All posts by Steve Donaldson
Below are all of Steve Donaldson's postings, with the most recent are at the bottom of the page.
Gary: Parent transmitter Stockland Hill is presently listed for engineering works, so perhaps this is the reason:
Planned engineering works | Freeview
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Christopher Sercombe: I see there are six properties in your postcode. Four are on the north side of the road and two on the south side.
The path to the transmitter is along the line of the road, or almost, meaning that aerials are directed along the apex. This likely rules out any possibility of mounting the aerial on the front or rear wall because it would have to point along the wall and the wall will therefore impact the signal.
Having looked at Google Street View photos and satellite images, the four houses on the north side do not appear to have any tree that could potentially cause difficulty. However, the two on the south side clearly do. If I had to guess, you live in one of these houses. There is not one shared chimney at the party wall on which the aerials are mounted. Rather, each has its own chimney half way along, hence one aerial is closer to the tree than the other. It still begs the question whether the immediate neighbour has any issue with reception too.
While the tree is fenced off from the pavement by metal railings, there is another wall between the ground it is on and the house immediately adjacent to it. Skipping back to the May 2009 Street View photo I see that where there are now railings there were concrete bollards then. The ground was trimmed grass and now it is overgrown. A check of the map on the local planning register has the area the tree is on coloured green, implying it is common/public land and not part of the house it is adjacent to.
If you are indeed in one of these two properties then you might be looking at the situation as a problem that may be impossible to overcome. After all, it is not within your power to prune the tree and the only way around it would be to mount the aerial on a very very tall pole, and even then the aerial would still be pointing through the canopy. You're snookered, basically.
I think there's a relatively easy answer: mount the aerial down your garden on the shed or other outbuilding such as the garage. At your location it would seem likely that reception at lower level may be good. Looking at the backs of the two houses from Sycamore Grove (on Street View) I can see over the wall. I can see that the property closest to the tree has a single storey extension on the rear. There is the question of whether it would be desirable to have an aerial on this both from aesthetic perspective and in terms of whether it would be possible to attach one. I'm not sure either way. Attaching an aerial to anything you have to consider the effect of the wind blowing on the aerial and mast -- it's not just a case of the weight of the mast and aerial on their own, there is wind-loading.
This then leaves the shed. I see both gardens have a shed at the end, both of which are alongside the fence. The cable could be run along the fence to the house. I would give some thought as to whether to use nailed cable cleats or some other method, such as some type of adhesive that will adhere to the surface it needs to stick to. Whether it is your fence or that of your neighbour may also have bearing on the approach. The other possibility is some form of conduit buried just under the soil alongside the fence line, although this will need appropriate waterproofing so it doesn't become filled with water. It's rather pointless feeding a length of cable through conduit to give it protection from the elements if you leave the ends open for rainwater to come in!
When affixing it to the shed, use wood screws that are long enough to go through the wall into one of the studs on the inside so as to give it strength. Use a proper wall bracket and pole, not a loft bracket and 90 degree pole as these are really meant only for inside a loft where there is no wind blowing.
ATV in Sheffield has some extensive information on its website (other suppliers are available):
Poles and masts A.T.V. Poles, Brackets, Clamps & Aerials
A log periodic has low wind-loading and is one of the least aesthetically intrusive TV aerial types:
Log Periodic aerials A.T.V. Poles, Brackets, Clamps & Aerials
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Geoff: In short, the Budleigh Salterton transmitter does not carry any DAB+ stations.
I'm not exactly sure how a DAB+ station will appear as I don't use DAB. If the radio does not have DAB+ I believe the station will appear in the menu listing but it will not play the audio.
Having just checked the latest Ofcom spreadsheet of radio transmitter parameters, the Budleigh Salterton transmitter broadcasts two DAB multiplexes: "BBC National DAB" on 12B and "Devon" on 11C.
On each multiplex, each individual radio station can be either DAB or DAB+. The spreadsheet lists the stations carried on each multiplex but does not say whether they are DAB or DAB+.
The Devon multiplex is operated by Now Digital, a subsidiary of Arqiva, the company which runs pretty much all TV transmitters and other transmitters in this country. This page is about the local multiplexes it operates, written as proposition to prospective broadcasters rather than aimed at the listener:
https://www.arqiva.com/me…-dab
It does however answer your question and that is that there are no DAB+ stations on any of Now Digital's multiplexes because the equipment is not capable.
All stations on the BBC National DAB multiplex are DAB, not DAB+.
