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 JACKSON: The Rye relay transmitter broadcasts on UHF channels 40, 43 and 46 which are the same as the three COM channels of Heathfield. Rye is vertical polarity, while Heathfield is horizontal.
Thus, should you experience poor reception on these channels, a possible suspect is interference from Rye. Your aerial is obviously horizontal, but it might still pick up the vertical signal from Rye to some degree.
The COM channels are COM4 (SDN), COM5 (Arq A) and COM6 (Arq B). For a list of programme channels carried on each of these and the other multiplexes, see the Freeview list:
Channel listings for Industry Professionals | Freeview
The three PSB channels of Heathfield, PSB1 (BBC A), PSB2 (D3&4) and PSB3 (BBC B) are not shared with Rye.
The COM channels of Heathfield and the three Rye channels have been the same since 16 October 2019.
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margaret: The channel numbering varies by platform. What platform are you watching on?
ITV2 is on channel 118 on Sky and channel 113 on Freesat. On Freeview (terrestrial TV) it is on channel 6.
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M Wickham, Bob Reeve: It sounds like the issue could be related to the work at Rowridge. The multiplex (PSB2) which carries ITV1, Channel 4 and others is received off-air from Rowridge by Patcham. The two other multiplexes are the responsibility of the BBC and arrive at the transmitter over fibre.
A single digital TV broadcast signal known as a multiplex or 'mux' carries multiple programme channels. This is unlike with analogue where each programme channel was transmitted on a signal of its own. Thus, loss of a single multiplex will result in loss of multiple programme channels. It is a case of working out which multiplex or multiplexes are missing.
Patcham transmits three multiplexes, the three PSBs, or public service broadcasters.
PSB1 - BBC A - BBC standard definition TV and BBC radio
PSB2 - D3&4 - ITV1, Channel 4, Channel 5 and some ITV1 and Channel 4 sister channels
PSB3 - BBC B - All HD channels, BBC and non-BBC
Freeview has published a list of programme channels and which multiplex they are carried on here:
Channel listings for Industry Professionals | Freeview
Rather than resetting and carrying out automatic tuning, use the manual tuning facility to scan the appropriate UHF channel for the required multiplex from Patcham. Automatic tuning takes time and looks through all the channels. Manual tuning focuses in on only the actual channels that are used and which are required. Channel numbers for Patcham are:
PSB1 - C29
PSB2 - C31
PSB3 - C37
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Dennis Anthony: This begs the question: are you sure?
At your location there look to be two potential transmitters: Heathfield and Hastings (Bohemia). Heathfield is horizontally polarised and Hastings is vertically polarised. It sounds like your aerial might have been changed from the former to the latter.
UHF channel numbers for each are as follows:
- Heathfield -
PSB1 - BBC One - C41
PSB2 - ITV1 - C44
PSB3 - BBC One HD - C47
COM4 - QVC - C40
COM5 - Sky Mix - C43
COM6 - Quest - C46
- Hastings -
PSB1 - BBC One - C25
PSB2 - ITV1 - C28
PSB3 - BBC One HD - C22
COM4 - QVC - C23
COM5 - Sky Mix - C26
COM6 - Quest - C30
Check which you are tuned to by viewing the signal information/strength screen on each of the above programme channels.
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Paul Evans: While you may have line-of-sight to the transmitting antenna at the top of the mast, the Malvern Hills are well within the Fresnel zone, meaning they could potentially cause reception difficulty. This isn't to say it will.
The radius of the Fresnel zone varies according to frequency, the lower the frequency the longer the wavelength and the bigger the radius. It is largest half way between the two antennas, getting smaller the closer to the two antennas.
The radius of the Fresnel zone as the signal passes over the Malvern Hills is in the region of 82m to 87m. However, line-of-sight at this point is only around 20m above ground at its closest point, this judging by the following terrain plot:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
If the reserve antenna is in use, then line-of-sight runs even closer to the ground over the peak, as this is lower down the mast.
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Paul Homer: None of the BBC Three Counties Radio FM broadcasts are good along that stretch of the M25.
