700 MHz clearance: the shrinking TV band

TECHNICAL ANALYSIS
It appears Ofcom is intending to follow North America and the Asia Pacific region in clearing the 700 MHz frequency band for mobile broadband. This means that the frequencies available for traditional terrestrial television is to shrink even further.

So how is it changing? The following illustrates how the space available for terrestrial TV has been, and is changing. Updated 28/05/2014:

The UHF frequency band is broken into "channels", each consisting of a 8 MHz chunk of radio spectrum. In the beginning, the UHF frequency band was available for TV services. Services were broadcast between UHF channel 21 to 68, depending where you were in the UK. Channel 38 was set aside for Radio Astronomy.

  • In the tables below, UHF channel numbers in white or light orange cells are available for TV broadcasts The darker shaded cells indicate mobile broadband usage. UHF channel numbers used for other purposes are in shades of light blue.

Analogue TV wasted a lot of frequencies - only one TV channel could be broadcast on one UHF channel.

Then in 1998, low powered digital terrestrial television services started, using spare frequencies that could be used on a local basis that wouldn't interfere with analogue services. From then on, several TV channels could be broadcast on a data stream (multiplex) on one UHF channel.

Digital TV and Analogue TV shared the entire UHF frequency band from channel 21 to 68:


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26
27
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30
31
32
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35
36
37
38
39
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48
49
50
51
52
53
54
55
56
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58
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60
61
62
63
64
65
66
67
68


Switchover
As part of the switchover programme, two parts of the UHF band were to be cleared. As a consequence, the "600 MHz" band from UHF channel 31 was cleared. This includes the frequencies previously used by Channel 5 analogue in many parts of the UK (UHF channel 35 and 37). UHF channels 63 upward were also cleared, in early anticipation for more data demand.

21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
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47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68


2009-2018:
In 2009, it became clear that an international consensus was developing to clear the entire 800 MHz band - from UHF channel 61, not 63 upward. Ofcom then began to revise its switchover plans to clear UHF channels 61 and 62 as well as 63+. But as switchover was already well underway, and in some regions it would have been too complex to clear 61 and 62 due to neighbouring regions not having been switched yet, the clearance of these frequencies was held back until after switchover in numerous regions.

As a consequence, in many parts of the UK, services previously on UHF channels 61 and 62 were moved to channels 49 and 50. Services in 49 and 50 were moved down to 39 and 40 - part of the 600 MHz band cleared at switchover.

UHF channels 31-37 were initially not used after switchover.  In October 2013, UHF channel 33 was reactivated in London, testing a Freeview HD multiplex. From 26th November 2013 and until the 700 MHz band is cleared from 2019, Ofcom has permitted the use of UHF channels 31-37, except channel 36 for two Freeview HD multiplexes.

Channel 38's use changed from being reserved for Radio Astronomy to being reserved for "PMSE"use - e.g. wireless microphones. (see Ofcom page) PMSE was moved from UHF channel 69 as part of the 4G clearance process. 69 was not part of the TV band.

UHF Channel 36 has been used for a scientific propagation study.


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31
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35
36
37
38
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47
48
49
50
51
52
53
54
55
56
57
58
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60
61
62
63
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65
66
67
68


2019-2022:
Ofcom now wants to clear everything from UHF channel 49 upwards. This will reduce the available spectrum for TV and restrict it to UHF channels 21-48. However, UHF channels 31-37 will be reallocated to accommodate TV services, so in fact there will only be a loss of 5 UHF channels for TV use from 32 in late 2012 to 27 in 2022 and beyond.

UHF channel 38 remains reserved for other uses.

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48
49
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51
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68


2030?
From 2030, the whole of the UHF TV frequency band could be given up for mobile broadband use, heralding the end of free to air digital TV.


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49
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51
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63
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68


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