All posts by Steve Donaldson
Below are all of Steve Donaldson's postings, with the most recent are at the bottom of the page.
Mrs C Liston: Having looked into this further, it looks like high ground at Crowborough isn't completely obstructing the view to the transmitter, although it is still high enough to potentially cause an issue. The terrain plotter I am using had the height of the Heathfield mast down as being not as tall as it is. Having consulted another source to find the correct height, I have now entered it into the terrain plotter, taking a couple of sample locations in Oxted and it seems that the top of the mast can just about be seen, although the terrain is still a little in the way.
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Pete Howell: That's good to hear. It was quite in-depth, I know. So long as you have done the tuning and know what to do should it need doing again, that's the main thing.
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Graham : In addition to that said by StevensOnln1, if the manual tuning screen offers a choice of DVB-T or DVB-T2 then the latter must be selected for C41, PSB3, the HD multiplex.
The other five main multiplexes and the local multiplex on C39 (if you can get it) are DVB-T.
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Jon Henderson: Sky News is carried on COM5 / Arq A multiplex, which means all programme channels on the multiplex will have the same issue. The full list of Freeview programme channels is here:
Channel listings for Industry Professionals | Freeview
Is your aerial horizontal, meaning elements flat? Or is it vertical, meaning elements up/down (just as they are for aerials facing eastwards towards Whitehawk Hill next to Brighton Racecourse)?
As per my reply to Craig William simm immediately prior to yours: use vertical polarity. Since digital switchover in 2012 Rowridge has been transmitting with both horizontal polarity (HP) and vertical polarity (VP) for the six main Freeview multiplex channels.
Craig is near Southampton and in that area there is an additional multiplex which is HP only. This doesn't apply in the Worthing area. In Worthing you receive only the six main multiplexes, and all are HP and VP, with the COM channels (which includes Sky News) having lower power for HP.
Also explained in the reply, Mont Pincon is a high power transmitter about 25 miles south west of Caen, and it broadcasts on the same three UHF channels of Rowridge for its COM channels (the ones that are lower power HP).
Mont Pincon is 127 miles or so from Worthing, a little clockwise of south. It broadcasts HP only, hence using VP helps with rejection of the unwanted signals, when they come in stronger. The benefit is therefore two-fold: increase the level of the wanted Rowridge signals (picked up by your aerial) and decrease the level of the unwanted signals from distant transmitters which are HP.
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Jon Henderson: In terms of retuning, it's a total and utter waste of time. Unless the tuning is incorrect, as in the TV is tuned to another transmitter, then don't do it for a reception issue.
If the TV is tuned correctly, then this means it has stored in its memory the channels of the designated transmitter. If the picture breaks up or disappears completely, then that is an issue with the signal from the transmitter not getting to your aerial and coming down the aerial lead into the TV. Retuning will not have any effect whatsoever on such an issue!
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Jon Henderson: In which case then, could it be tidal? A good proportion of the signal path is over water. The further east you are, the sooner the line leaves land before reaching Manhood Peninsula and the further out to sea it is.
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Jon Henderson: The question of tidal is to mean: does the issue coincide with a particular tide level? For example, when it happens, is it always high tide? And when it is low tide does it not happen, or usually not happen?
With analogue broadcasts, each programme channel, e.g. BBC One, BBC Two etc., was carried on a separate broadcast signal. Hence, for the four main channels you had four signals. With digital, multiple programme channels are carried by a single signal known as a multiplex. It isn't the case that you can have bad reception on one programme channel on one multiplex, but not the other programme channels carried on that multiplex. Bad reception found on one programme channel of a particular multiplex will be found on them all, because the receiving part of the TV is receiving exactly the same signal.
There are six Freeview multiplexes. On the Freeview link I gave you, they are identified by name in the "Mux" column of the table. Here are the designations for the six multiplexes:
PSB1 - 'BBC A' - carries BBC standard definition TV and radio
PSB2 - 'D3&4' - carries ITV, Channel 4, Channel 5 and some of their sister channels
PSB3 - 'BBC B' - carries all the Freeview HD channels, both the BBC ones and the non-BBC ones
COM4 - 'SDN' - carries QVC, Drama, 5USA and others
COM5 - 'Arq A' - carries Sky Mix, Really, Dave, Sky News and others
COM6 - 'Arq B' - carries Quest, Yesterday, GREAT! movies and others
The reason for including this list of multiplex designations is because it's easier to refer to them as 'PSB1' or 'COM4', or 'the PSBs', rather than names such as 'BBC A' and 'SDN'. The Freeview list of channels lists them by name; you can now relate these to the PSB/COM designations which I will speak of.
In terms of the lower power multiplexes from Rowridge, it is the HP COMs that are lower (at 50kW) only. The PSBs are 200kW HP and VP. The COMs are 200kW VP. Hence, turning the aerial vertical takes advantage of the 200kW COMs.
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Jon Henderson: The way in which you opened by saying you are in Worthing 'but' use Rowridge in order to get BBC South sounds like you can receive from Whitehawk Hill and perhaps that you used to, and changed to Rowridge at digital switchover when you found out Whitehawk had been reattributed to BBC South East.
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Jon Henderson: It's worth outlining the situation with regards TV reception in the Worthing area. At digital switchover (DSO) in 2012 Whitehawk Hill changed from being a BBC South transmitter to being BBC South East. I seem to recall that the editorial regions of the news programmes changed accordingly.
