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All posts by Richard Davis

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


Simon: From what you say it does sound as if the signal is now too strong - the fact that in the interim period you had problems with the new MPX but not the old ones tends to point to this. As you've tried an attenuator in your set's aerial lead without success it sounds as if the distribution amplifier for the block may be overloading, which means that the attenuator needs to go in that amplifier's input. I wouldn't put too much faith in what the managing agents say!

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Simon: I must admit I was a little surprised that some of your neighbours aren't having problems, but I think Dave Lindsay has probably hit the nail on the head - they're probably using satellite or cable. If you can confirm that all those who're using the aerial system are having problems, you might between you be able to force the Managing Agents to take some action.

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Simon: Glad to hear that you've made progress with your problem. Don't worry about the 4kW of digital (or a total of 24kW if you add all the six multiplexes together)- the old analogue service had four channels of 10kW plus one of 5kW (Ch 5), giving a total of 45kW, so you're being subjected to less RF energy now than you were before!

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Hi, Brian -
One thing in this post isn't clear. You say "The Children's and News channel numbers will move on the Wednesday that follows 16 weeks after LCN 65 is allocated" - when does this mean? Does it mean that the date hasn't yet been decided, and if so when will we know?

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Although it's the end of Nicam 728, which was the version of Nicam used to carry stereo audio to the TV veiwer, Nicam was originally developed to carry audio within the BBC and I suspect that this earlier version, which has slightly different paramerets, may still be in use in some places for some time to come, fo example feeding some FM radio sites. Outside the BBC, I know that Classic FM used to use a version of Nicam to feed their FM transmitters, and It wouldn't surprise me if they still did.

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A further comment - I'm afraid your statement that "most equipment was unable to record them (so they did not get recorded onto domestic video tape) or produce them" is not true! From the start of the Nicam era (1989 in the Brighton area, if I remember rightly) until I went digital about two years ago, I used a succession of VCRs and later a VCR/DVD combibation recorder as stereo TV tuners feeding my hi-fi along with a mono TV. Not only did they all produce stereo audio out, they also recorded it, both onto video cassette and DVD!

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Hi, Brian -

I'm a little insulted that you reckon I can't tell the difference between mono and stereo! :-) As a retired BBC engineer and amateur sound recordist, I don't think I have cloth ears to that extent! As other correspondents have confirmed, NICAM video recorders right from the start of the service uesd to output stereo sound on the left and right legs of the Scart - this was how I uesd to get it, as my fist NICAM VCRs didn't have any other audio outputs - and they could also record it onto the video cassette Hi-Fi audio tracks, and indeed later onto DVD. If you don't believe me, you're welcome to come round to hear some of my old recordings made from analogue TV in that way - I think you, like me, live in Brighton!

No hard feelings!

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Like you, Arnie, I've seen many properties in Brighton and Hove with new horizontally polarised aerials pointing at Whitehawk! It just goes to show how incompetent/ignorant some TV aerial companies are! Many of these aerials are on council-owned properties, and will have been put up as part of the council's programme of replacing all the communal aerial systems in time for DSO - the council have presumably contracted this out to various firms, some of whom are more competent than others. In the case of DIY-types who've replaced their own aerials, I suspect it may have to do with the fact that Britain is almost unique in using vertical polarisation, most countries on the continent using only horizontal. Because of this, the instruction leaflets supplied with continental-made aerials may not mention any way of mounting other than horizontal, and someone who knows nothing about aerials and is just following the insructions will thus mount the aerial horizontal, as no doubt the diagrams will show!

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One reason that Whitehawk Hill is vertically polarised is that it was originally classed as a relay transmitter rather than a main station, as during the analogue days it relayed transmissions received from Rowridge. It only changed to being considered as a main station when everything went digital, since it now has its own dedicated programme feeds rather than relaying another station.

As regards receiving aerial polarisation, using the incorrect one can lose you about 20dB in signal - that's equivalent to reducing the transmitter power by a factor of 100, and more than cancelling out the gain of your aerial, which is unlikely to be as high as 20dB! Further, you may get increased problems with reflection, since the polarisation of the signal can change when it's reflected, causing the reflections to be stronger than the wanted signal!

To show how effective using the wrong polarisation is in attenuating the signal, you only need to consider that this is deliberatly done with satellite transmissions to allow two different multiplexes to to transmit from the same satellite on the same frequency without causing each other interference. A change in the operating voltage sent to your LNB from your digibox is used to switch the LNB to the correct polarisation for the service you want.

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I suspect the shopping channels pay Freeview a handsome amount to transmit them, so even if hardly anyone watches them they're a valable source of income to Freeview and so are likely to stay, as no doubt are the various "adult" channels! In effect, these services are subsidising the ones that most of us actually watch.

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