"Adrian" wrote in message
...
Hi Brian
Thanks for the reply...
On Mon, 16 Oct 2006 07:35:51 GMT, "Brian Sharrock"
wrote:
"Adrian" wrote in message
. ..
HI All
A tiny bit Off Topic - but if I can't get any joy out of the people
I've paid to do this job then I may end up DIY-ing it myself !
There was a discussion a few months back about the practicalities of
DIY setting up for a sky+ system out here in West Cork. General
consensus seemed to be that it wasn't such a difficult task - but, in
the end, time constraints cut in and I got a man in g
Result is that we have a little (oval - perhaps 80cm ?) sat dish up on
the gable end - with a clear view of the sky....
This is mostly OK (signal stength on channel 1 is about 50%, quality
about 25%, Stength on channel 2 is lower and quality doesn't even
indicate on the scale) - with a little 'stuttering' and picture
freezing from time to time.
The SKY+ box has two channels internally but are both fed off the one
aerial.
This aerial is actually a reflecting dish focussing the teeny-weeny signals
off the satellite onto a Quad LNB - the cables -from the SKY+ box are
sending a DC signal to the LNB's which sets up each exercised LNB
solid -state device to 'tune-into' the desired frequency and orientation of
the satellite's many signals.
Get a decent signal on Chanell 1, swap over the cables; the signal strength
should be exactly the same - it it isn't then you've got a faulty SKY+ box;
if they change then you've got a faulty Quad LNB. {Or faulty
cables/connectors }
When we have a heavy downpour the signal disappears altogether - which
means that the sky+ box gives up on any recordings that we're trying
to do.
Should we expect this situation (about the signal strength) - we're
out in the West of County Cork, near a little place called Ballydehob.
SKY , who now seem to broadcast to Irish consumers - judging from the
'Ireland' options when one 'presses the red button' - would be the
definitive expert on what signal strength they aniticipate at that Lat
Long.
{They will have a map of the satellite's broadcast 'footprint'}. however a
more practical approach may be to wander around your neighbourhood looking
out for 'dishes' on the south-east facades of houses and ask them what
their
experience is. 
Neighbours with dishes may say ' Our symptoms are precisely as yours! ' OR
'No, we get a perfect picture!' Either way you'll get a rapid response and
then now how to proceed.
Don't have many neighbours out here g - but I have asked a few
locals and they seem to be able to get acceptable reception.
So, if they can get it - so should you ! Complain to SKY!
AIUI, Channel 1 and 2 (off the quad LNB) are irrelevant as you may be
watching say Sky-One on Channel 1 or 2 so the signal strength should be
the
same! Channel 1 AUI is the defaul and feeds the recorder while Channel 2
becomes the alternate. You may have a dodgy Sky+ box and Channel 2's chain
is duff (to use a technical term). In UK Sky has a phone-line which will
offer advise.
It did seem a bit strange to me.
Maybe I'll swap the plugs from the wall to the sky-box and see if the
fault moves (nail through a cable, anybody ? g)
Might also take a look in the loft and see what sort of cable the
electrician installed - wonder if it's proper satellite stuff ?
I've a sneaking suspicion that the joins between the existing 'house'
cabling and the new dish were of the 'insulation tape & three Hail
Marys' variety - could be something odd going on there..?
The same 'expert installers' ( it says so on their van !) fitted an
aerial for Terrestrial Irish TV. We are about 5 miles direct line of
sight from the transmitter at Mount Gabriel - and getting a noticeably
snowy picture with some ghosting. The aerial is a 4 dipole + reflector
arrangement,
A TV aerial, properly called a Yagi Array, only has one proper dipole
(sometimes folded) this dipole is in fornt of the reflector and is where
the
signal is received. The other elements are properly called 'directors' and
contribute to received power by both adding to the signal [Gain] AND
making
the beam more narrow [Beam width] - requiring 'better' pointing.
Four dipoles plus reflector - three directors(?) doesn't seem at first
glance to be very directional - glancing out of my window at neighbouring
yagi arrays I count seven directors poiting at a transmitter in visual
range
on top of a hill perhaps six miles away.
Three directors might indicate a low gain wide beamwidth array.
Nope - I guess this is a form of 'curtain' array - four little
'bow-tie' elements sitting in front of a mesh reflector.
All 'fitted' in the loft by the expedient of nailing the reflector to
a roof-joist (!) - although the installer did use a signal-strength
meter to set it up....
............ that they've fitted in the loft (where it
has to look
through two concrete walls and is about 1ft from an enormous steel
'I-beam' which forms the ridge of the house. To compensate for this,
they've added a high-gain amplifier....
A high gain amplifier will increase the noise just as much as the signal
and
may swamp the input stages of your receivers. It's the wrong way round _
I'd
say an oirish way - but that's probably banned by some legislation or
other
; so I won't_.
You need to have a good signal off the dipole.
I thought as much - but thanks for confirming that I'm on the right
track...
To be fair - they did say that if we weren't happy then they'd come
back & fit the aerial outside...
It's _may_ not be the inide/outside aspectthat's wrong but the
GAIN/BEAMWIDTH that's incorrectly supplied. BTW, with direct line-of-sight
there's perhaps multiple paths for the signal to reach you You haven't
mentioned the juxtapositioning of the 'enormous' steel to the yagi; nor
the
orientation of the steel to the transmitter (aligned/broadside on/ skewed.
Perhaps the signal is bouncing off and your device is 'receiving' a
back-lobe?
The house is pretty much 'gable on' to the transmitter - so the aerial
is looking through the end gable wall, a small internal wall, and
'along' the line of the big metal beam. Plenty of room for relections
/ multiple signal paths there !
I haven't been able to sight "Ballydehob " on Google Earth's site!
'Ballydehob' isn't the Gaelic for "valley of no signal" is it?
So I don't know where abouts you are in relationship to Mount Gabriel -
{Truthfully; I don't now where that is either! Do you ever get trumpet
blasts?}
An Irish outfit that claims some expertise in terrestial Television - it
probalby says so on their vans :- recommends:-
NEW UHF TRANSMITTER ON AIR AT MOUNT
GABRIEL, CO CORK
RTE 1 NETWORK 2 TG4
Channel 29 Channel 33 Channel 23
For best reception for viewers, a UHF
Group A or broadband aerial should be
used.
For the east and south, aerials should
be horizontally polarised.
For the north and west, aerials should
be vertically polarised.
So - what should I expect in terms of satellite 'reliability' and
terrestrial picture quality?? - given that we are somewhat 'out in the
sticks - I don't want to be unreasonable with them, but I also don;'t
want to pay good euro for a 2nd-class job...
There are _no_ 'good euro' ....
There are when they are buying petrol at 2/3 the UK price over here !
g
Many thanks - I'll go investigate
Regards
Adrian
Advice appreciated - thanks in advance
Adrian
--
Brian