I have used the same kitchen radio for years which now comes into the vintage category and more and more aerial waggling and set re-positioning has been required to get a decent FM signal from 92.7 or R3 on 90.5. Sometimes I have better luck tuning to one of the other two more distant FM outlets that I can hear a little further up the band. Like a lot of us there are sets all over the house and so I know the FM reception problem isn't confined to one set.

As for Droitwich I guess it's a case of keeping the old girl going until she ceases to be maintainable or it becomes politically possible to switch her off - whichever comes sooner.

In the meantime with UKVRR in an unofficial monitoring role, if we can apply a gentle nudge when things are out of kilter, without being stroppy about it, then were are providing a useful service to the wider population.

[thermionic]

One aspect that worries me slightly is that LW 198 still carries the digital switching signal for Economy 7 Radio Teleswitches for tarriff change / heating control. However, these are rapidly being changed for smart meters that incorporate the switching, and these are controlled through the mobile 'phone network.


Perhaps this is the main reason why 198 is being maintained ... what happens when the change over is complete?

SimonT.

[g8jzyian]

For those unfamiliar with radio teleswitch see the following link
http://www.radioteleswitch.org.uk

I caught a 'phone call on 198 just now, you can see the 'spurs' are second harmonic. Being twice as big (but smaller) on the 'phone bit. Modulator overloading?

[G8HQP Dave]

What do you mean by "second harmonic"? If you mean that the spreading width is roughly twice the baseband width, this is exactly what you would expect for third-order intermodulation.

If you mean that the spreading width is roughly twice the baseband width

Yes that is what I mean, thank you for clarifying what it should be called.

At the present it is just as bad...

[PaulR]

It doesn't sound wonderful either

Been a few days now, here is my latest spectrum, still there!

[Nuvistor]

Now that is interesting, this is a snapshot just taken from the online SDR http://websdr.ewi.utwente.nl:8901/m.html which looks very clean and occupying 10Khz bandwidth.

[G8HQP Dave]

Perhaps British aether is more nonlinear than Dutch aether?

[russell_w_b]

Could you compare with a SDR 'snapshot' taken between one and five in the morning when Burghead and Westerglen 50kW 198kHz BBC R4 transmitters are off-air, but Droitwich is still on-air broadcasting the World Service?

That's if Droitwich still broadcasts the World Service on LW 'after hours', of course.

[Nuvistor]

Is this to test if there is interaction between the 3 stations, the Dutch SDR not receiving Westerglen and Burghead?
I was thinking it could be intermod or overload within the SDR but your suggestion is well worth trying.

[russell_w_b]

That was the idea. There might be a slow repetitive modulated interference pattern concomitant with 'mush area' fading, althought if everything is phased up correctly this might not be so readily evident.

I'm sure the Twente receive aerials would pick up both Burghead and Westerglen over the sea-path. They can be heard in Norway after all!

[Ian - G4JQT]

Here we go again. Fine this morning, but horrid now!

SOry for not reporting recently, this is how it is now, pretty awful.

[Ian - G4JQT]

Thanks for the image. Yes, it's embarrassing...

[G6Tanuki]

Out of interest, I wonder if anyone's done an analysis of the times between this problem being fixed and it recurring again?

I'm wondering if there could be a memory-leak or something similar somewhere in the transmission-path and as time goes on a resource gets depleted to the point where there's insufficient buffering capacity so the path becomes lossy and data experiences the audio-equivalent of 'pixellation' ??

A quick measurement on my SDR screen shows the sibilance is about 20 to 30dBV down on the real sideband. Ridiculously high.