All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Chris Burmajster: It is right that Marlow Bottom transmitter will not provide the full range of Freeview channels as it will only carry Public Service Broadcaster (PSB) channels.
The Commercial broadcasters (the "COMs") transmit from 80 of the largest (by viewer population) stations and achieve a 90% reach. For them to transmit from nearly 1,100 relays like Marlow Bottom would roughly double their cost of transmission. If they did this, that outlay would give them an additional 8.5% of the population. They were invited to increase their coverage and declined. For a more in-depth explanation, see Will there ever be more services on the Freeview Light transmitters? | ukfree.tv - independent free digital TV advice
In some cases there are ways of getting the Commercial channels. These usually entail additional cost as new aerials will be required.
I had a look and have come up with the following shortlist of permutations. Not all may be possible as what can be received can only really be determined by an installer on site.
I went to the Digital UK (DUK) Tradeview predictor and put in post code in Marlow Bottom. This was to give an idea of what may be receivable.
1. Receive all services from Crystal Palace. At the test post code, DUK suggests PSBs are "good" but COMs "variable". The point being that there is a difference and the COMs aren't as good.
As Marlow Bottom is a relay of Crystal Palace, regional programming is the same.
2. The predictor considers all services (PSBs and COMs) from Hannington to be "good" at the test location. One option is to receive all services from Hannington, but this would mean changing to BBC South and ITV Meridian.
3. Use Freesat in combination with a terrestrial aerial on Hannington. You can watch BBC and ITV London programming via Freesat. Your Hannington aerial will allow you to watch terrestrial Commercial services that are not on Freesat such as Dave and Pick TV.
4. You may be able to combine ("diplex") into one downlead, your current aerial on Marlow Bottom with one on Hannington. In order to do this a diplexer must be used so that only one of the aerials supplies the signal on each channel. See here Online TV Splitters, Amps & Diplexers sales
Marlow Bottom uses C49 to C58 and Hannington's highest COM is on C47. So you would need a diplexer that splits at C48 (if such a thing is available - I'm not an aerial installer so I don't know).
This is probably a last ditch possibility where all others have been eliminated.
I should point out that some receivers (recorders/PVRs) don't function well when receiving services from different transmitters with regards to recording programmed programmes. You could use your Hannington aerial as your main one, so the services from that transmitter will be in the "proper" logical channel numbers, i.e. 1=BBC One from Hannington 2=BBC Two from Hannington. The only use your Marlow Bottom aerial will have is for BBC One London and ITV London which you could put on 800 and 801, for example.
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As I say, what's actually possible will have to be tested on-site. The village is surrounded by trees and these can affect reception. They will probably not be taken into account by the DUK predictor.
At the test location, the road is not flat and the houses on one side are higher than on the other. It's a fair assumption that chances of reception are likely to be greater the higher up the aerial is. The size of aerials and tall masts tells the story!
I did spot a couple of houses on the low side of the road with large aerials on Crystal Palace. These are in the direction of the other side of the road, so the higher houses will probably be causing a shadow. However, what I would say is that if those lower houses can get a signal from CP, then the chance will probably be greater if you live in one of those higher houses!
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m kinsella: I would second David's suggestion!
It should sort itself out then. In the mean time, switch to analogue to watch BBC and ITV regional programmes.
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Chris Baldwin: Try tuning to Dover's analogue services which are 50, 56, 66 and 53.
It does depend on whether there are any French transmitters that are co-channel that may interfere at your location.
The green coverage area above suggests that along the French coast it may be possible to pick it up.
Due to the fact that the powers that be will not release the radition patterns of Dover's post-DSO multiplexes, the above is an assumption.
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tim welby: I believe that the above is not entirely correct.
The Digital UK Tradeview predictor says that the positive offset is on PSB3 (i.e. C39+) and not PSB2. Furthermore, COM4 does not have a positive offset either. Briantist, you might like to look at this.
The Ofcom document, apparently updated January 2012, also says that Hannington's channels are not offset except PSB3:
http://stakeholders.ofcom….pdf
Also, COM5 is on its full DSO power of 25kW. COM4 and COM6 remain on low power until 18th April when the Guildford transmitter relinquishes use of these channels.
Tim, before I started, having simply looked at the channels at the top of this page, I was going to suggest that your problem may be that your receiver can't cope with the positive offset employed by PSB2, but I don't believe that this is the case.
I have been reading through your earlier postings that you made since switchover. You seem to have been having alot of issues since switchover.
As Mike Dimmick explained ( Freeview on Hannington TV transmitter | ukfree.tv - independent free digital TV advice ) the difference between pre-switchover signal strength and post-switchover strength in your direction is huge. You may have had an aerial installed that was sensitive enough to pick up the pre-DSO signals, but which is now drawing in too much signal and overloading your tuner.
The reason for the marked difference is due to the fact that pre-DSO signals were considerably weaker in the general direction of Guildford (the "Guildford notch") in which you reside. This was so as to protect those using Guildford transmitter against interference as the two shared channels. So you have gone from having low low low signals to high ones.
Have you tried fitting an attenuator?
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Lynne Sayers: Can you give some more information such as location as it is impossible to be very specific. Is the aerial used for the bedroom the same as used for (I presume) the lounge?
What I will say is that if your neighbour is served by any of the London transmitters, then this will likely right itself on Wednesday.
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kim stevens: Switchover at all transmitters is carried out in two stages, usually two weeks apart.
At the first stage BBC standard definition services go on to full power and two weeks later the rest follow.
So if you're receiving from High Wycombe transmitter, independant channels will become available to you on Wednesday.
By the way, if you do receive your TV from High Wycombe, then you won't get the full Freeview service as it's a Public Service transmitter only.
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markyb: Cables can interfere with one another when in close proximity. The lower the level of signal the greater chance that any interference will have a negative impact on reception.
So come switchover when the signal levels from Heathfield are higher, you may find that such interference does not result in loss or poor TV reception.
I have a USB dongle TV tuner and I know that if the RF aerial cable is put next to the USB lead then it causes problems with reception. that is, the signal carried along the USB lead interferes with that in the RF lead.
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Marion Bristow: It is difficult to be specific only knowing that you live near Bedford. However, it is quite close to the transmitter and your could therefore be in a situation where the aerial is picking up too much signal and overloading the tuner. As signal levels vary over time due to atmospherics, perhaps at times it gets too high for your receiver to cope with.
Unless the channels stored in your receiver's memory are incorrect, then retuning is a waste of time and can only ever leave you without the channels being stored in the memory or with the channels stored in the memory as they were before you retuned. Therefore the affect can only ever be negative or neutral and not positive.
Have a look at this page:
Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice
If you have a signal booster, then remove it. If not, then try fitting an attenuator to reduce the signal levels.
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Ben Ward: It's possible that other leads are interfering with the signal carried along the aerial lead. Notably HDMI and USB leads
If they are in close proximity, try moving them away from one another and see if the signal improves.
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Saturday 14 April 2012 1:49PM
John Stone: Rouncefall is not a full service transmitter as it only carried Public Service channels. I see that Sudbury and Rouncefall are only 14 degrees apart from your location and of course Rouncefall broadcasts on the same channels as Sudbury.