Hammersmith
England · TV
Position 51.492931, -0.226765 Grid reference TQ23207860 Nation England Ground height 2 m Antenna height 55 m Aerial group Group A — C21–37, the low end of the band Polarisation Vertical BBC region London ITV region London ITV news region London Parent transmitter Crystal Palace Ofcom site number 10164 The position is our conversion of Ofcom's grid reference TQ23207860 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.
On the map
Hammersmith 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.
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 .