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All posts by Chris.SE

Below are all of Chris.SE's postings, with the most recent are at the bottom of the page.


Richard: you are wrong. The signal has not been DELIBERATELY underpowered in the way you imply. The strength was determined by what was possible without causing undue interference to the existing analogue services and the other other digital services around the country (& abroad). Until DSO it was not possible to start increasing power and even where DSO has taken place not all MUXes at some transmitters are on full power yet until switch over in other regions has occurred.
Mendip and Oxford are two such examples where COM muxes have yet to go to full power.

Until transmitters and their antenna have been converted & DSO occurs, compromises have to be made. This can mean some locations can not get reliable signals. Indeed there were/are many areas that could not get any digital signal until local relay transmitters were switched over. Because of the work needed at the mast at Beckley to ensure good coverage after DSO, transmission has to be done from a temporary mast for a period of time. This was longer than originally planned because of the fire on the main mast. This also meant poorer signals for some.

If there is any criticism to be aimed it could well be at some dealers or aerial installers for not fully informing people or indeed for individuals not seeking adequate information, about the pre DSO situation and what may happen at DSO. To rely soley on Digital signals prior to DSO in an area that was suffering poor signals at the time was not sensible.
Even where people needed to purchase new equipment, for a TV set that didn't have an analogue tuner in addition to a digital one, such a set could have been fed a picture via a scart from a then existing VCR for example.

There have been minor hiccups as DSO has progressed, but generally speaking things have gone well especially in light of the mammoth undertaking and the need of the public to purchase new equipment and aerials.


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Ralph: I've been beaten to informing you about Freesat. That said, West Swindon is one of the more problematic areas, but as you haven't provided a post code no one can advise how reliable a signal you might expect from Oxford now DSO has occurred or indeed Mendip.

The PSB muxes at both Mendip and Oxford are now on full power (100Kw each), but the COM muxes are on restricted power until March/April next year until other regions switch over.

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stephen: hi, are you sure your model has an in built HD tuner? Give us the full model number and we can check.
Did you get the HD channels before DSO?

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John: you might also be picking up the Mendip MUX for ITV etc.
Without a full postcode, can't tell you how reliable a signal you should be getting from Oxford (or Mendip). Did you get all the MUXes before the switchover?

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Briantist: Hi Brian, could you update the Power info for the COM muxes, all restricted to 12.5Kw until April 2012. Thanks.

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As you say Mike, a minor quibble. I should have used the word Antenna instead of mast, but was hurriedly trying to keep the explanation simple in light of the lack of knowledge and other things to get on with ;)

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Mike: nice explanation
jb38: what do you mean - amateur, that's a totally professional way of assessing the signal strength in the absence of a signal strength meter :-o :)

Suzanne: Hi, I should have a lie down if it helps, and stop apologising ;)
If you don't have a bit of flex handy, try using just a 'flylead'- that's the short 1-1.5m coax lead that you'd have used to connect your old VCR to old TV, or aerial wall socket to TV etc. I can't remember which board, but someone had such a strong signal that worked for them!
I see you got a good explanation from Mike, hope you understood, you did ask :)
On the subject of changing your aerial - no point, attenuators & set top aerials are cheaper and all result in the same thing - less signal being fed to the set/box.

Briantist: single frequency interference is unlikely as Suzanne has no equipment, the only possibility would be next door's Sky box, even that's unlikely. Gross overload is the likely cause and jb38 gave a nice illustration.

So Suzanne, see what results you get from the wet string/flex/flylead test. If no joy, try borrowing a set-top aerial as suggested by jb38 - I wouldn't buy one because set-top aerials will suffer problems of people walking round the room & outside, cars etc. but it'll give us an idea of how strong the signals are. AttenuatorS will be the way to go, but the values are yet to be guestimated.

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Briantist: No problem, thanks for the update, I'm just surprised you manage to keep up with everything.

Jonathan; Thanks for the update, as jb38 I look forward to the results of the testing.

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Richard: To be clear, it's not specifically a Mendip / Beckley "clash" as such, any more than digital transmissions from them and other Main transmitter sites have to "co-exist" with analogue (& digital) main & relay transmitter sites elsewhere.
Whilst you refer to community opinion, it's a shame that other options were not suggested at that time, that said if you wanted to get the best from the digital that was available, you would probably have t0o have gone down most of the route you did, but without getting rid of the analogue at that time.
However, we are now in a different ball game. With the increase in Transmission power, a lot of people will be using equipment whose sensitivity was more appropriate for the weaker pre-DSO signals and with High-gain aerials and boosters this equipment will be grossly overloaded leading to apparent loss of reception.

In this situation, the first thing do do is remove any booster from circuit. This is much more involved if it is a 'mast-head' amp as you will need to get up to the aerial to remove it (rememmber to remove the power unit first). However, if this is not a job you are able to do yourself, I would try an attenuator at the set end first - if a mast-head amp itself is not overloaded, then attenuation at the set will solve the problem.
If it's a simple booster in the loft or at the set, just take it out of circuit and join the two halves with appropriate connectors if required.

In virtually all cases, there will be no need to fit a smaller/lower gain aerial, fitting attenuator(s) will achieve the same and is considerably cheaper than an aerial rigger and aerial!

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Mike Dimmick: Richard's issue is that since DSO he now has so much signal he doesn't need his high gain aerial and booster (wasted money in his eyes) - the flylead hanging out the back of the set is providing sufficient signal although I suspect that it is picking up signal being radiated from the adjacent downlead or booster.

Whilst everyone who is suffering just the loss of one MUX should check for Single frequency interference because of the channel change that occurred, in most cases where people are close to the transmitter (as most of these recent posts are) it is gross overload, so it's removal of boosters and maybe additional attenuation that is required.

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