Sutton Coldfield DTT

"Mark Carver" wrote in message
...
Bill Wright wrote:
While I'm not silly enough to expect predicable performance out of band,
is the roll off on lower gain aerials generally not as steep as with high
gain ?

I don't know. However, in time-honoured newsgroup tradition I will make
something up to fill the gap (1). In general I don't see why the roll off
should be more because a high gain aerial won't be more narrowly tuned than
a low gain one. Of course the 'starting point' will be higher so in that
sense . . . yes, I suppose . . .

In general yagis drop off very quickly above their design range; less
quickly below it. This is one reason why TETRA can be a problem. A Gp A
aerial (470 to 600MHz) vertically polarised and looking at a relay that is
co-sited with the TETRA mast will pick up uncomfortably large amounts of
390ish MHZ TETRA. It will even demonstrate vaguely rational directional
characteristics.

(1) Inventing facts to fill a void in knowledge is a human characteristic
that also explains Ancient Greek medicine and all religion.

Theory suggests a yagi is always a compromise between gain and bandwidth,
what's your practical experience Bill ?
Yes it is. Hence my recent experiments with narrow band aerials for parts of
the FM band, as described in these pages on a previous occasion (if anyone's
interested in this I'll dig it out). Hence also
http://www.wrightsaerials.tv/aerialp...odern/006.html


Bill

"Mark Carver" wrote in message
...
Doctor D wrote:

Sorry I don't know anyone in that area, however using a generic central
Leamington Spa postcode gives this variable result :
http://www.digitaluk.co.uk/postcodec...038c1fd7591742

Good thinking, I'd forgotten about that. Looks better than that chucking
their postcode in:-

http://www.markyboy.net/lemspa.jpg

As an aside, I'm now using group B's on SC with little if any noticeable
loss in performance on 55. I suspect new ones have slightly better gain
at the ends of group B, also I don't use contract aerials.

Something I seem to recall from several years in here, is that many Sutton
Coldfield folk get away with Group Bs for the Ch 55 mux ?

They almost always do. The power is a bit higher though, and there isn't the
CCI from Emley analogue which causes a lot of probs in some areas.

Bill

In an earlier contribution to this discussion,
Mark Carver wrote:

I was in Leamington Spa yesterday visiting relations who have just
moved there.
They're in a Victorian terraced house, with three floors and a
chimney a scary height above the ground !

Two aerials, one an 18 element, non contract type, another a 10
element contract slightly lower down. Both have feeders coming down
from roof flapping in the wind, one has an indoor splitter wrapped up
in insulation tape that feeds two rooms. It all needs ripping out,
and starting again. However as a quick fix to tide them over, I'm
planning to replace the 'reachable' parts of the installation with
new cable, and a Proception active 2 way spitter fed from the
contract. The 18 element will become redundant (in fact it is currently).

Both aerials supply very good analogue pictures for the main four. The
contract aerial additionally supplies a good C5 analogue picture from
Lichfield. Neither can receive anything from Mux D (Ch 55 so just out
of band for a Grp B) and the contract struggles a little with Mux C
(Ch 52) and Mux 1 (Ch 41).

Could be lots of reasons, water in the coax, the indoor spitter that's
outdoors might have rotted away, mismatches everywhere.......

One question before I waste any of their money, and my time. Does
anyone have experience of reception of Sutton Coldfield in that area
? I want to make sure that Muxes C and D are beamed that way with the
same whack as the other four muxes.

I live just the other side of Warwick from Leamington, in a potentially
worse reception area 'cos we're in the shadow of Hatton Hill. Nevertheless,
I get *reasonable* reception from all 6 SC muxes using a Gp B aerial - so
the same should also be true in Leamington, I would have thought.

I also get pretty good CH5 analog reception from Litchfield - whose
direction from my house is only a couple of degrees different from SC.

There is, of course, a Leamington Spa relay - located on the Campion Hills -
but I can't find any evidence that it currently transmits any digital, so
maybe it won't until after switch-over. It's pretty low power anyway - but
does serve some parts of Leamington - but maybe only with analog signals, in
which case it won't help you at the moment. But it may be worth checking out
in case I'm missing something.
--
Cheers,
Roger
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Roger Mills wrote:

[snip]

There is, of course, a Leamington Spa relay - located on the Campion Hills -
but I can't find any evidence that it currently transmits any digital, so
maybe it won't until after switch-over. It's pretty low power anyway - but
does serve some parts of Leamington - but maybe only with analog signals, in
which case it won't help you at the moment. But it may be worth checking out
in case I'm missing something.

Thanks Roger.

Yes, I'm aware of the Leamington relay. It's line of sight, and only about a
mile away from the house. Provides a smashing analogue signal, but as you
suspect no DTT until DSO in Sept 2011. It does transmit BBC 1 analogue on UHF
Ch 56, so I am mindful it might be splashing across onto Mux D/Ch 55 from
Sutton and not helping the situation.

--
Mark
Please replace invalid and invalid with gmx and net to reply.

In an earlier contribution to this discussion,
Mark Carver wrote:


Yes, I'm aware of the Leamington relay. It's line of sight, and only
about a mile away from the house. Provides a smashing analogue
signal, but as you suspect no DTT until DSO in Sept 2011. It does
transmit BBC 1 analogue on UHF Ch 56, so I am mindful it might be
splashing across onto Mux D/Ch 55 from Sutton and not helping the
situation.

I think it's vertically polarised though, so you shouldn't pick up much on
your Sutton aerial.
--
Cheers,
Roger
______
Email address maintained for newsgroup use only, and not regularly
monitored.. Messages sent to it may not be read for several weeks.
PLEASE REPLY TO NEWSGROUP!

Roger Mills wrote:
In an earlier contribution to this discussion,
Mark Carver wrote:

Yes, I'm aware of the Leamington relay. It's line of sight, and only
about a mile away from the house. Provides a smashing analogue
signal, but as you suspect no DTT until DSO in Sept 2011. It does
transmit BBC 1 analogue on UHF Ch 56, so I am mindful it might be
splashing across onto Mux D/Ch 55 from Sutton and not helping the
situation.

I think it's vertically polarised though, so you shouldn't pick up much on
your Sutton aerial.

Oh it did ! There's was loads of signal, full of ghosting of course. Also had
quite strong signals from the Lark Stoke relay, but covered in co-channel
interference from The Wrekin (or possibly vice versa !).

--
Mark
Please replace invalid and invalid with gmx and net to reply.