All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Mr Fowler: Over the last couple of days there has been a lot of reports of co-channel interference, with reception of French channels reported. The area affected, according to reports seen on this website is the east of England from Yorkshire southwards through East Anglia and Cambridgeshire to Kent and Sussex.
Ideally, two TV aerials should be combined using a diplexer:
Television Aerial Boosters / Amplifiers, Splitters, Diplexers & Triplexers
Unfortunately though, the PSB and COM channels used by Sudbury and Dover respectively can't be combined with a C51 diplexer as COM6 wouldn't be available (it being on C48).
Alternatively, combining Burnham and Dover with said diplexer would leave you without COM6 from Dover and without PSB2 (C49) from Burnham.
I would suggest that the Burnham relay might serve you, the coverage map on this site appearing to be wrong. I say this having looked at the photos of the transmitter:
mb21 - The Transmission Gallery
The trough antenna part way up the tower points to Sudbury which is roughly due north. The sets of crossed logs at the top are the broadcast antennas and are pointing roughly 45 degrees clockwise of the receive trough. This would make sense as Burnham-on-Crouch is to the north east of this site!
You appear to have clear line-of-sight to Dover which is 41 miles away:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
The downside is that this is over 15 miles of water which can be prone to mist which might inhibit the signal. It is also the case that your aerial is pointing towards France.
Clearly there is no given as far as receiving the COM channels goes. Despite also being 41 miles away, you don't have line-of-sight with Crystal Palace. If you did then that would be possible to diplex with Burnham or Sudbury for PSBs.
One observation I will make is that the bearing of the Burnham relay and of Bluebell Hill in Kent is only three degrees apart, and they are both horizontally polarised.
The terrain plot would suggest that you probably have line-of-sight to it at 25 miles:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
Despite this, Digital UK suggests that reception may be variable, apart from PSB2 which it thinks may be non-existant. Do take what it says with a pinch of salt, predictors never been exact.
I can't see any other transmitter that the predictor perhaps "thinks" might degrade your reception. I wonder if the beam from the transmitter is tilted low, so that it doesn't carry as far (towards the horizon), its intended service area being Kent, after all.
As Bluebell Hill's channels and those of Burnham-on-Crouch are Group B (strictly speaking Bluebell's COM6 on C54 is just outside, but that's probably neither here nor there) use your Sudbury aerial, particularly if it's a Group B one. Turn it to Bluebell Hill and see if you can receive its COM channels (and its PSBs for that matter).
The point is that by changing from using Sudbury for PSBs to using Burnham relay, you could potentially give yourself another possible source of COM channels. Even if, having turned your Sudbury-facing aerial to Burnham, you find that Bluebell Hill's COMs aren't good enough, you would still have the possibility of Dover as it stands now.
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Jenni : The Streetview photos of the building, taken August 2012, show a grid type aerial on the south end of the building and it appears to be pointing to Brighton Central transmitter, which is on the roof of Theobald House. Unless there is something between the receiving aerial and transmitting aerial it would seem inconceivable that poor reception could ensue.
Slightly anti-clockwise of this is the high-power Rowridge transmitter, which is on the Isle of Whight. It is possible that the TV is incorrectly tuned to the signal from Rowridge, which may explain why the signal is poor.
Over the last couple of days there have been lift conditions which cause signals from distant transmitters to carry much further. For example there have been reports of broadcasts from France being received in the UK.
This could explain why the signal was lost, and particularly so if your mother's TV is tuned to the weaker Rowridge signal.
Bring up the signal strength screen on BBC One. It should say that it is tuned to UHF channel 41 (634MHz). Do the same for ITV - it should be UHF channel 47 (682MHz).
If BBC is C24 (498MHz) then it is tuned to Rowridge. ITV from Rowridge is on C27 (522MHz).
If you find either tuned to Rowridge then run the automatic tuning scan through and have the aerial out for the first 30% of the scan (or until it gets past UHF channel 30) so as to miss out Rowridge. Then check that it is tuned to Brighton Central.
I assume here that the aerial is directed to Brighton Central. It would appear that reception from Whitehawk Hill might be out of the question owing to the building on the opposite side of the road.
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Tony McCully: It's the lift conditions which are causing distant transmissions to carry much further than they normally would. Don't retune unless you wish to loose these services completely or wish to see if you can pick up distant transmissions.
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Jenni: Before you proceed, ensure that the aerial is still as shown on Streetview: BN2 9PL - Google Maps
If the TV is tuned to the transmitter to which the aerial faces, and there is no issue with your mother's receiver or aerial lead then any issues with reception are down to the aerial system. Therefore you should speak to the party responsible, once you've checked that the TV is tuned correctly.
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Bob Aston: Local interference, possibly from a nearby noisy electrical appliance, perhaps running on a timer.
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Eric: It's co-channel interference caused by the lift conditions. People in the UK from Yorkshire down to Sussex and Kent have reported issues over the last couple of days.
See:
What is the Inversion Effect and why does it effect my Freeview TV reception?
| ukfree.tv - 11 years of independent, free digital TV advice
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Krista: There is nothing wrong with your equipment, apart from the fact that it is now not tuned!
The conditions high in the atmosphere have been causing distant transmissions to carry, which interfere with local transmissions:
What is the Inversion Effect and why does it effect my Freeview TV reception?
| ukfree.tv - 11 years of independent, free digital TV advice
You'll have to keep retuning until it all comes back, something which you wouldn't have had to do had you not performed a retune in the first place.
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Steve Welton: It's the lift conditions. They have been causing havock on the east side of the country from Kent and Sussex in the south all the way up to Yorkshire.
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SeeMoreDigital: Some time next year, no date is given by Digital UK.
This is because it's not on air yet, so is currently radiating at 0W.
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Thursday 12 December 2013 5:45PM
Andrea: Judging by comments posted on this site, it's affecting a large portion of the east of the country from Yorkshire down to the south east. The lift conditions are causing signals from distant transmitters to carry further then normal. In the days of analogue you'd see lines appearing on the picture, and if it got really bad you'd be able to make out the picture of the interfering signal. With digital you get the "no signal" message. Whatever you do, don't reset as all this will achieve is loss of services completely.