All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Alain: Crystal Palace can't interfere with Hemel Hempstead because they are on different channels.
I have no idea what your problem might be. It might be worth searching the internet to see if others are in the same position.
There may be a firmware update for the device or there may be new drivers for it that will cure the problem.
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Daniel Badman: Thanks for the report; it's good to hear that you have it sorted.
Different devices use different scales and have different tolerances so you can't really compare one with another.
The objective with digital is to have good quality. There needs to be a strong enough signal for it to be above the threshold for a receiver to resolve a picture.
The picture produced with a 100% quality signal with strength of 65% is the same as 100% quality with 85% strength. If a booster is connected to increase the strength, then it should be removed. "If" the quality is an issue (i.e. you get break-up) without it, then it may need to be present, but if there is good quality without it, then don't use it.
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Liz English: All receivers should have to allow manual tuning. It is bad designers that are responsible.
What should happen is that they are locked in a room with 100 of the things and told to tune them all in correctly with the "real world" problem that you are experiencing. Then they should only be allowed once all that is done.
Are you sure that it doesn't have manual tuning?
My Sony RDR-HXD870 does but it's a bit hidden. Having tuned to programme channel, e.g. ITV1, you bring up the signal strength screen and that allows selection of UHF channel. The receiver having "looked" at that channel then allows the user to add any services that may have been found.
The tricky thing here is that Bluebell's pre-switchover ITV1, C4, C5 etc is in the 20s which is where all of Crystal Palace's are. You should be able to remove the aerial lead for the first 30% of the scan to miss out Crystal Palace. However, in so doing you will miss out Bluebell ITV1. If you can put up with that or if you have manual tuning hidden somewhere, then you may be able to add it using that.
The only thing I will say about manual tuning is what it does may vary from device to device. Because receivers usually put duplicates in the 800s, other transmitters within range are often tuned in. In some cases manually tuning then achieves nothing because as far as the receiver is concerned it is tuned (albeit in the 800s). Obviously the user wants the manually tuned channel to be the main one and not thrown in the 800s.
The trick may be to get it so that it doesn't store the mux from the wrong transmitter during the automatic tuning scan, perhaps by removing the aerial for all or part.
Failing that, you may find that BBC One from Bluebell is in your 800s. There may be a facility to swap services. I will be a pain to swap all the BBC ones, so you may just have to hope that you don't get much break-up because the wretched thing has tuned to CP.
The thing is that BBC from Bluebell is now on its final power. Crystal Palace switched in April, so you probably have never tuned since CP switched over which is why you've never had this problem before.
If you find that this is still a problem after 27th, then run the automatic tuning scan with the aerial unplugged until 30% and this will miss out CP. All of Bluebell's channels will be above CP's at that time, so this should sort it.
*Unless* perhaps it is one of those pesky pieces of junk that take it upon themselves to do a full retune at some point when unattended and therefore revert to CP. If there is an option to turn this "function" off (which there isn't forced to be) then it should be turned off. If this turns out to be a problem, then you will have to cross that bridge when you get to it.
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micky, Tony, Dave: SDN (ITV3 etc) remains on its pre-switchover channel 48 on low power until 27th June. This is because C42 is currently being used by transmitters in Kent until they switch-over on that date.
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Briantist: SDN remains on C48- until 27th at 2kW (according to DUK).
It has never used C42+ which is what Tunbridge Wells used before switchover and up to 27th. The other five muxes are a SFN with TW now. SDN's SFN doesn't start until 27th.
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Peter: You can avoid it tuning to Eastbourne by unplugging the aerial for the first 30% of the scan. However, if it is one of those receivers that takes it upon itself to due a full rescan when unattended and goes back to Eastbourne, then you will have to see if there is an option to turn off that "function". If not, then cross that bridge when you get to it, but the last resort would be to fit a Group A filter. This will block out all Group A channels which are those in the 20s and some lower 30s.
If this is an external aerial or perhaps a professionally fitted loft aerial, then it may be a Group A one which makes it not the best choice for Heathfield which is Group B now.
For an explanation of aerial groups, see Aerials, TV Aerial and Digital Aerial
They drop off gradually and so a Group A will still work to some degree on channels outside of group. For some example gain curves, see Gain (curves), Again
If this is a set-top aerial or one from a DIY kit, then it is probably a wideband one and will be more suited.
If you can, try using it without the booster to see if it is sensitive enough now. C48 (SDN which carries ITV3 etc) is still on low power until 27th when it will move to C42 and go up to full power, so it may be unavailable or intermittant now.
If you are looking at replacing your aerial, then I recommend that you take a look at ATV's site. It has a page on Heathfield:
Heathfield Transmitter
Heathfield was Group C/D before switchover and is now Group B, so if you do go for a group aerial, then it should be a "B".
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Micky: This is an independent site, thus information listed is sourced from elsewhere. Mistakes can happen and I have pointed this out to Briantist who is the site's owner.
One of the problems you may have is that C47 and C49 are high power and therefore strong signals, and relatively speaking, C48 in the middle is weak. This marked difference could be the source of the problem as the high power signals could be acting to desensitise your receiver. That is it is "looking" at 48 with high power signals on adjacent channels.
This could be likened to your eyes densitising at night when bright light is shone in your direction. Car headlights coming towards you, for example, may reduce your ability to see the surroundings.
You "may" be able to reduce the level of all signals by using an attenuator inline with your aerial lead in order to increase the sensitivity of the receiver. I say "may" because in so doing you will be reducing C48, but at 2kW at only four or five miles away is still powerful so you may be able to find a sweet spot where it all works.
If you get a variable one (20dB) you can then adjust it whilst viewing the signal strength on C48. Give it a few seconds to adjust to any change you make. Then find where it is at its maximum.
Attenuators can be picked up from online sources such as eBay or Amazon for £3 or £4.
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Wednesday 13 June 2012 12:25PM
Bill: One other thing about Heathfield; COM4 (SDN) which carries ITV3 etc (see the DMOL link I gave you) does not go to full power until 27th of this month so it is likely to be unavailable until then.
This is because its final frequency is in use by Kent transmitters until they complete their switchover on that date.
A full retune will be required then, or you may be able add it by manually tuning to C42. It will depend on the design of the receiver as to what it will allow you to do.