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Sudbury Transmitter (& Sudbury B) OS Grid Ref TL 912 376
Note, as work takes place on various digital transmitters (to prepare for the DSO) you may
experience problems, e.g. with certain MUXES disappearing. First try rescanning your
TV / set top box (do it manually if possible), but if this fails to work check on Transmitter work
or call the reception advice phone numbers. Also see basic digital fault finding.
Sudbury was opened in 1968 for the transmission of BBC2 and then BBC1/ITV were added
in 1970, finally Channel 4 came along in 1982. It is horizontally polarised and was originally
a B group before the advent of Digital / Freeview, though most of the latter is still within the
same group. Analogue power is 250Kw apart from C5 which is only 50kW, for
Digital power see the accompanying table.
There are a few out of group issues, MUX 5 is on CH 54 though this is only one channel
above the band so would normally be receivable on all B group aerials, though possibly not
some crappy contract aerials though....... MUX 2 off Sudbury is on CH 68 and would not
normally be receivable off a B group unless you were in a very strong signal area. This
supplementary transmitter is called "Sudbury B", not to be confused with “B group(s)”,
and is mounted amongst the other Digital arrays) only transmits MUX2 on CH 56.
Unfortunately this is just where most B groups response falls off, though reception would
usually be fine in reasonable signal areas. Thus Sudbury is now an E group.
The figures for the mast heights vary according to which source you look at, but I reckon
the mast height for the original TX is about 140m (a.g.l) with the aerial array (covered by
its fibreglass shroud) on top of that, possibly another 20m. The second of the structures,
the one transmitting digital, is around 130m in total height, see How High is High ?
The site height is 70m and the TX is located about 14 miles WSW of Ipswich.
Sudbury`s approximate population coverage is just under one and a half million and it has
five small repeater transmitters off it.
Sudbury/Sudbury B have quite complex radiation patterns (see accompanying table and
the picture of the transmitting arrays) and it`s always worth considering another transmitter
if you are experiencing problems with reception from it, see co-
Co-
CH39 (MUX4) is co-
CH48 (MUX3) is co-
CH49 (MUX1) is co-
CH50 (MUX6) is co-
CH54 (MUX5) is co-
CH56 (MUX2 B) is co-
CH68 (MUX2) is co-
Plus co-
Sudbury Transmitters from the South. The original Sudbury transmitter is on the right and the Sudbury digital transmitter on the left. (All pictures Justin Smith ATV)
Ahhh, so they are different heights ! Sudbury`s two masts from a point exactly equidistant from both of them. The fact they`re bending inwards is obviously down to the wide angle
lens, not some new fangled engineering technology. The fact the picture is of low quality was down to the lighting conditions, but I`m not going all the way back just for one photo !
Above left we have Sudbury`s transmitting antennas from the West, and above right a
picture taken from the East, see close up of the latter below left.
Published Sudbury aerial heights
Analogue 1 to 4 = 136m
Analogue C5 = 96m
Digital = 118m
Digital (B) = 104m
a = analogue 1 to 4
b = analogue C5
c = digital (apart from MUX2 on CH68)
d = digital MUX2 on CH68
Study of the pictures will reveal that transmitters b and d cannot be omni-
Going by Ofcoms radiation pattern info it follows
that d would be for MUX2 (on CH68) and it is also
at approximately the right height, given that the mast`s total height is around 130m and the transmitting array should be at about 94m.
Transmitter b should be analogue C5 for which the aerial height is about 96m on a total mast height of 160m. I was particularly keen to confirm the radiation pattern for analogue C5 because the arrogant b******s wouldn`t tell me what it was.
I thought that b must be attenuated to the SW due
to its position on the mast. Also analogue C5 is on CH35 which is co-
is WSW) and Waltham C5, which is WNW. Furthermore there are two C5 repeaters W / SW
of Sudbury, Chelmsford on CH63 and Cambridge Madingley on CH34. If Sudbury C5 wasn`t attenuated to the SW why would these be
required ?
Chris Copping from Witham Satellites has revealed that C5 is attenuated to the SE
(for co-
tie in with Southerly restriction(s).
Close up of Sudbury`s digital transmitting array from the East. Note that the MUX2 transmitter (d) is “round the other side”.
Sudbury television transmitter`s frequencies/channels for before the DSO (above) and
for after it (below)
The frequencies given are for the analogue channels, for (most) digital MUXES add 3MHz.
Also check Sudbury`s five small repeater transmitters.
Note the gaps in the table below for channels 31 to 35, 37, 39 to 40 and 63 to 68, they`re reserved for “other uses”....
If you`ve found this site informative and, hopefully, interesting as well,
Sudbury`s channels in relation to the UHF TV band and the gain curves of the aerials
we recommend for it. DM Log Log40 Yagi18E DY14WB XB16E
Note the gain plot of the original B group of the transmitter and how certain MUXES are
out of band, and will continue be so after DSO in June 2011.
Also see other relevant E group curves.
For Sudbury we recommend the DM log for strong signal areas, the Log 40 for
medium signal areas, the Yagi18E or the DY14WB for poor signal areas,
and the XB16E for those with the most marginal signals.
The dimensions and test performance of the aerials can be found on the relevant tables.
If requiring a “high gain aerial” in the loft we recommend the DY14WB over the XB16 because of the former aerial`s smaller size.
For Sudbury`s TV Channels / Frequencies see its Channel Allocations for before and
after the DSO. These also include the same information for other potentially co-
Hertford, Hemel Hempstead, Oxford, Sandy, Waltham, Belmont and Tacolneston.
The Channel Allocation Guides can also be invaluable if you are trying to find a spare channel for a modulated output (e.g. for a Sky box or CCTV system) to be added to your
TV setup/distribution system without suffering from co-
Sudbury is due to remain an E group (or wideband) after DSO in June 2011,
though the 3 PSBs will still be within the original B group, see Sudbury`s graph.
MUXES 4 to 6 will be out of band though may be receivable in strong signal areas, particularly MUX4 on CH56.
Sudbury B will cease to transmit.
There are two interleaved spectrum channels allocated to Sudbury, CH49 and CH57, which
are both within the previously announced post DSO group.
The transmitter is about 2 miles East of the railway line from Marks Tey to Sudbury and
this was opened in 1849. Sudbury station has an interesting history as it was originally situated about 200yds further NW into Sudbury, but was moved when the line to Haverhill/Cambridge was opened by the Great Eastern Railway in 1865. Sadly this later addition closed in 1967.
External Links
Those situated to the West of Sudbury may find that during certain weather condition
they can suffer from co-