All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Richard: If your receiver is finding other channels, and those channels fall outside of the range used by Crystal Palace, then you can avoid them by using the unplugging aerial trick I mentioned.
If there are other transmitters that are within the "target" of say 21 to 30 for Crystal Palace (I allow a few channels either side to ensure that they're all picked up), then you may have to revise your plan.
I don't have first hand experience of these Humax devices. However, I have read that when tuning some HD tuners you need to select the HD mode when tuning in the HD channel, that probably being "DVB-T2" as opposed to "DVB-T" which is for standard definition.
I wonder, if you are doing it manually if you have to set the mode manually and that it does not automatically assume the correct mode. This would perhaps explain why it does find a signal, but just no quality.
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Paul: I presume that the transmitter is Hannington.
If you are carrying out repeated automatic retunes in the hope that this will solve the problem, then this is unlikely and more likely to be a waste of time and effort to resolve the problem.
The first thing you need to do is to confirm that the channels being picked up are those from Hannington and not from another transmitter. Having established that they are all correctly tuned, then you should not retune because that will achieve nothing except perhaps undoing what has been done. Where there is poor reception on channels that are tuned correctly, then the problem must lie elsewhere.
Refer to "After switchover configuration" here: Freeview multiplexes | ukfree.tv - independent free digital TV advice
You will see that there are six groups or multiplexes, one of which is HD. For one of the services from each multiplex, bring up the signal strength screen and ensure that the UHF channel that it is tuned to is that of Hannington:
BBC One = C45 (23 is Crystal Palace;55 is Midhurst)
ITV1 = C42 (26 is Crystal Palace;61 is Midhurst)
BBC One HD (if applicable) = C39 (30 is Crystal Palace;58 is Midhurst)
ITV3 = C41 (25 is Crystal Palace;62 is Midhurst)
Pick TV = C44 (22 is Crystal Palace;59 is Midhurst)
Yesterday = C47 (28 is Crystal Palace;50 is Midhurst)
Should it turn out that any of these are not Hannington, then run the automatic tuning scan with the aerial lead unplugged, plug in at 30% and unplug at 56%. This will have the aerial unplugged for Crystal Palace (which is below 30%) and for Midhurst (which is above 56%) and plugged in for Hannington.
Having done this, then check each of the above to ensure that they are Hannington. For any that are missing, use manual tuning to add them if it will allow. If it manual tuning won't allow them to be added, then make a note of them and add them later.
If the problem of poor signal prevails, even though you are tuned to Hannington, then I suggest that it could be too high a signal level which is overloading your tuner. See: Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice
The thing with Hannington is that before switchover, the amount of signal it put out in an easterly direction was restricted. So the signal you got at your side of the transmitter was less than someone on the opposite side at the same distance.
Now switchover has completed, the signal is omnidirectional. Hence the difference between the low power pre-switchover and high power post-switchover signals at your location is quite great. Consequently, in order to pick up the weak pre-switchover signals you may have had an aerial installed (perhaps with a booster) that was sensitive enough for the weaker signals, but is now OTT.
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Elaine Fox: Please can you give an idea of your location so the signal in your area may be predicted, this being preferably in the form of a post code or nearby post code (of a shop for example)?
The only thing I will say is that if you are close to the transmitter, then the signal will be much stronger and could be overwhelming your receiver which could be the cause of what you describe. An idea of your location may give us an idea of how likely this might be the case.
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Big Mart: Where signals from more than one transmitter are picked up by the aerial, different pieces of equipment can decide to go with different transmitters.
Go to BBC One HD and then bring up the signal strength screen. For Crystal Palace the UHF channel used for HD services is C30.
According to Digital UK Tradeview predictor you may be able to pick up Sandy Heath (C21), Hannington (C39) or perhaps Hemel Hempstead (C47).
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George Silvester: In order to help with reception problems, knowledge of your location is necessary in order for a prediction to be made of the likely strength of signals in your area. A post code is preferred; give on of a local business if you don't wish to give your own.
