earn valley aerials digital tv & radio reception solutions
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site last updated 18th Aug. 2017
Don't start adding filters and changing masthead amplifiers without giving the aerial a cursory glance at the very least. A bit of aerial work can pay dividends here both technically and financially, the latter because customers seem to see more value in shiny things on the chimney than in boxes in the loft or your time.The fundamental principle is to improve the ratio between the wanted and unwanted transmissions as much as possible. Firstly, I'll state the obvious. The aerial should be pointing accurately at the TV transmitter, and it should be sited as advantageously as possible. If raising the aerial or moving it to the other chimney gives it better line-
TV aerials designed to work right down to the bottom of the UHF TV band (470MHz) seem to work surprisingly well on 400MHz, even exhibiting some directional properties and gain! If possible avoid the use of wideband aerials. These are often installed unnecessarily these days, thanks largely to the widespread misinformation that DTT always needs one. If all the analogue and digital TV signals are in Group B or C/D, the low frequency response of a wideband aerial is merely contributing troublesome interference such as TETRA. The performance deficit of wideband-
As a desperate last resort, it might be possible to improve the signal to interference ratio by re-
Aerials for VHF FM should be fixed with horizontal polarisation, assuming that the transmissions include a horizontal component, as most do. Unfortunately DAB aerials have to be fixed vertically.
Tetra mast, Worthing
Over the years the electromagnetic spectrum has become ever more crowded. During my time as an aerial installer I have seen all sorts of innovations that that can cause problems for UHF TV reception. In the late 70s and early 80s there was the CB craze. Then we had the illegal high-
Over the years, ensuring good EMC performance has become an important part of the installer's work. TETRA is no more than the latest challenge. I'm sure it won't be the last!
Tetra interference continued…