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Billy: While engineering works is a possible cause, another could be the presence of a new mobile phone base station operating in the 700MHz band, a band which was previously used for TV. Restore TV [ https://restoretv.uk/ ] is the organisation responsible for addressing problems of interference to TV reception caused by these base stations. It says your postcode has received a postcard telling you that you are in an area that could potentially be affected. This isn't to say it will definitely be the reason for the issue because it isn't an exact science. Contact Restore TV and they should send you a free filter.
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Christopher Sercombe: I'm surprised you're using a loft aerial. I can see you have a rooftop aerial. Indeed, I looked closer at the series of Street View photos and saw that both you and your neighbour had your aerials replaced some time between May 2009 and June 2014, when the first and second photos of the road passing your house were taken. May I ask why you are not using your rooftop aerial?
I was thinking about your neighbour and that if you were having difficulty with reception via your rooftop aerial then your neighbour may be, as his/her aerial is closer to the tree.
Having looked a little along your road and nearby streets, I can see there are a number of trees. I would have thought the council must have a plan on maintaining them and wonder why the one near you is not being maintained. Indeed, in May 2009 it was much smaller than it is now, albeit that even then the top of the canopy was above your apex.
Noting you have Wiltshire Council as a unitary authority and Trowbridge Town Council at parish level, it begs the question as to which council is responsible for it. If you haven't already done so I would raise the matter with elected councillors of your wards at both levels.
Engaging with the department responsible for the environment, one is seeking to have something done. It is civil servants you are dealing with who follow procedures. By contrast, elected members are there to represent their constituents (or supposedly at least), and they may be able to exert influence in the necessary place to get a result.
Potential damage to building foundations is one such issue, and of course your neighbour has it overhanging onto his/her property. There is also the aesthetics of the overgrown ground around it. I guess having put the railings there then the council stopped coming along to cut the grass.
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Alexander Scott: The first thing to check is that your TV is in fact tuned to Preseli and not Carmel, which would mean that the broken or non-existent picture you have been watching is actually from Carmel. The other thing to note is that there is a mobile phone mast which could potentially (but in no way definitely) be interfering with TV reception at your postcode. There are other possible causes of the issue, such as a problem with your aerial system, but I will expand on these two for now.
You may know this and be familiar, as it is a common issue, even back in the days of analogue. At your location Carmel is in the opposite direction to Preseli and it is on lower UHF channels, thereby being found before Preseli during the TV's automatic tuning scan.
The channels for Preseli are:
PSB1 - BBC One - C43
PSB2 - ITV - C46
PSB3 - BBC One HD - C40
COM4 - QVC - C42
COM5 - Sky Mix - C45
COM6 - Quest - C39
Check the signal strength screen for the programme channels shown above to see that the UHF channel numbers, prefixed 'C', are those of Preseli.
For reference, Carmel's in the same order are: 23, 26, 29, 33, 36, 48
If the TV is tuned to Carmel then this needs correcting. Manually tuning the six Preseli channels may be the only way to achieve this effectively and easily.
The other observation I have made is that Restore TV says it sent postcards to your postcode notifying you of the fact that a mobile phone base station in your area had begun operating in the 700MHz or 800MHz bands, these previously used for TV, and that this could potentially cause interference with TV reception. Restore TV is the organisation charged with alleviating such issues and will send out a free filter to block the higher frequencies now used by mobile phones.
I note there is the nearby lattice tower at the fire station with mobile phone antennae on. While it is supposition and isn't forced to be this mast, it is nonetheless close by.
If you have an amplifier (masthead amp) with your aerial then the filter will need to be fitted before it, so that the mobile phone signal does not enter the amplifier. In cases where someone has a masthead amp then a waterproof outdoor filter is supplied, and you will need to tell Restore TV this when you ring them. They usually send an engineer to fit it. However, this is usually on the rooftop, and if your aerial is on a pole I have no idea whether they can do this, if it means climbing the pole to access it.
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Alexander Scott: Information about and contact details for Restore TV is here: https://restoretv.uk
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John Todd: Whitehawk Hill is not listed by Freeview as having engineering works:
Planned engineering works | Freeview
This doesn't necessarily mean for certain that it isn't, assuming that works can always overrun and perhaps not be listed.
Another possibility, other than transmitter works, is interference by a mobile phone base station and/or mobile handsets/devices in the 700MHz or 800MHz frequency ranges, these frequencies formerly used for TV. Restore TV is the organisation responsible for alleviating such interference. They will provide a free filter to prevent the unwanted mobile signals getting into the TV/set-top box.
