All posts by Steve Donaldson
Below are all of Steve Donaldson's postings, with the most recent are at the bottom of the page.
Chris.SE: Thanks for the link Chris. It's a shame it's not built in to the DVB standard as it would seem a useful feature which produce the sensible result of having BBC One HD on LCN1, BBC Two HD on LCN2 and so on, now that the programming of SD and HD are identical.
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Jen Franklin: Which transmitter does your aerial point to? Which way does your aerial point and are the elements horizontal (flat) or vertical (up/down)?
Looking at your road on Google Street View, aerials are pointing different ways, to different transmitters, a testament to the difficulty of reception in the area. At digital switchover a new transmitter started up in Bexhill, albeit carrying the PSB multiplexes, meaning many channels not available.
Many aerials are pointed to Heathfield, and if this is yours then it is down as having engineering works. As you are in a poor area for reception from Heathfield, if it is on reduced power then perhaps this would explain your issue.
The full list of Freeview channels is here:
Channel listings for Industry Professionals | Freeview
Which ones are you missing? The "Mux" column identifies which multiplex they are carried on. If you are missing one programme channel on a particular multiplex you will be missing them all because it is the multiplex which you are not received.
The main multiplexes are:
PSB1 = BBC A
PSB2 = D3&4
PSB3 = BBC B
COM4 = SDN
COM5 = Arq A
COM6 = Arq B
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The Freeview Detailed Coverage Checker conflicts with other sources on the ERP of the Lancaster COMs. It says they are 1kW, half power with respect to the PSBs.
All other sources I have found assert them to be 2kW:
- The Table of Digital Terrestrial Broadcasting Stations for Multiplex Licences, Version 20, 5 February 2020[1]
- The Ofcom 700MHz Clearance Plan spreadsheet[2]
- The Complete DTT Frequency Plan spreadsheet which I downloaded in 2013 and is essentially an earlier version of the aforementioned 700MHz Clearance Plan spreadsheet, it being the same format.
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Source links
[1] https://www.ofcom.org.uk/….pdf
[2] https://www.ofcom.org.uk/…xlsx
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Dave: Two possibilities spring to mind:
1. C47, which is the PSB3 or "BBC B" multiplex from Weymouth, is DVB-T2 whereas the other two channels are DVB-T. DVB-T stands for "Digital Video Broadcasting - Terrestrial" and DVB-T2 is the later version.
If on the manual tuning screen it asks you whether it is DVB-T or DVB-T2 then you need to select the latter for C47. If it doesn't ask you then it must work it out automatically.
2. This one only applies if it is a really old TV. Originally, when TVs began being HD, they were sold as "HD Ready". This caught a lot of people out because they thought it meant that the TV was "ready" to receive and show HD pictures when they began broadcasting. HD Ready sets were available around the time of digital switchover.
A HD Ready set can show HD pictures (such as inputted via a HDMI lead) but cannot receive them because it does not contain a DVB-T2 tuner. At the time, the DVB-T2 standard had either not been defined or was in its infancy. I think the latter may have applied, but the point is that back in the late 2000s or early 2010s HD Ready sets were sold. I can't remember the exact timeframe, but you get the idea that there was a time when TVs could show HD pictures but not receive them. It may be unlikely, being that it is so old, but I mention it anyway just in case.
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Brian Butterworth: A hyperlink to Weymouth leads to the Wye transmitter page. The Wye transmitter page has "Wyke" at the end of its URL, rather than "Wye".
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Dave: Is this a new or recent issue, or is it a longstanding one they you've never found a solution to?
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Pete Howell: This is a problem with automatic tuning in situations such as yours, where more than one transmitter is being picked up by the aerial. It was equally an issue in the days of analogue, since when manufacturers began incorporating automatic tuning.
