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High pressure causing channel loss through "Inversion"

High pressure does not just bring cold at this time of year, it is causing quite random loss of Freeview and analogue reception.

High pressure does not just bring cold at this time of year, it
published on UK Free TV

There is high pressure over the whole of the UK at the moment, and this causes the Inversion Effect. This is causing people to be missing a single Freeview multiplex, or have terrible analogue reception on a single channel. The problem may come-and-go or last for several days.

For details, please see What is the Inversion Effect and why does it effect my Freeview TV reception?.

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In this section
Official aerial installers guide to the TV spectrum future1
Which free digital TV system will give me the most reliable reception?2
Digital Region Overlap3
Freeview reception has changed?4
Two frequency interference 5
Single frequency interference6

Saturday, 24 March 2012
8:51 PM

Angrybird, I asked in a local TV dealer in Surrey if they were also experiencing poor digital reception at the moment. Answer was "of course we are and we've been told by a rep that the reason is the transmitter power output has been reduced whilst they are making modifications prior to DSO (our transmitter is Crystal Place). We've had high pressure and inversions many times over the last 5 years but always maintained a good signal. This time it is coupled with low power outputs, hence no reception.

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Graham's 8 posts GB flag
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S Rogers
8:52 PM

My screen kept going blank throughout last evening, and now again tonight - the channels are just freezing and the little aerial symbol (meaning loss of signal) keeps appearing. I re-scanned my box and all the ITV/ch4/ch5 channels were replaced with French ones. What is going on???

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S Rogers's 1 post GB flag
Dave Lindsay

9:03 PM

S Rogers: As above. Signals are carrying further than they normally do due to the inversion effect caused by high pressure.

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Dave Lindsay's 5,724 posts GB flag
9:08 PM

Rubbish service in ITV and poor reception from BBC.
NOT GOOD ENOUGH. Just trying to force us to subscribe to Mr Murdocs shoddy outfit

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Phil's 1 post GB flag
10:18 PM

Not sure what sort of TX site you worked at Angrybird but I'm surprised you don't recognise the problems anaprop causes at UHF. You certainly can't go round just turning up the wick without calculating how it will effect the rest of the network, both in this country and across the Channel. Last weeks tropo produced some of the 'best' conditions for a few years for those interested in DXing. Some of the distant signals not normally seen reached incredible strengths last week. I had a number of French TNT multiplexes over riding my semi local Brighton TX. All this has of course been going on for years, everyone will be familiar with the lines and patterning seen on analogue TV but apart from a brief period of pixellation there's little between perfect picture and no picture on DTT. How they expect the proposed SFN to cope with tropo I can't imagine. The DXers amongst us always knew this would happen during tropo, the digital signal is much more susceptible to interference so I'm not surprised those 'in charge' of pushing through DSO didn't want to highlight the problem.

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Bob's 1 post GB flag
tia c
10:55 PM

gosh im glad i found this site, our telly played up the other night, might have been last night (broadstairs) and i seem to remember last year we kept losing signals on itv to the extent that i kept missing bits of the x factor (a disaster)

if forgot about analogue so am now watching itv on that

im surprised to come into the site and find that theres no announcement that the signal is bad

its the itv channels, the bbc ones seem ok

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tia c's 1 post GB flag
Sunday, 25 March 2012
John Beeston
9:54 AM

Re my posting on 22.3.12 Can anyone answer the questions (a) will this rubbish reception improve after switchover
(b) will it still happen if I get freesat?

Cheers John

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John Beeston's 8 posts GB flag

10:56 AM

John Beeston: When switchover takes place the PSB muxes will use the frequencies currently used by the analogue services, so if you currently have good analogue reception you should have good digital reception, at least on the PSB muxes after switchover. The power of all muxes will be 20kW on all muxes, which is greater than that normally used to cover the original analogue service area. With regard to Freesat (or Sky), no the conditions that affect Freeview reception do not affect satellite reception. However satellite reception can be blocked by thick clouds, heavy rainfall or snow on the dish/LNB. Remember too that some channels that are free-to-air on Freeview are subscription channels in the Sky line-up on satellite.

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KMJ,Derby's 1,811 posts GB flag
paulo C
11:05 AM

No Tv reception East Grinstead for past 18 hours and patchy reception all week. I am given a pat on the head told not to worry and it's down to the "inversion effect". We weren't told about this when the great digital switchover was announced. Digital Radio next - no chancee if this is the standard of service I can expect.What another con by our rulers in Whitehall!

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paulo C's 1 post GB flag

11:16 AM

tia c: If you are using the Bluebell Hill transmitter Mux2, which carries ITV1, is currently using a frequency which is more susceptible to interference from other transmitters. After switchover on 27th June 2012 it will change to the frequency currently used by analogue ITV1, with power increased to 20kW, up from the present 4kW.

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KMJ,Derby's 1,811 posts GB flag
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