All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
julie: Queries about reception can only really be answered with knowledge of the location, this being in the form of postcode or that of a nearby property such as a shop. This is for the purpose of checking on expected signal levels.
In general though, aerials that worked for the former analogue should be expected to receive BBC, ITV, C4, C5 etc without any requirement for any booster that wasn't necessary before.
Has the problem just started?
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Nick Anderson: No!
Although I'm sure that politicians would love this to be the case, engineers have yet to re-engineer the laws of physics and make signals stop dead at predefined boundaries.
What will happen, though, is the signal will be broadcast from a directional antenna, as shown on the page for the Rowridge transmitter - click "LSOH" on the map. Don't draw too much from any "line" formed around the edge of the coverage map.
One warning: the Local multiplex will apparently only be broadcast horizontally, as too will the two new HD multiplexes. All channels are within Group A, so an aerial installed in the days of analogue should work. A wideband yagi aerial is not advised for Rowridge.
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julie: Definitely not!
You are just over 9 miles from the Emley Moor transmitter which is very powerful and therefore very strong in the Wakefield area.
If you go up on your roof you may even be able to see the red lights on the tower.
The first thing to check for is that, for BBC services, you are actually tuned to the signal from Emley Moor and not that of Belmont in Lincolnshire, or perhaps Bilsdale on the North York Moors.
Bring up the signal strength screen on BBC One. It should tell you what UHF channel/frequency it's tuned to. For Emley Moor it is C47 (682MHz); Belmont is on C22 (482MHz) and Bilsdale is C26 (514MHz).
For ITV, it should be tuned to C44 (658MHz).
It might have tuned to Belmont as it is picked up before Emley Moor during the scan, owing to the fact that it broadcasts on a lower frequency.
Unplugging the aerial lead for the first 30% of the scan should miss out Belmont and Bilsdale if it proves to be the problem. If your TV, having carried out the scan, gives you a choice of region, select "Yorkshire".
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Stewart: I too wonder if the issue is too strong a signal. Perhaps the tree foliage reduces the strength just enough so as not to be OTT. There are, after all, a lot of trees that could be in the signal path, and I'm not just talking about those in Rusthall.
See this terrain plot:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
The yellow line is the straight line between you and the transmitter. The pink line indicates the first Fresnel Zone (look it up). Anything within the first Fresnel Zone could, potentially, affect the signal.
In the direction of the transmitter, the ground goes upwards slightly up to the edge of Rusthall. The other thing to note is that at approximately 1.8 to 2.2 miles away the ground rises, although probably not enough to block line-of-sight. However, because the line-of-sight comes closer to the ground objects on the ground may intercept the line-of-sight and will certainly be within the first Fresnel Zone. That patch of higher ground is where Southborough is and on which sits Brokes Wood.
If you have a amplifier (booster) then remove it, or at least turn it right down. You might need to look at fitting some attenuation to bring down the signal level.
Try unplugging the aerial lead and holding it close to the socket and see if that improves matters. Do it whilst viewing the signal strength screen.
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Stewart: Having looked closer at the contour lines at Southborough, I think you might be able to see over Brokes Wood and it is on ground which slopes downwards away from you. The properties and trees along Yew Tree Road could certainly be in the way.
Indeed, if you click the link below the plot to view the area between the two points, the link intersects Yew Tree Road at its junction with The Ridgewaye, which is about where the highest contour line indicating 125m crosses.
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Stewart: The last sentence should say "the line intersects Yew Tree Road at its junction with The Ridgewaye".
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Bharat: I suggest that you try another television or a set-top box in the room where your issue is. This would serve to either rule out possibility that it is the TV at fault (or else suggest that the TV is at fault). Swap the lead from the wall socket to the TV to discount that as a possibility.
If you've done that then you have to ask yourself what else can you check?
For example, if the aerial is on the roof and the cable runs down the wall and through the wall, on the other side of which is the aerial socket then there's probably not a lot more you can do.
I looked at your road on Streetview and couldn't see many TV aerials (I spotted one), although there are one or two satellite dishes. If yours is in the loft can you access it and check that the wires are connected?
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Bharat: The P1285 is a power supply only:
Power Supplies
It is used in conjunction with a mast-head amplifier, such as these:
Masthead Amplifiers
They are so-called because they are designed to be fitted outside on the mast. Because you can't have mains electricity outside, they require a separate power supply which feeds a safe low voltage up the aerial lead.
In your case the mast-head amplifier is, I assume, in the loft adjacent to the aerial. If the power supply is also in the loft then they are in close proximity, which is fine.
There are a number of possible reasons why you don't have a signal:
- fault with the power supply
- fault with the mast-head amplifier
- poor connection or wiring
I would certainly do away with using an amplifier behind the TV set. The one fitted in the loft should provide sufficient signal that it doesn't need amplifying further.
An f-connector is one which is threaded and therefore requires screwing together to ensure it doesn't come apart. The power supply in question is available with f-connectors or standard coax TV connectors that just push together (as on the back of a television). See:
Satellite, Television, FM, DAB, Aerial, Coaxial Cable, Plugs, Sockets, Connectors & Leads
What you're looking to do is disconnect the amplifier from the aerial - look for the box somewhere on the lead from the aerial to the power supply. Then connect the wire from the aerial to the wire going to the room where your TV is. The only thing is that I imagine that the gender of the connectors may be the same and so they won't go together.
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trio: View the signal strength screen whilst on one of the HD services and ensure it is tuned to UHF channel 21 (474MHz). If it's not then it's not tuned to the Sandy Heath transmitter.
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Monday 9 December 2013 6:48PM
dave sexton: Those in Lincolnshire, for example, whose aerials point to Belmont can have difficulties because broadcasts from the Continent which is in the same direction carry across the water.
There's not a lot that can be done. Even if another transmitter is available you never know whether that might be affected, the randomness of the inversion effect being unpredictable.
If you are using Rowridge transmitter which is on the Isle of Wight then you might benefit from switching your aerial to vertical, this being because it transmits horizontally and vertically. If your aerial faces France then this will help reduce the likelihood of co-channel interference from there because it uses horizontal polarisation for its main transmitters.