All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Richard Hawkins: Perhaps it could be too much signal being fed into your receiver.
Tunbridge Wells and Heathfield are a "Single Frequency Network" (SFN) which means that they transmit on the same channels. This is perfectly OK as the digital system allows it.
Heathfield is horizontally polarised and Tunbridge Wells is vertically polarised, but your aerial could still be picking up Heathfield to a degree. What you get down your aerial lead is the sum of what's been picked up of the two signals.
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Keith: 626MHz is C40 which is from Sutton Coldfield.
What I suggest you do is run the automatic tuning scan and unplug the aerial when it gets to 30%. This will have the aerial in for Ridge Hill and unplugged for all of Sutton Coldfield's channels.
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Tony: This is the two-tier terrestrial television transmitter network we now have, I'm afraid.
Newhaven only carries the Public Service Broadcaster (PSB) multiplexes (groups of services).
Those that it doesn't broadcast are the Commercial (COM) multiplexes and these carry the likes of ITV3, Pick TV, Yesterday, Film 4 and Dave.
The COMs broadcast from 81 of the largest transmitters (largest by viewer population) and cover about 90% of the population. The other 1,000 or so relays, including Newhaven, are PSB-only. The cost to the COMs of including the relays in their portfolio would roughly double their cost of transmission whilst only adding about 8.5% of the population to their potential viewer-base.
As they are run entirely as profit-making ventures and have no "Public Service" obligation, they decided to turn down the offer of additional coverage.
In some cases reception of COMs can be achieved from a station that carries them. Obviously this requires a new aerial and in some cases due to poor signal, a big aerial and sometimes big mast.
Failing that, the main option to get more channels is Freesat. There are some channels like Yesterday and Dave that are on full Freeview (COM) but not Freesat.
I'm sorry it's not what you were hoping for. It's a common question and I believe that "Freeview Lite" has got to be the biggest let-down, particularly as mention of this inferior service doesn't feature in any of advertising. "Subject to coverage" fails to make clear that not all channels are available in all areas.
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Mazbar: Follow the link to DUK Tradeview or hover your mouse over the links on the right of Tracy's posting to see her post code displayed in the status bar at the bottom of your screen.
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Tom: The problems are in receiving the Commercial (COM) channels. These have limited coverage with respect to the Public Service Broadcaster (PSB) channels.
If you received four-channel analogue before, then you should get at least the PSBs now.
See here for a list (those with bullets in the "E"/England column apply):
DMOL Post-DSO Multiplex Channel Allocations
The PSBs therefore have BBC, ITV1, ITV1+1, Channel 4, Channel 4+1 and Channel 5, among others.
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Tom: It mainly depends on which transmitter that you are receiving from as to what you'll get:
- Heathfield | aerial horizontal - Broadcasts PSBs and COMs. COM4 (ITV3 etc) is on low power until 27th June on which date there is a retune for it. You might not get it until then.
- Hastings | aerial vertical - The COMs from Hastings use the same three frequencies as the PSBs from Eastbourne South Tower, so you may find them drowned out, or at least hit and miss, thanks to the interference.
- Eastbourne (South Tower) and Eastbourne Old Town (Jevington House, Upperton Road) | aerial vertical - These are PSB-only transmitters.
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Neil: The transmitters that serve your area have all switched to digital and all services are as they will stay.
To work out why you might not be getting ITV4, knowledge of which transmitter you are using may help.
First off though, see this page which lists all Freeview services (those with a bullet in the "E"/England column apply):
DMOL Post-DSO Multiplex Channel Allocations
There are six multiplexes (groups) of services. ITV4 is carried on COM6. Are you missing COM4 and COM5?
Looking around on Streetview, there is a mix of Reigate and Crystal Palace. Both are in the same direction to a few degrees, but it is easy to identify which is which when you know how:
- If you are on Reigate then your aerial will be vertical (elements up/down). For Reigate you will probably need a wideband aerial to receive the three COM multiplexes. If you don't have a wideband aerial, this may cause poor or non-existant COM reception.
- If you are on Crystal Palace then your aerial will be horizontal (elements flat). For Crystal Palace a wideband aerial is not necessary and all channels should be receiveable using an aerial used for the former four-channel analogue.
The only thing to be aware of about Crystal Palace is that COM6 has a negative offset and other channels do not. There is a known issue with some devices which cannot receive the type of signals used after switchover (those in 8k mode) that have a negative offset. I won't explain what the negative offset issue is unless it turns out that you have an affected device.
If you are on Crystal Palace and find that you have COM4 and COM5 but not COM6, then post your make and model number and I will see if I can find out if it is a model that has the negative offset issue.
If you are on Reigate, then the negative offset problem cannot be an issue as Reigate's COM6 does not have a negative offset.
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Neil: I should point out that Reigate and Crystal Palace are nearly north east.
The predictor suggests that Midhurst and Heathfield could be possible and these are south west and east south east respectively. For both, aerials are horizontal.
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Owain: There should be no aerial upgrade required to receive Freeview HD.
Have you tried to receive it?
If so, what's the make and model of your TV or box?
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Sunday 17 June 2012 12:28AM
Declan: What is sufficient depends on the location. Loft aerials get less signal due to it having to pass through the roof. Some roof slate isn't particularly conducive to a loft aerial.
See this plot which would suggest that you may have good line of sight at 14.5 miles:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
Obviously this doesn't take local obstructions into account, which is why I say "may have". If you're in a house, then that's obviously better because the aerial is higher up than a bungalow. If you're in a bungalow, then it might be best to mount it on a pole so that it's above the roof line.
You may be able to conduct some tests in your loft with your former roof aerial, if it is still in one piece.
See ATV Sheffield's website for lots of information and an online shop www.aerialsandtv.com
See:
Aerials, TV Aerial and Digital Aerial
It does hinge on how much your roof will attenuate the signal, but it does look like a log might work in your location.