If you manage to receive it all the way along the M40 to the junction with the M25, then I guess you must be tuned to High Wycombe on 98.0. You may be able to pick it up on 92.1 from Hemel Hempstead (Pimlico) from around junction 18 in the Micklefield Green area, or perhaps sooner. The six or so miles in-between these two points is where reception is most difficult.
RDS Alternative Frequency (AF) can be useful in keeping tuned to a station having moved from an area where it is on one frequency to where it is on another. However, it only works where the alternative signal to be switched to is strong enough for the radio to be able to decode the RDS. In this instance, you are looking to receive the station outside the area where the signal is strong enough to offer RDS on any of its frequencies.
Thus, when driving clockwise from the M40 towards the junction with the M1, for example, the radio will not switch to 92.1 until the signal gets strong enough for it to decode the RDS data, which will probably be after the point at which the signal can first be received. Thus, you may have to manually tune between the frequencies, perhaps having stored each under a different preset. Depending on how the radio works with respect to AF will depend on how easy this is -- different radios work differently.
With some radios, AF cannot be turned off, and this can be a nuisance. In other cases it can be set as on or off per preset, or on or off for all presets together (in the settings menu). If it's possible to turn it on/off per preset then this is the easiest to work with: store the frequencies under different presets with AF off. Then change as you move, working out where each is best.
Coverage maps by transmitter/frequency for FM stations are here:
http://a-bc.co.uk/mca-measured-coverage-area-maps/
The coloured area shows where the signal level is projected to be at or above a predefined level. This isn't to say the broadcast can't be received outside that area. But as you can see, the coloured area for 92.1 begins around Micklefield Green. The question is, how far before that point can it be picked up well enough to listen to, without too much hiss and intermittent fading?
Judging by coverage maps I guess that 103.8 might be the one to try first along that length of the M25. Much of the motorway there runs north/south and the transmitter is roughly due north, so in line with the road which runs in a cutting along some of its length.
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John Dennis: This full list of Freeview programme channels is here:
Channel listings for Industry Professionals | Freeview
This indicates which multiplex (mux) each is carried on. The six main multiplexes are:
PSB1 = BBC A (BBC standard definition TV and BBC radio)
PSB2 = D3&4 (ITV1, Channel 4, Channel 5 and others)
PSB3 = BBC B (all HD channels)
COM4 = SDN
COM5 = Arq A
COM6 = Arq B
How is COM4 reception? Is the quality down on this channel? What about the three PSB channels?
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Rai: The Freeview predictor gives glowing '100' scores across the board for all six main multiplexes and the local multiplex from Black Hill at your postcode, suggesting excellent (the best) reception. I think this may be over-egging the pudding somewhat.
The ground level at properties in your postcode is around 15m give or take a few metres. 200m or so to the east, in the direction of the transmitter, the ground is 20m or more higher on which there is the school, church and several apartment blocks.
The higher ground can be seen on this heat terrain map:
https://en-gb.topographic-map.com/map-cgt/United-Kingdom/?center=55.85278%2C-4.35936&zoom=16
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Mr. A. Phillips: This website is not affiliated with any of the broadcasting companies. It is entirely independent.
Freeview lists transmitter engineering works on this page which you might like to bookmark for future reference:
Planned engineering works | Freeview
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Saturday 20 April 2024 6:25PM
CHRIS JACKSON: As StevensOnln1 says, there is the posting above yours that Heathfield has engineering works. The 'Transmitter engineering' information above is sourced from this page on the Freeview site:
Planned engineering works | Freeview
Another possible cause to consider is interference by a nearby mobile phone base station operating on a frequency previously used for TV. Restore TV is the organisation charged with alleviating such issues and will send out a free filter. A lookup of your postcode on the Restore TV says postcards have been sent there, meaning there could be an issue: https://restoretv.uk/post…ure/
While we cannot say for certain where the base station is, I see there is the water tower with antennas on overlooking you. I suggest you make enquires with Restore TV to receive a filter.
If you have a rooftop amplifier then any filter will need to go before this, meaning it will need to be on the roof. Tell Restore TV you have a rooftop amplifier and they should send an engineer to fit a filter on the roof for you.