When did this problem start? Are you in the London region and have therefore completed switchover last Wednesday? Did the problem start then?
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MJ: Digital UK reports that Rowridge digital TV is "liable to interruption":
Digital UK - Planned Engineering Works
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threewheels: What's the make and model of your receiver? Due to an issue, some are unable to receive channel 28 from Crystal Palace.
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Robert: I don't think so.
The reason that I suggest unplugging the aerial lead for part of the scan is because the automatic tuning process may produce to "wrong" results, i.e. the set of channels that the receiver decides to use as the "main" ones are not those from the transmitter to which the aerial faces.
The first thing that is done during automatic tuning is to scan frequencies from low to high and see what's available. Having done this, the receiver needs to decide (where duplicates are found) which ones to use as the main ones. The rest are usually put in the 800s. It is the process by which the decision is made that can vary between receivers and hence the outcome of what any one device may choose to be the "main" set may vary to that of another device on the same aerial.
Having chosen "wrong" channels, the user is then watching a transmission broadcast from a transmitter other than the one which the aerial faces. So it's not surprising if poor reception does ensue. It is therefore necessary to, somehow, get the device tuned to the correct channels. The same issue could occur in the days of analogue with automatic tuning.
Where the wrong channels that the receiver decides to go with are outside of the range of those used by the desired transmitter, then a simple way around the problem is to unplug the aerial so the device never gets to "see" them during its scan.
If you click the Digital UK (DUK) Tradeview link next to your posting, it will bring up the DUK prediction for transmitters you may be able to receive. You say that you have some services by 30% of the scan. The scan runs from channels 21 to 69, so you can convert to percentage and vice versa. At 30% it has completed looking in the 20s and there is apparently one transmitter in that range which is Chiseldon.
Looking at the predictor for your location, if you do the unplugging aerial trick, then the channels used for Mendip are interleaved within those of Oxford.
What I would say is that it is perhaps good practice to check that the main channels are the desired ones. Refer to "After switchover configuration":
Freeview multiplexes | ukfree.tv - independent free digital TV advice
Check the signal strength screen whilst on one of the services from each group (multiplex). Ensure that the UHF channel given is that of the desired transmitter and not another one.
As you have already done this, and confirmed it is channel 62, then this would appear not to be the issue (at least for this particular multiplex).
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paul sheen: What happens when you manually tune depends on the design of the device. What you hoped it would do is replace the incorrect main channels with those of your desired transmitter.
However, if the multiplexes from the desired transmitter have already been stored in the receiver's memory (usually put in the 800s), manual tuning may just do nothing because as far as the receiver is concerned, the channels are already tuned.
I assume that the London broadcasts that you are picking up are from Crystal Palace which switched over to digital on Wednesday. These are all on frequencies within the first 30% of the scan. If the Anglia transmitter you are intending to use is Sudbury, then its channels are higher up, so if you run the scan with the aerial unplugged for the first 30%, your receiver won't get the opportunity to "see" the signals from Crystal Palace.
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Saturday 21 April 2012 5:36PM
Richard: Check that your receiver is tuning to Crystal Palace and not Wooburn which is nearly on the same trajectory.
For each of the following bring up the signal strength screen and it should tell you the UHF channel you are tuned to:
BBC One = C23 (Wooburn is 48)
ITV1 = C26 (Wooburn is 56)
BBC One HD = C30 (Wooburn is 52)
If this proves to be the problem, then when running the automatic tuning scan, unplug the aerial when it gets to 30%. All of Crystal Palace's channels are below 30% and Wooburn's are above.
On the basis that all have 100% strength, I would wonder if the signal level is too high if, having checked, you find that you are indeed receiving them from Crystal Palace. This is perhaps a little surprising as you are nearly 30 miles from the transmitter and you don't have clear line of sight with Berghers Hill being in the way.
If it is too much signal from Crystal Palace, then have you got a booster connected in there? If so, remove it or reduce its level of amplification if possible.