All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Colin: According to the comments on this page, that model isn't likely to be able to receive all channels from Belmont:
ZERO digital channels on Panasonic TV after DSO - Technical - Digital Spy Forums
It appears as if it might be the negative offset problem in 8k mode.
8k mode is the mode of transmission used after switchover (it is 2k mode before).
A TV signal is transmitted on a channel which is at a particular frequency. For example, channel 30 is at 546MHz. C30 with a negative offset (C30-) is at a 545.8MHz which is a slightly lower frequency than the "centre" of C30, but higher than C29.
It is known that ITV3 is carried on C30- from Belmont, so if the problem is that it won't pick up negative offset channels, then I would expect ITV3 to be missing as well.
Yesterday is on C60 and according to Digital UK Tradeview, this also has a negative offset, although some other sources don't say that it has such an offset. Perhaps it does have an offset, but this was not originally planned which is why in some places it isn't mentioned.
Refer under the heading "After switchover configuration" here:
Freeview multiplexes | ukfree.tv - independent free digital TV advice
This shows the five standard definition groups (BBC B carries HD services). One of these is "SDN" which carries ITV3, so if it is missing, then I expect all others on that line to be as well. Similarly, Yesterday is on ArqB which also carries Film 4, ITV4 and others.
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Colin: I should point out that the problem may be that the TV cannot tune to 8k signals that have a negative offset.
Not all transmitters have any channels with negative offsets, but in the case of Belmont it is definately so with SDN and probably ArqB.
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Deep: It might be worth noting that COM6 is on channel 50 from Midhurst. It is the lowest channel number that is used now.
Before switchover, the lowest one was 55 which is now the second lowest.
Perhaps your aerial system is filtered so as to only allow channels or a range of channels used by the designated transmitter. If this is the case, then it will need adjustment in order to let the COM6 signal through.
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Colin: Other than manually tuning to C60 (if the set allows), I'm not sure what else to suggest. Perhaps one of the pros could suggest something.
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Roger: I don't think that you will be able to receive from Reigate at your location. I think that the most likey transmitter is Crystal Palace which is 22 degrees anti-clockwise from Reigate and is horiztonal.
If you have re-aligned due to not being able to pick up the COMs (that's the Commercial channels including ITV3, Pick TV, Yesterday, Film 4, Dave etc) from Hannington, then the reason for this is probably down to the Chepping Wycombe relay transmitter using the same channels and therefore drowning out Hannington's COMs.
You should be aware that if your aerial is a Group B one, which it might be for Hannington, then it won't be optimum for Crystal Palace which is Group A. If it is a wideband aerial (or Group K), then it will be fine (although widebands aren't as sensitive at the bottom of the band (Group A channels)).
See:
Aerials, TV Aerial and Digital Aerial
Gain (curves), Again
If it is the case that you can't get the COMs from Hannington, then you could theoretically combine an aerial on Hannington and one on Crystal Palace to give you Meridian with Commercial channels from CP.
You should be able to identify which transmitter(s) your receiver is tuned to by looking for the UHF channel number on the signal strength screen.
There are five full Freeview standard definition channels and one HD one. Refer to each transmitter's page for details of the channels used by each.
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Deep: You need to think about how you might prove (with good certainty at least) whether the problem is the aerial system.
Some ideas:
- Do you have other receivers (TVs with in-built Freeview, PVRs etc) that won't pick up C50? Try manual tuning to C50 for those that allow. They may (it depends on design) give you an indication of signal strength when you do this. It may indicate a low signal, and not one that it high enough to produce a picture.
- Ask you neighbours if they have the same problem. Bear in mind that some may not use the terrestrial aerial system, if they use a satellite service. This will perhaps provide the most positive proof, although, they need to be certain that they are missing these services.
- If you have a set-top aerial, try it. The aim is to prove if you *can* receive C50; a negative result isn't necessarily helpful. If you have all other channels (except C50/COM6) tuned in correctly, then use manual tuning to add it; don't do a full retune. Once you have it stored, then don't retune as your problem is lack of signal and not incorrect tuning. Having tuned it in, connect it to the aerial system and see if it works.
You then need to contact the organisation responsible for the aerial system. In a block of flats, this is probably the landlord.
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Steven: Assuming you are receiving from Sudbury, which would seem the most likely, then you should be aware that the three Commercial multiplexes are on low power until 27th June when a retune will be necessary as they each change channel.
I suggest that your problem could be the difference between the high power (Public Service) channels and the Commercial ones.
The high power ones probably act to desensitise your receiver thus making it less sensitive when attempting to pick up the weaker ones. Different equipment has different tolerances.
Until 27th June, you "may" be able to restore Film 4 (and others on ArqB which is on C63 until then) by placing an attenuator in line with the incoming aerial lead. The objective being to reduce the level of the high power signals so as to increase the sensitivity of the receiver, but in so doing you will be reducing the level of the low power signals as well. You would be looking for a sweet spot where all channels work. There is no guarantee that you will get to such a solution as obviously you may end up attenuating the weak ones too much for them not to work.
You can pick up a variable attenuator (usually 20dB) online for around £3 or £4.
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John Bates: The delay of two weeks will affect ITV3 and the other services carried on the "SDN" multiplex. See here under the heading "After switchover configuration" for those carried on SDN:
Freeview multiplexes | ukfree.tv - independent free digital TV advice
The reason for the delay is because the Dover transmitter is currently broadcasting on the same channel/frequency that will be used by TW for SDN after it switches over (Ch42). Dover completes its switchover on 27th June and it is then that it relinquishes use of that channel.
Thus, the interim low power from TW is so as to protect against causing interference to some people who are receiving C42 from Dover.
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Ted: If your aerial is at 51 degrees, then you're not pointing it to Rowridge. I guess that you're on Mendip.
A more specific location might help us, e.g. post code or nearby post code. It may also be helpful to see where nearby aerials are pointing for ideas as to what might be possible and what might not be.
As a test, I found the post code for the Anchor Inn and put it into the Digital UK Tradeview predictor. It suggests that Brushford transmitter is the only one. This is a Freeview Light transmitter as it only carries Public Service channels.
So what transmitter is your aerial pointing to *and* what channels has it tuned to? The latter part of the question will help us establish which transmitter the signal(s) are coming from.
Refer under the heading "After switchover configuration" on this page:
Freeview multiplexes | ukfree.tv - independent free digital TV advice
For full Freeview, there are six multiplexes, one being for HD services.
So, for the first service in each one, go to it and bring up the signal strength screen and read off the UHF channel that it is tuned to.
E.g. Go to BBC One, bring up the signal strength screen. If it says 61 then it's Mendip, if it is 27 then it's Brushford, 26 is Stockland.
Then do the same for ITV1, BBC One HD (if applicable), ITV3, Pick TV and Yesterday. Brushford doesn't transmit the last three.
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Friday 11 May 2012 5:43PM
andrew watson: I don't think that you are going to get anything from Tunbridge Wells until switchover.
One of the main issues you have to contend with is that it shares some digital channels with Bluebell Hill before switchover. The Digital UK Tradeview predictor (click the link next to your posting) thinks that Bluebell will be good where you are. Plus TW is on very low power to avoid interference.
After switchover, the situation will be different and Tunbridge Wells is expected to be excellent for you.
If you have a set-top aerial, you "may" find that you are able to receive some level of service from Bluebell now, until TW completes switchover on 13th June.