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Brian Butterworth published on UK Free TV For the last six years, I have answered many thousands of personal emails that you have sent to UK Free TV.
Sadly, I am unable to offer this personal service at the moment.
Until I can restore this service, please can you leave any questions you have on an appropriate page, where they will be answered as soon as possible, or below, if you can't figure out where to ask.
I look forward to your questions!
Help with TV/radio stations?
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Wednesday, 30 March 2011
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david6:37 PM
ihave sky in one room and i have a labgear box in another what i want to know is will a sky card fit this or do you need a different one if so could you let me know which one thank you
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Thursday, 31 March 2011
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Norman Strath1:44 PM
Turriff
I had a freeview arial with a masthead amp and got nearly all the channels but the signal would drop out I have installed a new 91 element aerial wideband and come off the Durris transmitter which I am sytill having problems my aerial is 90 degrees to where the transmitter lies and there is a big scots pine between me and the transmitter is this the issue.
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Mike Dimmick6:09 PM
Reading
Norman Strath: The aerial has to point nearly due south to pick up Durris properly. The tree won't help - is there another place on the building that you could mount the aerial that would avoid the tree?
The aerial could be pointing west, towards the Knock More transmitter, but you're expected to get better results from Durris. In fact there's no prediction for Knock More - there are three mountains between you and it.
The commercial multiplexes are still broadcasting at low power, and you aren't expected to get a usable service from them until the 15th of June.
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Penny7:02 PM
York
Neil, hello again! I am so sorry I didn't get to the bottom of this for you...I have a wall socke which says "return" "tv" and fm dab". In the "tv" one I have a splitter - a thing that is roughly Y spaed which pugs into the tv socket and has two outlets for aerials. In one socket goes the aerial for the sitting room. In the other one goes an aerial wire the other end of which goes into "return". THAT goes through to the bedroom socket (through the magic of whatever is already wired in the walls!) and makes the bedroom socket work. The "loop" is just the length of aerial wire which can be as long as you like or as short as will reach from "tv" to "return". Obviously all the male/female ends have to marry up. I do hope this helps you.
Penny
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Friday, 1 April 2011
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Bill Martin2:20 PM
Crowborough
I understand that TV signal transmitter power will be much less than currently used for analogue. Has anyone calculated the saving in electrical power that the nation will enjoy following DSO which is to be completed in 2012?
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Mike Dimmick3:14 PM
Bill Martin: Ofcom published some research here:
Ofcom | Cost and Power Consumption Implications of Digital Switchover
That's the increase in domestic power consumption.
It's harder to give an accurate assessment of transmitter power consumption. The quoted figure of max ERP for analogue is the sync peak. There is a period of unmodulated* carrier on every line as the legacy CRT scan beam moves from the end of one line to the start of the next. There is also a longer period at the end of every field as the beam returns from the bottom of the screen to the top. (A frame, one picture, consists of two interlaced fields.) These periods are generally called 'sync' or 'blanking interval'.
* OK - the carrier is now modulated to carry Teletext, Programme Delivery Control and other data in the Vertical Blanking Interval. But the modulation is very small.
The sync pulses are 42% larger *in voltage* than the peak level during the visible part of the picture. That makes them over twice as large in power. The peak level is only seen for a completely black picture - the brighter the picture, the lower the transmitted level. Yes, seems weird, but we used to use 'positive' modulation, where white gave larger values than black, for 405 line VHF TV and there were often reception problems, so we used negative modulation for UHF. A medium-brightness picture might be only be 35% of sync peak in voltage, making sync peak about 8 times the power of the picture information. That's about 9 decibels.
You can see the difference at Wright's Aerials . There are massive narrow spikes at C37, C41, C44, C47 and C52, somewhat towards the left of the centre of the channel. Those are 870kW max ERP. The adjacent digital multiplexes at C40, C43 and C46 have roughly the same level as the actual picture content of the analogue transmissions, but are quoted as 10kW max ERP.
After switchover Emley Moor's digital multiplexes will run at 174kW max ERP. That will actually make the digital signals larger than the average level of the analogue signals.
Bill Wright did actually make some measurements from Emley Moor when it was transmitting test signals a couple of weeks ago, but I don't have the links to hand.
The transmitter equipment at most sites is all-new, and the aerials have largely been replaced with more efficient designs, so there may be some savings from that route. However, there's a chance that the actual electrical power used will actually be greater, not less - the main sites will now transmit six high-power muxes rather than four or five analogue signals, although relays will transmit three muxes rather than four analogue channels, and of course the six low-power muxes at the main sites are switched off.
(ERP = Effective Radiated Power. The actual power emitted by the transmitter, multiplied by the transmitting aerial gain at that frequency, compared to an isotropic radiator.) (RG47SH)
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Mike Dimmick3:16 PM
Reading
Incidentally Arqiva have recently submitted planning applications to install solar panels and batteries at some sites, to reduce the grid power required and possibly sell some power back to the grid. Most of their sites are in the open and with few surrounding buildings, and are already an eyesore so adding solar panels isn't going to make it worse!
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Mike Dimmick3:27 PM
Reading
Penny: it sounds like your house was wired for Sky 'magic eye'. The cable has to be a continuous run from one box to the next so that the RF output from the Sky box is sent to all boxes, and the signal from the 'magic eye' box at each location gets back to the Sky box.
Otherwise, it's not normal to wire up a building like this - normally you split the aerial cable as close to the aerial as possible so the signal at each point isn't harmed by the noise generated in each box. Obviously in an apartment block you don't want each tenant's 'magic eye' interfering with each other - you don't want your box to change channel when your neighbour uses his remote!
Neil's problem is likely to be one for the building management company or landlord, to ensure that the signal levels are adequate at every provided aerial point. Unless, of course, they only originally fitted the main point in the lounge and the bedroom is different.
Neil: If the socket that doesn't work has a screw thread on it, rather than just a plain sleeve, that's probably a satellite point rather than an aerial point. It's amazing that it works at all, but you're so close to the Sutton Coldfield transmitter (11km) that there is a good chance of picking up a detectable signal just in the cable or TV, with no aerial connected to it!
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Mike Dimmick3:31 PM
Reading
Penny: a further thought - the wiring was probably intended for a Sky box, where you would plug the aerial lead from the socket marked 'TV' to 'aerial IN' on the box, and another lead from 'aerial OUT' to the 'return' socket. You need a 'Y' splitter because the TV doesn't *have* an 'aerial OUT' socket - it's not designed to chain up to another device or add its own output to the cable.
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