If you can manually tune in the desired channels, having wiped the tuning memory, and the TV doesn't change it at some point, then that's all well and good -- you have solved the problem. However, if the TV takes it upon itself to retune with such functionality unable to be disabled, then the problem still exists. It is not the presence of the unwanted Wenvoe signals per se, but the fact that the TV automatically retunes outwith user control that is the problem. This is a real-world scenario which the TV is not designed to deal with.
As has been mentioned elsewhere on this site, automatic tuning can be more trouble than it's worth. There is automatic tuning that the user invokes during set-up and then there is that which runs periodically without user intervention, usually when the set or box is turned off. While the user can avoid the former by using manual tuning, if the manufacturer hasn't included an option in the settings to turn off the latter then this may be a nuisance and in fact totally negates the benefit of having manually tuned in the first place. Essentially, the TV takes it upon itself to do what it likes anyway, regardless of the user having programmed it to their own preference.
Where there is no option to deactivate periodic automatic retuning, it may be worth badgering the manufacturer for a firmware update that includes one. In the real world, signals from more than one transmitter may be coming down the aerial lead. Designers who fail to allow automatic retuning to be switched off are evidently not living in the real world.
I have been thinking about your situation and will go on to discuss what I think may be a possible solution to filter out the unwanted Wenvoe channels. I'm a technical bod rather than an aerial installer, hence I said "I think" this may be a possible solution because I don't have first-hand experience. It's something I might have tried were it my problem. If you like technical challenges then this is something you might like to do. Apologies if it goes over your head.
I've included links to retailers and some eBay listings. These are for information only, and are in no way advocation of a particular seller. Do your own checks and satisfy yourself such as by looking at feedback if you are interested in the products. Other products and suppliers are available, as they say.
I should add that in the above posting giving the channel numbers I missed off UHF channel 31 from the Kings Weston transmitter. This is the Local TV multiplex. It isn't as powerful and doesn't have the same spread as the other, main multiplexes. Therefore, not everyone receiving the main channels can also get the local multiplex. If you can receive it, however, then this means there are seven channels you need to tune and receive, if indeed you want to have it available on your TV.
Over the last decade or so 20 of the top-end UHF channels have been cleared for use by mobile phone networks. The highest is now 48, having previously extended all the way up to 68. The remaining 21 to 48 range is divided into two groups: A and B. An explanation of groups is here:
Wideband / grouped TV aerials A.T.V. Poles, Brackets, Clamps & Aerials
As you can see, the groups have changed somewhat, owing to the clearance of the top channels. The former C/D group is now completely gone, for TV broadcasts.
To return to your problem, Kings Weston's COMs and Local TV (4 channels) are Group A, and the PSBs (3 channels) are Group B. All Wenvoe's channels are Group B, thus you can't simply filter out Group B channels and allow Group A ones through.
Filters are available at reasonable cost for ranges of channels. For example:
https://www.blake-uk.com/search/proob
As I say, unfortunately, KW's PSBs are within the same range as the Wenvoe channels, so it's not possible to use one of these -- on its own, at least.
As the wanted and unwanted channels are immediate neighbours then you will require filtering for individual channels. In Group B, you want to allow through 40, 43 and 46, while filtering out 39, 41, 42, 44, 45 and 47.
I would think that such filters will be quite expensive, not like the group ones above. Perhaps a second-hand one such as off eBay may be the way to go.
If you like a challenge, here are my thoughts on how you might affect a solution.
You will need:
- a two-way splitter
- a four-way splitter
- a Group A filter
- a programmable-channel/tunable filter
- adaptors, plugs and coax cable (or leads already made up) as required, depending on the desired configuration
I should say that there will be some degree of loss. Any filtering will bring with it loss, but this may be small.
If you have a distribution amplifier which sends signals to different rooms, then you may wish to put the filtering before it so that all rooms get the benefit of a Wenvoe-free feed.
