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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Paul Weaver wrote: > On Sat, Jul 08, 2006 at 12:43:01PM +0100, Rob Beard wrote: > >>Thats what I thought. It works ok with out Freeview box although we >>can't get Channel 5. The ariel is not a proper digital ariel so I guess >>that doesn't help. > > > There's no such thing. > > Digital and Analog TV are broadcast on the UHF spectrum, in 8MHz > channels, from channel "21" to "68" inclusive. BBC1 Analog might be on > 24, ITV on 27, for example. BBC Mux 1 might be on channel 41, Mux B (the > second BBC one) on 22, etc. etc. The reason it's so spread out is due to > interference with neighbouring regions (and countries). Typically the spacing is 3-3-4 because the channel bandwidth is greater that the channel spacing (WLAN has the same issue.) > Normally channels aren't broadcast next to each other, although > ocassionally Digital will be interleaved with Analog. > > If you get Five on analog, chances are it's arround channel 36, there > were problems when it launched as many VCR's used UHF36 to output their > signal. To add complications, many people get "Five" from a different > transmitter to normal TV. In addition main transmitters generally use horizontal polarisation and relay stations generally use vertical. Unless you are lucky "different transmitter" is likely to equate to "different aerial". > > Nethertheless, most areas of the country has analog TV clustered in the > same portion of the UHF spectrum. Channel 21 - 36 for example. This > means many aeriels are in certain "groups", which provide high > gain/pound for certain UHF channels. There is a list of the groupings on http://www.bbc.co.uk/reception/analogue_tv/anatv_aerials.shtml > > When digital started, it wasn't always possible to broadcast the 6 DTT > channels in this range. As such, while your aerial might get a great > picture for BBC1 on UHF23, it might not for Mux A on UHF56. Only a group W will pick up both channels, whereas a group A or K would pick up channel 23 fine. Stockland Hill has 22: 479.25MHz MUX 1 23: 487.25MHz ITV1 25: 503.25MHz MUX A 26: 511.25MHz BBC2 28: 527.25MHz MUX 2 29: 535.25MHz CH4 30: 543.25MHz MUX C 32: 559.25MHz MUX B 33: 567.25MHz BBC1 34: 575.25MHz MUX D On 01/05/09 MUX 1 moves to channel 26 On 30/05/09 MUX 2 moves to channel 23 and MUX A moves to channel 29 > A "digital" aeriel is a wideband aeriel, which gives a good gain > across the UHF spectrum. They may sometimes give a lower gain on some > channels than a "Grouped" aerial. No doubt there are quite a few places putting "digital" stickers on group W aeriels and selling them at a hefty markup :) > > The fact you can pick up two MUXes fine, but not the rest, leads me to > believe that your local transmitter broadcasts something like > > BBC1 UHF56 > MUX1 UHF57 > BBC2 UHF58 > ITV UHF62 > C4 UHF60 > MUXB (BBC) UHF62 > > MUX2 UHF28 > MUXA UHF30 > MUXC UHF34 > MUXD UHF40 Assuming they have a group C/D aerial. With a group E aerial they'd have problems with MUX2, MUXA & MUXC. But could get MUXD and channel 5. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFEtAX9soRLMhsZpFcRAgv/AJ44PLAxKzqmGhUR6qO0vDONNurfqQCfeipK Ny9p2A3EXryEg4n9Cphl4Z8= =quSX -----END PGP SIGNATURE----- -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/linux_adm/list-faq.html