Horizontal only?

Analogue signals used to be either horizontally or vertically polarised but
I've only ever seen reference to digital transmissions being horizontally
polarised. Is this correct or can they be vertical as well (it's important
to me as I travel all over the country by narrowboat)

--
Allan Jones - N/B 'Keeping Up'
www.keeping-up.co.uk

In article ,
Allan Jones wrote:
Analogue signals used to be either horizontally or vertically polarised
but I've only ever seen reference to digital transmissions being
horizontally polarised. Is this correct or can they be vertical as well
(it's important to me as I travel all over the country by narrowboat)

They can be polarised either way. Initially only 49 main (horizontally
polarized) transmitters have been converted to send out digital signals as
well as analogue ones. The relays stations (another 1000+) will be
converted to carry digital signals instead of the analogue ones. The relay
at Whitehaven was the first (2 months ago), other will follow over the next
5 years.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11

Allan Jones wrote:
Analogue signals used to be either horizontally or vertically polarised
but I've only ever seen reference to digital transmissions being
horizontally polarised. Is this correct or can they be vertical as well
(it's important to me as I travel all over the country by narrowboat)

The polarisation used by DTT employs the same polarisation of the analogue
transmissions from a given site. About 35 of the current 85 DTT equipped
transmitters are vertically polarised.

However most of the 1100 or so low power relay stations that use vertical polz
have yet to be enabled for DTT.

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

"Allan Jones" wrote in message
...
Analogue signals used to be either horizontally or vertically polarised
but I've only ever seen reference to digital transmissions being
horizontally polarised. Is this correct or can they be vertical as well
(it's important to me as I travel all over the country by narrowboat)

There are quite a number of vertically polarised digital transmitters.

http://www.dtg.org.uk/retailer/transmitters.html

shows all the present transmitters by region. The polarisation is in the
'aerial group' column.

Vertical is usually only used for relay transmitters, most of which are yet
to go digital.

This poses an interesting question though.

Before, when the UHF services were all going off vhf, the sites of the
relays were mostly there for bbc 2 already.

In this case will we have a situation where those on the main transmitters
switch over, but the relays still show analogue? This sort of thing
definitely happened in the 1969 switch over, but as sets were dual standard
it mattered little then. Now it could be a problem.

Brian

--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
__________________________________________________ __________________________________________________ __________


"Albert" wrote in message ...
"Allan Jones" wrote in message
...
Analogue signals used to be either horizontally or vertically polarised
but I've only ever seen reference to digital transmissions being
horizontally polarised. Is this correct or can they be vertical as well
(it's important to me as I travel all over the country by narrowboat)

There are quite a number of vertically polarised digital transmitters.

http://www.dtg.org.uk/retailer/transmitters.html

shows all the present transmitters by region. The polarisation is in the
'aerial group' column.

Vertical is usually only used for relay transmitters, most of which are
yet to go digital.

On Dec 11, 9:44 am, "Brian Gaff" wrote:
This poses an interesting question though.

Before, when the UHF services were all going off vhf, the sites of the
relays were mostly there for bbc 2 already.

In this case will we have a situation where those on the main transmitters
switch over, but the relays still show analogue? This sort of thing
definitely happened in the 1969 switch over, but as sets were dual standard
it mattered little then. Now it could be a problem.

I'm not sure what you mean. When each main transmitter has its
analogue channels finally switched off on DSO night, the DTT
transmissions will be raised in power, and all of that main station's
associated relay stations will also transmit DTT (for the first time
in most cases). Analogue transmissions from those relays will cease
at the same time.

"Mark Carver" wrote in message
...
In this case will we have a situation where those on the main
transmitters
switch over, but the relays still show analogue? This sort of thing
definitely happened in the 1969 switch over, but as sets were dual
standard
it mattered little then. Now it could be a problem.

I'm not sure what you mean. When each main transmitter has its
analogue channels finally switched off on DSO night, the DTT
transmissions will be raised in power, and all of that main station's
associated relay stations will also transmit DTT (for the first time
in most cases). Analogue transmissions from those relays will cease
at the same time.
I wonder how many relays will be declared 'unviable'.

Bill

On Tue, 11 Dec 2007 10:20:29 -0000, "Bill Wright"
wrote:


"Mark Carver" wrote in message
...
In this case will we have a situation where those on the main
transmitters
switch over, but the relays still show analogue? This sort of thing
definitely happened in the 1969 switch over, but as sets were dual
standard
it mattered little then. Now it could be a problem.

I'm not sure what you mean. When each main transmitter has its
analogue channels finally switched off on DSO night, the DTT
transmissions will be raised in power, and all of that main station's
associated relay stations will also transmit DTT (for the first time
in most cases). Analogue transmissions from those relays will cease
at the same time.
I wonder how many relays will be declared 'unviable'.

Bill

I would imagine that some relays are only in place due to multipath
problems rather than weak signals, so these relays may not be required
for DTT. But switching those off would involve moving aerials or even
replacing aerials which I'm sure wouldn't be welcomed by most
residents.

Marky P.

"Marky P" wrote in message
...
On Tue, 11 Dec 2007 10:20:29 -0000, "Bill Wright"
wrote:

I would imagine that some relays are only in place due to multipath
problems rather than weak signals,
Very few, really. But this will be the excuse I expect for thinning out the
relays.

so these relays may not be required
for DTT. But switching those off would involve moving aerials or even
replacing aerials which I'm sure wouldn't be welcomed by most
residents.
The powers that be won't worry too much about that. Sandsend has shown what
their true colours are.

Bill

In article
.co.uk.invalid,
Alan Pemberton wrote:
Brian Gaff wrote:

In this case will we have a situation where those on the main
transmitters switch over, but the relays still show analogue? This
sort of thing definitely happened in the 1969 switch over, but as
sets were dual standard it mattered little then. Now it could be a
problem.

No, that cannot have been the case because (unless Charles knows
differently) all 405-line relays received their signals off-air from the
parent station.

Charles agrees with you on that although I think there were one or two
relays of relays. I would also point out that 1969, the date mentioned by
the OP, was the start of uhf for BBC1 & ITV, not any switch over. Dual
standard sets were, in general, needed to watch BBC2 when the other two
services had not arrived on uhf. I'm pretty sure that by 1973, when I
started with EID, all uhf transmitter had 3 services and, in general all 3
services started simultaneously. Exceptions, that I can remember, were
Eitshal (BBC services 2 or 3 months before ITV) and Arfon (ITV only for a
few months).

The 405-line closure was handled differently from this
625-line one. By 1983 (when the first stations were shut down) a
parallel service had been in operation for up to fourteen years in some
areas. In general the newest main stations and relays were turned off
first, followed by all the remaining stations in January 1985.

The problem this time is that the new services have to use the same
spectrum space (allocated differently in each area) as the old services.

--
From KT24 - in "Leafy Surrey"

Using a RISC OS computer running v5.11