All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Eric Turner.: Well your reception of the COM7 HD multiplex which carries BBC News HD and others is obviously marginal. Maybe you would benefit from a replacement aerial or amplifier.
In an effort to restore COM7, try a manual tune of UHF channel 32.
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Daniel : I don't believe anything is planned, having looked at the relevant part of Ofcom's site:
Local TV Licensing | Ofcom
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Bob: Digital broadcasts are transmitted in multiplexes ("muxes"), each of which is a single signal which carries multiple services. E.g. PSB1 multiplex carries all BBC standard definition TV and radio. Digital UK publishes a full list of Freeview services including multiplex they are carried on here:
Digital UK Industry - Channel listings
As this is a reception issue, it's therefore more relevant to talk in terms of multiplex. So logical channel number (LCN) 64 is carried on COM6 (or Arq B) multiplex.
The PSB (Public Service Broadcaster) channels have the same coverage as the former four-channel analogues. COM4, COM5 and COM6 are available from 81 of the larger transmitters.
Rowridge is unique as far as a main station goes as it broadcasts with vertical polarisation (as well as horizontal polarisation). From April 2012 COM4, COM5 and COM6 began broadcasting with a power of 50kW horizontally and 200kW vertically. The PSBs are 200kW horizontally and vertically. Thus, you might find that vertical polarisation solves your problem.
DIY aerials tend to be widebands. All of Rowridge's channels are Group A, as they were for analogue. Thus, aerials installed for former four-channel analogue should generally be suitable for all reception of all channels. Wideband yagi aerials aren't as good on Group A channels so a Group A aerial should be used. See:
Rowridge Transmitter
While log periodics are usually wideband, to the best of my knowledge there's one exception; this one made by Vision:
V20A2 20 Element Log Periodic Group A Aerial ? Vision Products - Powerful Products. Easy Installation. Excellent Value
There's another point to be aware of and that is the new quasi-national HD muxes, COM7 and COM8. Rowridge carries these horizontally only and Whitehawk doesn't carry them at all. So if you can get them from Rowridge then switching to vertical polarisation will forfeit any chance of reliable reception of them.
Rowridge broadcasts BBC South and ITV Meridian (South Coast). Whitehawk carries BBC South East and ITV Meridian (South Coast). So choice of transmitter dictates BBC region but not ITV region.
The transmission power of Whitehawk effectively increased at switchover. The Findon relay had a considerable boost in power but only carries PSB channels, it being a relay of Rowridge.
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John Banks: The PSB (Public Service Broadcaster) channels are available from all transmitters and coverage is as the former four-channel analogue. The COM (Commercial) channels are available from 81 of the largest transmitters and coverage is not as good. In some cases viewers could get all the channels by using a different aerial, either on the same transmitter or a different full-service transmitter.
In other cases reception of the COMs may be variable, either because of the inferior signals and/or due to interference from another transmitter on the same frequency. This does not usually affect the PSBs as they have the better frequency allocations so as to ensure availability and therefore coverage.
The PSB channels carry the BBC, ITV, Channel 4, Channel 5 and some sister services of ITV and Channel 4. Sky News is carried on COM5 multiplex.
Digital UK publishes a full list of services by multiplex here:
Digital UK Industry - Channel listings
PSB1 = BBC A
PSB2 = D3&4
PSB3 = BBC B
COM4 = SDN
COM5 = Arq A
COM6 = Arq B
You've posted on the page for the Ramsey transmitter. As with all IoM transmitters, only PSB channels are available. As Google Street View doesn't have photos of the houses on Barrule Park, I cannot see where your aerial faces.
However, from Andreas Road I can see one property whose aerial faces Caldbeck. This is the only transmitter that is likely to provide you with all six multiplexes. The COM channels of Caldbeck are co-channel (same frequencies) as those of Divis, which is the main transmitter serving the eastern part of Northern Ireland. Therefore you could potentially find reception variable as and when Divis' signals carry.
As far as aerial type goes, the aerial used for four-channel analogue (usually Group A) is the same type required as now because all six multiplexes are in the same portion of the band as the former analogues.
So, if your aerial faces Ramsey (aerial vertical) then you should be looking to have a Caldbeck aerial installed instead.
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Bob: I should add that in order to understand Digital UK's list and its multiplexes:
PSB1 = BBC A
PSB2 = D3&4
PSB3 = BBC B
COM4 = SDN
COM5 = Arq A
COM6 = Arq B
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John Banks: My apologies. I have now located Barrule Park within Ramsey. With the postcode Google places it to the north of Ramsey.
This doesn't materially alter what I said. I cannot work out which is your house, but most aerials are pointing to Caldbeck rather than Ramsey.
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John Banks: My apologies, Ramsey is horizontally polarised rather than vertically polarised, as most PSB-only relays.
If your aerial points NNE then that suggests it does point to Caldbeck.
Caldbeck is on a bearing of 59 degrees. Ramsey, according to Digital UK, is on a bearing of 111 degrees at number 27. Obviously as it's so close, the exact bearing of Ramsey transmitter will vary by address.
A terrain plot suggests that the transmitter near to the Albert Tower might be out of sight, although obviously this may vary across the Park.
At digital switchover in 2009 Isle of Man transmitters all became part of the BBC One North West and the ITV Granada regions. Caldbeck broadcasts BBC One North East & Cumbria and ITV Border.
At switchover, Ramsey transmitter also had a considerable power increase. In the days of analogue it was on the top of Albert Tower, but now has its own structure, disguised as a tree:
mb21 - The Transmission Gallery
So if your aerial was installed prior to switchover then it may well have been directed to Caldbeck because Ramsey wasn't available due to the then low power (and it perhaps being out of sight). The move of transmitter might also help you, depending on where abouts you are.
The power increase might have changed things and may have been part of the change of regions for Isle of Man (i.e. so those relying on transmissions of another region from England now have the option of receiving BBC NW and ITV Granada -- the "new" IoM region). The downside is, as I've said previously, that Ramsey is a PSB-only transmitter.
There are two possibilities as far as your current set-up is concerned:
1. Your aerial points to Ramsey -- in which case it isn't pointing to the transmitter you are tuned to when watching the COM multiplexes (carrying Sky News and many others).
2. Your aerial points to Caldbeck -- in which case there is the question of whether there is something to be done that will improve reception of the COMs.
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Lauren : No. A "Freeview" box or TV will not work with a satellite dish (e.g. installed for Sky) -- it is "Freesat" that is the free-to-air satellite service and which will work with such a dish.
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Tuesday 23 June 2015 6:34PM
H Yates: Use manual tuning, if available. If not then it may be more tricky.