If you have an amplifier then the filter should go before it. If the amplifier is on the roof then this will require a special outdoor, waterproof filter. Restore TV should send an engineer to fit this should it apply here.
Details for Restore TV are here: https://restoretv.uk
One of the FAQs relates to having more than one TV. It says they will send more than one filter on request. I don't know whether they will send one filter and ask you to try it on both TVs and get back to them if you need a second, or whether they will send you two filters.
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Craig William simm: Vertical polarity, so as to reduce susceptibility to interference from distance transmissions, particularly from France. However, the local multiplex on channel 37 broadcasts only horizontally so using VP may sacrifice the local mux, or may make it poor or variable.
The multiplexes of Rowridge are:
PSB1 - C24
PSB2 - C27
PSB3 - C21
COM4 - C25
COM5 - C22
COM6 - C28
Local - C37
Transmission powers are 200kW for the HP PSBs, 50kW for the HP COMs and 200kW for the VP PSBs and VP COMs. The local multiplex is 10kW, although this uses a signal mode which offers greater coverage for less power, so in a way it's actually more powerful than it looks when compared to the others.
In respect of the COMs, 50kW is in no way insignificant. At 200kW Rowridge is among the highest power transmitters in the country. Some of the main transmitters that aren't as powerful are less than 50kW.
I have been unable to find Stock Dove Gardens. I suspect it's in the new development at Boorley Green. While the Freeview Detailed Coverage Checker suggests good reception at the postcode, there are two points to bear in mind:
1. There is the question as to whether the Checker has the correct geographic location for the postcode, being that it appears new. For example, some maps I tried plotted it at Durley.
2. Even if it is the correct location on the ground, the predictor may not be taking into account the fact that there are houses on the ground because it might not have been updated to reflect this yet. Unless you happen to be on the edge of the development facing the transmitter (where there is clear space in that direction) then you may have bricks and mortar of other properties causing some level of shadow which the predictor might not be factoring in.
Another factor to consider is possible interfering transmitters -- those which are on the same channel(s) (co-channel) and which may carry further than normal at some times, thereby degrading reception. The two closest and most obvious potential occasional interferers are Mont Pincon and Saint Pern. The thing is that in pointing your aerial at Rowridge, you are also pointing it the direction of these other transmitters (albeit much further away) which are on the same channel.
Mont Pincon is in Normandy, around 20 miles south west of Caen. It uses channels 22, 25 and 28 with horizontal polarity and with an effective radiated power of 100kW. So it is co-channel with Rowridge's COMs. It is about 25 degrees anti-clockwise of Rowridge from the Boorley Green area and around 139 miles out.
Saint Pern, near Rennes, uses 21, 24 and 27 at 80kW with HP, so co-channel with Rowridge's PSBs. It is 185 miles out and on the same bearing as Rowridge from Boorley Green (give or take a degree or two).
The advantage for using VP is not only to get a stronger signal on the COMs but to reduce susceptibility to co-channel interference. The objective is twofold. It is to increase the ratio between the wanted (Rowridge) and the unwanted (other transmitters which are co-channel). This is done by increasing the level of the Rowridge COMs by using VP, while at the same time VP lessens the level of the HP signal you will pick up from unwanted distant transmitters (should they reach you), of which I think I have identified the two closest and most obvious.
The only problem with all of this is that the local multiplex is HP only. How important is this to you? VP may provide for more resilient reception of the main Freeview channels at the expense of the local mux, which may or may not be receivable to some degree because the aerial is at the opposite polarity to its signal.
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Friday 1 December 2023 5:14PM
GRAHAM DOLPHIN: I make two observations: Catherine Hill will be the source of difficulty with reception in the area. Also, mobile phone networks and devices connected to them may be a source of interference. If you haven't already done so, I suggest you use vertical polarity for reception, turning your aerial so it is vertical (elements up/down) rather than horizontal (elements flat). Also, enquire with Restore TV about a filter to block any mobile interference.
On Catherine Hill are lots of trees. The trees change throughout the seasons and throughout the day, and therefore this could account for the observation that the issue is particularly prevalent at one time of year during a particular part of the day.
At your location the other transmitter that may be available is Winterborne Stickland. This is in the exact opposite direction to Rowridge, the exact same distance and not as powerful, although it would appear that there may be line-of-sight. It also doesn't carry all the Freeview channels (it is PSB-only, no COMs -- more on this below). I can see on Google Street View that some houses on Rydal Close have (or had) their aerials on Winterborne Stickland (at least they did in August 2012 when the photos were taken). From what I can see, those at the far end of the road are/were all on Winterborne, with some Rowridge users at and near the end with junction with Hillside Drive.
