All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Gordon Elliott: One further thought.
If you build a filter on Veroboard and break the track so that one half is the unfiltered input and the other is the filtered output I wonder if the few millimetre gap would be sufficient or whether you would have to break it again and perhaps connect the bit in between to the screen.
I don't greatly understand RF and filters, just the basics.
And then there the question of whether impedance matching is important and however you achieve it....
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Lynn Steenson: The distribution unit does have a degree of amplification (+6dB). Cables, for example, have a degree of loss (i.e. minus so many dB, depending on type and length). The objective of an attenuator is to reduce the signal further.
Is this fed directly from the aerial or via a Sky box?
I've had another thought: I wonder if your receiver might not be built to receive the COM channels.
The COM channels use a different mode to the PSBs, and different to that which their equivalent multiplexes used before switchover.
The UK's standard definition networks and Ireland's Saorview network both use the DVB-T system (it standing for "Digital Video Broadcasting - Terrestrial").
However, there are a number of modes, which are sub-standards or parts of the DVB-T standard. The UK PSBs and UK COMs operate using a different mode.
If the receiver you are using is not Freeview approved then I wonder if it could be the case that it isn't designed to operate in the mode used for the COMs. The result could perhaps be that signal strength is registered but no quality, as is what you are getting.
I'm not a professional so am simply wondering whether such devices might exist. I know that some really old digital receivers were rendered useless at switchover because they weren't designed to comply with the DVB-T standard in full.
What's the make and model of the receiver you are using? It might be possible to find the specifications and work out whether this might be the cause.
Presumably you having a distribution amp means that you have more than one receiver. What do the others do?
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Lesley: Yes, removing the card to see what channels you get without it is OK. You can then insert it again and it should restore your subscription channels.
In such a case, I think that you will find that the BBC and ITV regions will change to their defaults (if your standard ones aren't the same). For example, they may become BBC London and ITV London. I've never used a Sky box but just going on what I've read.
The channels you would be left with on the Sky box would not be "Freeview" ones as that is the name of the terrestrial system in the UK.
The TV most likely has a Freeview receiver built-in for which you will need a terrestrial aerial (the dish is not suitable). Tuning the TV will not affect the Sky box.
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Liddy: On the signal strength screen it should also indicate which UHF/RF channel (frequency) it is tuned to.
I presume that your aerial is likely to be directed at Mendip and its ITV3 is on C48 (690.0MHz).
Ensure that it is not tuned to Stockland Hill on C25 (505.8MHz) or Wenvoe on C42 (642.2MHz).
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Liddy: There are different uses for the word "channel".
In the context of the number you select on your remote it is a "logical channel number" (LCN). That is, BBC One is on LCN 1 and ITV3 is on LCN 10, for example.
I was referring to the UHF (RF) channel number that ITV3 is being received on which is equivalent to the frequency.
Tune to ITV3 on LCN 10. Bring up the signal strength screen on which receivers usually say what UHF channel they are tuned to. This is sometimes given as a frequency in MHz instead, and I have given the equivalent frequencies for you, should this be the case with your receiver.
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Sally Ahmed: What you are describing could be as a result of the signal being too high. The effects of this appear the same as a signal that is not strong enough and/or not of sufficient quality due to the fact that the receiver gives false readings because its circuitry is being overwhelmed by signal.
Signal strengths vary a bit over time and it could be that it has relented a little. The trick is to ensure that natural variances in signal strength does not push it OTT.
Remove any booster and if there is no booster install some attenuation. I referred you to a page with some more information on this (see above).
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quitequick: Could it be the co-channel signal from Heathfield? If so, could you re-site the aerial where it picks up the interfering signal less?
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brian: You need to switch your TV to analogue mode and then tune it, with the Sky box powered on.
Or follow the method above to find out what RF channel your Sky box is putting its signal out on and then go to the TV and tune, in the analogue part, to that channel.
What is the make and model of the upstairs TV?
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Tuesday 22 January 2013 11:26AM
s brodie: No, you need to pay $ky for the privilege of using your own property (the box) and this includes viewing recorded content.