Here's what to do with the parts:
Connect the two-way splitter onto the end of the incoming aerial cable. Connect the Group A filter onto one of the outputs of the splitter. The output of the Group A filter therefore gives you the COMs (22, 25 and 28), along with Local TV (31) if applicable.
Onto the other output of the splitter, connect the programmable/tunable channel filter. I found this, which ironically comes pretuned to Wenvoe's four former analogue channels and is from a seller in Wenvoe's coverage area: https://www.ebay.co.uk/itm/275505497020
As you can see, it has one input and four outputs which can be tuned to any channel. You need only three. Tune them to 40, 43 and 46. Connect the input of this filter to the other output of the two-way splitter.
You then have the incoming splitter which goes two ways. One way goes through the Group A filter, giving you 22, 25, 28 and 31 (and all other Group A channels within range of the filter). The other goes through the programmable filter, which gives you 40, 43 and 46, each on a separate output.
Take the four way splitter and use it in reverse, as a combiner rather than a splitter. The four inputs for the combiner will be: one from the single output of the Group A filter and each output of 40, 43 and 46 on the programmable filter.
You will need adaptors (IEC to f-connector) and connectors (IEC and/or f-connectors) as required. If the splitters and filters have threaded f-connectors instead of push-in IEC plugs/sockets (found on TVs and set-top boxes) then you will need some form of adaptor. To connect the output of the Group A filter and the three filtered channels you will need short lengths of coax, probably low-loss and double shielded as it can be terminated with f-connectors.
Here are a few closing comments:
If you put 'teldis filter' or 'polytron filter' into eBay (without quotes) you will find more filters. Equivalent products may be available from other manufacturers and more work may be required to uncover them. There is a five-channel Polytron one currently listed. I doubt you will find one that will do seven channels. You would need a seven-way filter (to use as a combiner) and I'm not sure that they're available. With such a configuration you wouldn't need the separate Group A filter.
The filter I linked to on eBay (Teldis SCL 114) is very old. The telephone dialling code printed on the label does not include the '1' after the leading zero, hence tells us it pre-dates April 1995.
This from Teldis says that the SCL (Single Channel Levellers) "are for analogue television services only":
https://teldis.co.uk/images/pdf/Digital%20and%20Analogue%20Channel%20Levellers.pdf
I don't know why it says this. It looks like the document was written before switchover, when there was the low-power digital fitted in around the analogue. Iwould have thought it wouldn't matter. If someone can shed more light on why it says this then it may be useful. Obviously with four filters and outputs, it doesn't cater for more than four channels and it did cater for the four-channel analogue. But a cluster of channels is no good here because wanted and unwanted are on adjacent channels.
I don't know whether the other output on the programmable filter needs a dummy load on it or whether it can be left without anything connected to it. When you have a splitter with multiple ways and one or more is not connected to anything it is unbalanced, and really should have a load, known as a terminator: https://www.aerialsandtv.com/knowledge/splitters-amps-and-diplexers#amplifier-terminators
If you have a masthead amplifier, then the power supply for it may need to go before the filtering solution.
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Chris: There has just been another report from someone in CB24, north of Cambridge, with the same issue. This is roughly north east out from the transmitter:
Sandy Heath (Central Bedfordshire, England) Full Freeview transmitter | free and easy for 21 years
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Tom: You're the second person to report an issue with the HD multiplex of Sandy Heath this evening. See this other comment:
Final Freeview retunes to allow 5G mobile at 700MHz listed | free and easy for 21 years
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Sunday 5 November 2023 6:06PM
Jody: It's because the TV which has not done the swap pre-dates the capability to do the swap!
Changes to BBC HD channels as Freeview HD swap rolls out > RXTV info
The capability to replace SD channels with their HD variant has only been devised and made available in the last few years. This is as a response to the obvious, which is that the HD variants should take up the logical channel numbers of their SD counterparts where they exist (instead of languishing in the 1xx range). When the system/standard was devised in the first place, this wasn't thought of and was not an issue or requirement.