19-08-2019, 09:52 PM
European VHF frequency planning was done at the ITU 1952 Stockholm meeting (ST52). However, there were many subsequent changes, as some participating countries submitted only provisional plans that were quite different to what was actually adopted post-ST52. A small part of that comes out in this current VRAT thread: https://www.radios-tv.co.uk/community/bl...post-97389. The UK was a participant at this meeting.
The ITU 1961 Stockholm meeting (ST61) was mostly about European UHF frequency planning, but at the same time the VHF assignments were updated.
According to the attached WW 1953 August article, Tacolneston was originally planned as using channel 6. But the BBC was denied access to Band III at the time, and had to rework its national coverage plan to use only the Band I channels. The net result was that Band I was oversubscribed, and Band III was underutilized. The BBC required noticeably more Band I transmitters (and eventually a small number in Band III) to achieve national coverage than did the ITA using Band III alone. Given that Band I signals generally travel further than those in Band III, one might expect it to have been the other way around. But with the overstuffing, the Band I distance capability was a liability. Second-level transmitters needed to have carefully controlled erps and directionalities so as not to interfere with the main transmitters, and that resulted in coverage gaps as compared with what might have been possible had clear or reasonably clear channels been available. So infill transmitters were required and so it went on.
Three-element Yagis were I think the most common TV aerials around Auckland, NZ in the 1960s. Small arrays were much less common, less seen than larger types, such as 4-element. Channel NZ2 was 54-61 MHz (the same as E3), and not too much different to B3 (53-58 MHz). But our Yagis all had folded dipoles, which made them more rigid mechanically, although the reflectors and directors sometimes suffered from end-droop. The latter was much more visible in Wellington, where channel NZ1 (44-51 MHz) was used, requiring noticeably longer aerial elements; wind damage was also a major problem.
Cheers,
Steve
The ITU 1961 Stockholm meeting (ST61) was mostly about European UHF frequency planning, but at the same time the VHF assignments were updated.
According to the attached WW 1953 August article, Tacolneston was originally planned as using channel 6. But the BBC was denied access to Band III at the time, and had to rework its national coverage plan to use only the Band I channels. The net result was that Band I was oversubscribed, and Band III was underutilized. The BBC required noticeably more Band I transmitters (and eventually a small number in Band III) to achieve national coverage than did the ITA using Band III alone. Given that Band I signals generally travel further than those in Band III, one might expect it to have been the other way around. But with the overstuffing, the Band I distance capability was a liability. Second-level transmitters needed to have carefully controlled erps and directionalities so as not to interfere with the main transmitters, and that resulted in coverage gaps as compared with what might have been possible had clear or reasonably clear channels been available. So infill transmitters were required and so it went on.
Three-element Yagis were I think the most common TV aerials around Auckland, NZ in the 1960s. Small arrays were much less common, less seen than larger types, such as 4-element. Channel NZ2 was 54-61 MHz (the same as E3), and not too much different to B3 (53-58 MHz). But our Yagis all had folded dipoles, which made them more rigid mechanically, although the reflectors and directors sometimes suffered from end-droop. The latter was much more visible in Wellington, where channel NZ1 (44-51 MHz) was used, requiring noticeably longer aerial elements; wind damage was also a major problem.
Cheers,
Steve
