Alderney
England · TV and FM
Position 49.717715, -2.187295 Grid reference XD86507980 Nation England Ground height 66 m Antenna height 31 m Aerial group Group B — C35–53, the middle Polarisation Vertical BBC region South West/Channel ITV region Channel ITV news region Channel Parent transmitter Fremont Point Ofcom site number 12803 The position is our conversion of Ofcom's grid reference XD86507980 from OSGB36 to WGS84 [V] . Ofcom publish no latitude and longitude for television sites. The transform is verified rather than assumed: on the 3,403 radio records that carry both, it reproduces Ofcom's own coordinates to within 0.1 m. This page treats Alderney and Alderney as one mast. Ofcom's television and radio files share no site identifier, and the link here is inferred [I] from the name and position rather than confirmed. If they are in fact two structures a few hundred metres apart, the transmitter lists below are still each correct; only their being on one page is not.
On the map
Alderney is not the strongest signal anywhere the model predicts — it is shown here in place. That is normal for a relay, which fills in inside a main station's area.
Television This site carries the three public-service multiplexes and none of the three commercial ones, which is the normal arrangement at a relay — 1,059 of 1,169 sites are like this. Channels on SDN, ARQ A and ARQ B are simply not transmitted here, and no aerial will recover them; they need a main station. PSB3 (BBC B) is the UK's only DVB-T2 multiplex and carries every HD channel. Losing the HD channels while keeping the rest is therefore a single-multiplex fault rather than an aerial problem.
FM radio Services with no horizontal ERP radiate vertically only. A rooftop FM aerial is normally horizontal, so those will read weaker on a fixed installation than a car radio suggests — 803 FM services nationally are vertical-only. “Pattern” marks services with a published radiation pattern in that plane: 36 attenuation figures at 10° intervals clockwise from true north. Where one exists it is used in the coverage prediction, so those figures are directional rather than a circle. The television data publishes no equivalent.
Ofcom's notes SFN with Fremont Point.
Transmitter data is Ofcom's; every dataset and the terms it is used under are listed under sources . Coverage figures are modelled, not measured, and are systematically optimistic .