Simba27
Panthera leo massaieus
- Joined
- Aug 24, 2004
- Messages
- 150
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- My Satellite Setup
- Comag SL55 receiver. Lidl 0.6 LNB. Lidl 80cm dish. Metronic DiSEqC motor. Phillips Freeview box. JVC SVHS Video .Targa 160GB HDD/DVD recorder. 3 x UHF modulators. 6-way Booster/Splitter.
- My Location
- Uxbridge UK
[size=-1]www.ofcom.org.uk/static/archive/ ra/topics/research/rtcg/projects/project706.pdf[/size]
3.3 Practical Exercise to Assess Interference to Satellite TV (digital)
All three DUT’s were found to cause interference to the Sky digital satellite TV channels
that used frequencies within the band occupied by the DUT’s spurious emissions. These
included the free to air services such as BBC1 & 2, as well as the premium and pay-per-view
channels. The interference manifested itself as ‘blocking’ or ‘freezing’ of the
picture, and/or a loss of sound.
Interference was observed from 100% of the locations when the distance between the
DUT/vehicle and satellite dish was less than approximately 5 metres, and approximately
50% of the locations when the distance was increased to approximately 10 metres. Under
these conditions the maximum interference did not occur when the DUT/vehicle was
directly in front of the dish as might be expected, presumably because the main-lobe was
not directed at the DUT/vehicle whereas the dish’s side or back-lobes may have been.
Interference from random locations at distances of upto 20 metres was also observed,
often when the DUT was pointing away from the dish. This is believed to have been due
to back-scatter from a group of large trees under the main-lobe of the dish.
It should be noted that dish used was a 1 metre offset feed, and not the standard Sky
‘mini-dish’. The magnitude on the interference would, in practice, be expected to be
greater than that observed because; a) the level of the wanted satellite signal would be
lower with a ‘mini-dish’, anda ‘mini-dish’ would offer less rejection to ‘off-axis’
interference.
