All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
steve j: WRT the issue with your Logik TV, I would certainly discount the obvious such as being tuned to the wrong transmitter.
The links which jb38 has provided are to ATV's site which contains a wealth of information on this stuff.
Other suppliers and products are available. I came across this one selling the 30 element Vision log at a very competitive price:
VISION Log Periodic W/B (30 Element) > AerialSat.com
They also do the "Super" 40 element model which I believe is the model that ATV sell as their "Log 40".
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Scott: I would wait and see.
An aerial's gain does not drop off suddenly. A Group B aerial is designed with a particular gain so as to be classified as "Group B".
The more the gain of your aerial "in group" is greater than is actually needed, then the more the "out of group" gain will be sufficient.
So in actual fact, it could be that the gain of your aerial slightly out of group is more than enough.
If you get a yagi aerial, then I suggest that you get a Group K one as wideband incorporates C/D as well, which as you say, is a compromise. On the basis that the powers that be are busy clearing 61 to 68 to sell off to the mobile operators I would think that it's safe to say that any transmitters that don't currently use C/D channels will not be using them in the future.
If you are in a good enough signal area then I suggest that you get a log periodic which are usually wideband but have a much much flatter response than yagi widebands. They also have a much neater polar response than yagis which means that they are less likely to pick-up reflections that might be present where the signal is stronger:
Aerial Polar Reponse Diagrams
Vision Products does a Group A log and a Group E log, but not a Group K one so it will have to be wideband.
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Scott: Read up on Sorites paradox
Sorites paradox - Wikipedia, the free encyclopedia
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Ray Harman: The first thing I suggest that you check is that your TVs are indeed tuned to Tacolneston for BBC and ITV.
Bring up the signal strength screen on BBC One; it should say that it is tuned to UHF/RF channel 55 (for Tacolneston). Other possibilities may be C46 for Norwich Central or C44 for Sudbury.
For ITV, Tacolneston broadcasts on C59 whereas Norwich Central is on C43 and Sudbury is on C41.
If it turns out that this is the issue, then you will need to wipe the tuner's memory such as by running the automatic tuning scan through with the aerial unplugged. If there is manual tuning, then use it; for Tacolneston the channels to tune to are: 55, 59, 62(HD), 42, 45, 50. (On 1st May this year C62 will change to C50 and C50 will change to C39.)
If there is no manual tuning, then it will be more tricky. On your automatic tuning scan, have the aerial unplugged for channels in the 40s (unplugged until 60%). This should give you BBC and ITV from Tacolneston without COM (Commercial) channels (ITV3, Pick TV, Film4 etc) and this is because those channels broadcast on frequencies close to the unwanted BBC and ITV ones. If there is a function to "add new services", or similar, which carries out another scan whilst not wiping what's already stored, then run it.
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fred davies: The Buxton transmitter is never likely to transmit more than the Public Service channels it currently carries. See here for an explanation:
Londonderry (Northern Ireland) digital TV transmitter | ukfree.tv - 10 years of independent, free digital TV advice
Unless you can receive the Commercial channels (those that don't broadcast from Buxton) from another transmitter, then you won't ever get them. As such, Freesat may be a solution for additional channels.
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Lesley: No because there is no 4G signal broadcasting in the frequency range that is likely to affect some TV receivers. This is because the spectrum has not been auctioned off yet.
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Mark: Such questions are like asking how long is a piece of string? It is quite impossible to give any exact answer.
If any network operator is about to upgrade to add 4G to one of its base stations, then it will not be doing so in the 800MHz frequency band as it would be breaking the law.
It is 800MHz signals that may interfere with TV reception as they are just above the frequencies used for TV. The licences for such services have not been granted yet.
However, if a 800MHz base station were to operate on the roof then it would seem a likely bet that it might cause issues with the TV reception, particularly as the TV aerial is probably not too far away.
But as you are using a communal aerial system it will be down to whoever maintains it to have a filter fitted. Indeed, it may be the case now that the system is filtered to only let through channels (frequencies) used by your transmitter hence it may be OK.
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k cornish: Because the Commercial networks don't see it as a worthwhile return to pay for the transmitters to such small populations.
See here for an explanation:
Londonderry (Northern Ireland) digital TV transmitter | ukfree.tv - 10 years of independent, free digital TV advice
All you can do is investigate the possibility of receiving the full service from another transmitter such as Idle, Emley Moor or Bilsdale.
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Steve Flynn: I think we covered this one when you made your posting before DSO. Haslemere relay transmitter is co-channel with Crystal Palace's COMs.
Not sure whether a phased array might help:
http://www.wrightsaerials….pdf
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Friday 8 February 2013 7:34PM
Bruce: Unfortunately not. See here for an explanation:
Londonderry (Northern Ireland) digital TV transmitter | ukfree.tv - 10 years of independent, free digital TV advice