Uniquely, Rowridge broadcasts with both horizontal polarity (HP) and vertical polarity (VP), and has done so since digital switchover in March 2012. The transmission powers of the multiplexes are not all the same and vary between HP and VP. I suggest, if you have not already done so, that you use VP.
Also on Google Street View, from a photo taken at the junction with Hillside Drive in May of this year numbers 1 and 4 Rydal Close now have Rowridge aerials set vertically. Both appear to be the same aerial (log periodic type), so I might speculate that they could be by the same installer. In the previous photo of August 2012, number 1 had its aerial set horizontally on Rowridge and little above the apex. It is now higher up, is a different aerial and is vertical. Number 4 was using Winterborne Stickland and now has a new aerial on Rowridge. One reason to switch to Rowridge is to get the full complement of channels.
With digital broadcasts, multiple programme channels (services) are carried by a single signal, known as a multiplex or "mux". There are six main multiplexes (six signals), three PSBs (public service broadcaster) and three COMs (commercial). Winterbourne Stickland, as with many relays carries only the PSBs.
Rowridge broadcast (UHF) channels are:
PSB1 - "BBC A" - BBC One etc. - C24
PSB2 - "D3&4" - ITV etc. - C27
PSB3 - "BBC B" - BBC One HD and other HD services - C21
COM4 - "SDN" - QVC etc. - C25
COM5 - "Arq A" - Sky Mix etc. - C22
COM6 - "Arq B" - Quest etc. - C28
The full list of Freeview services by multiplex is here:
Channel listings for Industry Professionals | Freeview
In terms of the transmission power used by Rowridge, the PSBs are at 200kW HP and VP, while its COMs are 50kW HP and 200kW VP.
As well as transmission power, there is also the matter of distant transmitters which use the same broadcast channels. Across the transmitter network as a whole, the PSBs get the better channels, where there is less areas of overlap. The COMs often use channels which are reused by another transmitter at closer distance to the PSBs, hence there are more pockets of potential overlap, where a distant transmitter may be a source of interference.
With Rowridge, its COMs are co-channel to those of Stockland Hill to the west/north west (and Crystal Palace to the north east, covering London). By contrast, Rowridge's PSBs are not co-channel with Stockland Hill (or Crystal Palace). This explains the COMs being at quarter power. At your location, Stockland Hill is roughly in the opposite direction to Rowridge at 57 miles out, although there is high ground in the way, particularly that north of Dorchester.
This therefore presents another reason to use vertical polarity. Stockland Hill transmits only with HP, hence an aerial set vertically (for Rowridge) will have more rejection of the unwanted HP signal of Stockland Hill. The same may go for distant stations, whether in the UK or on the Continent, when atmospherics result in signals carrying much further than they normally do, although it is not to say interference will never occur, just that the aerial set for VP may be expected to help lesson it generally.
On the other observation I have made, the potential for mobile phone interference, Restore TV [https://restoretv.uk] is the organisation responsible for alleviating issues caused by mobile phone base stations and associated devices from interfering with TV reception. It says your postcode has received a postcard informing you that you might suffer interference. Emphasis here is on the "might" because it's no where near an exact science.
Suffice to say that if there are no phone base stations operating in what was formerly the top portion of the TV band of frequencies (700MHz and 800MHz bands) then there cannot possibly be an issue. So, that it says you have received a postcard tells us there is at least one base station in the vicinity which could potentially be an issue.
I see the lattice mast on Street View on Catherine Hill, a little anticlockwise of the direction of Rowridge. I can also see there are in fact two adjacent towers, and it wouldn't surprise me being in such a prominent position above the surrounding area if these towers are home in the area to all four of the mobile networks. This isn't to say this is the potential cause, but if it is (meaning if it is operating on 700MHz and/or 800MHz) then it could potentially be.
If you haven't already done so, then give Restore TV a ring and they should send you a free filter. If your aerial feeds into an amplifier before reaching your TV (whether at the aerial or so as to feed more than one room), then it any filter will need to be fitted before it. If the amplifier is on the roof, with the aerial, then Restore TV should send an engineer to fit a suitable outdoor filter.
Being that it sounds like the problem has been going on year on year then it seems unlikely that any mobile phone interference is the sole cause, hence why I made this the second point.