Also at DSO, the Findon transmitter, which sits north of High Salvington, on West Hill, had a big increase in power (from 50W to 2,000W) and new transmission antennas, including to the south west, a direction it didn't broadcast for analogue. I believe this was done as a measure to give back some coverage to BBC South, Whitehawk having been reatrributed to another region.
Findon, like many relays, carries only the PSB channels, so no COMs, those you are having difficulty with from Rowridge. On its own, it is therefore unattractive to those who can receive the full service, even if it isn't easy. Those up the valley in Findon village, say, have no other option and can only receive the PSBs from Findon transmitter. I do wonder how well used it is in Worthing, as in how much uptake there has been in the extended coverage area as a result of the power increase and new antennas.
In 2019 the top part of the TV band of frequencies was cleared for mobile use by changing some of the channels used by some transmitters. While Findon and Rowridge didn't change, Whitehawk did. Findon's PSBs are 41, 44 and 47, and Whitehawk's COMs are 32, 33 and 34. These allocations lend themselves to being combined into one cable feed with a diplexer, thereby allowing reception of PSBs from Findon (with BBC South) and the COMs from Whitehawk (which Findon doesn't broadcast). This is the alternative to attempting to receive all channels (PSBs+COMs) with BBC South from Rowridge.
I think Findon may cover Worthing pretty well. I tried postcodes for Goring Road where the shops are, near to where it changes to Mill Road, the college and Lancing. It's generally flat so I imagine that Findon is available to much of the town.
For people on Whitehawk who want BBC South instead, rather than changing to Rowridge with the potential for variable reception, particularly of the COMs, they could add another aerial for Findon.
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Monday 18 December 2023 3:03PM
Mrs C Liston: Heathfield was listed for engineering works last week, although it is not now. This is not to say that it hasn't over-run and not shown on the Freeview webpage listing engineering works here:
Planned engineering works | Freeview
You've asked a few questions and therefore I will address them in turn.
In regards retuning, the answer is "don't do it!". By resetting you have cleared the tuning for the designated transmitter. Having done that, retuning will only ever pick up what was tuned before, if at all. Crucially, it can't make a signal reappear that has disappeared!
The point is that the issue isn't with the tuning, but that the signal from the transmitter isn't coming down the aerial lead into your TV. If the TV is tuned correctly, meaning tuned to the channels of Heathfield, then it will show a picture when fed with the signal from Heathfield.
That you are in Oxted with your aerial pointing to Heathfield means your aerial is pointed towards France. In regards the TV tuning in French channels, it may or may not be that these are on the same UHF channel (frequency) as Heathfield. It is possible that they are not and that by deleting the Heathfield tuning, your TV has chosen the French channels because they are the best signal it can find across the whole TV frequency band (because Heathfield is absent at the time you retuned).
In effort to restore your channels (and so you have TV for Christmas), use manual tuning to select the broadcast channels of Heathfield:
PSB1 - BBC One - C41
PSB2 - ITV - C44
PSB3 - BBC One HD - C47
COM4 - QVC - C40
COM5 - Sky Mix - C43
COM6 - Quest - C46
To explain the above, one digital transmission signal carries multiple programme channels, and this is known as a multiplex or "mux". So all the BBC standard definition TV and radio channels are carried on PSB1 multiplex, which is broadcast on UHF channel 41 (C41) from Heathfield. In the above list, I have given one service on each multiplex. Check you are tuned to the appropriate UHF channel for that multiplex from Heathfield. Crystal Palace channels to look out for, in the same order, are 23, 26, 30, 25, 22 and 28.
With regards satellite TV, then there is Freesat and this is the satellite equivalent of Freeview. Some of the channels available are different. The point is that in order to have satellite TV you don't have to subscribe to Sky. The dish for Freesat is exactly the same as for Sky. I appreciate you said you don't want a satellite dish, but I thought I'd let you know this, should you be faced with no other option.
In terms of distance, then the bigger factor with TV reception is being able to see the transmitter. Some people are close to a high power transmitter but can't receive because there is a hill in the way. That said, Oxted is quite a distance from Heathfield and there is high ground in the way around 16 miles out around Crowborough.
Reception across a town will vary, therefore it's not possible to assess or give any idea of whether it may be possible to receive Crystal Palace at your location. A full postcode is required.
Not being familiar with the area, I can see that Oxted has high ground to the north, thereby making Crystal Palace difficult or impossible. With Heathfield, you have High Weald blocking your line of sight, in the Crowborough area around 16 miles out. Depending on whereabouts you are, there may be ground in the immediate vicinity in the way too.
If your aerial is pointed to Heathfield, then the decision may have been made that this was the better (least worst) of the two. But, as I say, neither is ideal because high ground is in the way for both. Or it could be that it is "much of a muchness" and that you might benefit by using Crystal Palace instead.
At 200kW, Crystal Palace is among a few of the most powerful transmitters in the country. Heathfield at 20kW (for PSBs) and 10kW (for COMs) is relatively low power 'high power' transmitter. The high power helps reach people, particularly those who have an obstruction such as a hill in the way. Choose how powerful a transmitter is, though, there will always be those who are struggling and would have been in a better position had it been more powerful.
My cursory assessment of Oxted leads me to believe that TV reception is either Crystal Palace or Heathfield, neither of which may be great. The only remaining question is whether Reigate may be possible. I tried a couple of postcodes in the predictor and it didn't come up, and I get the feeling that Oxted is beyond its coverage area, although as I say, a full postcode is really required to get any useful idea.