On Topic: Latest 700 MHz plan

On 18/10/2016 13:41, Woody wrote:

I wouldn't have thought Bromsgrove/Lark Stoke/The Wrekin are exactly
'isolated' and they are a SFN.

Those three transmitters operate as an SFN only in the overlap
zones.

For instance Lark Stoke is not receivable in Telford. The network for
those three is designed so only in overlap areas, the signals combine
constructively. In other areas (for example Coventry) they combine
destructively, but that doesn't matter because of course SC is used.

It's like that because of a shortage in the West Midlands area of
frequencies.

I suspect many more examples of that after the 700 MHz switchover.

However, that' not what a national SFN network would be




--
Mark
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On 18/10/2016 19:18, Max Demian wrote:
On Tue, 18 Oct 2016 12:54:20 +0100, Mark Carver
wrote:
On 18/10/2016 11:37, tim... wrote:

As this issue with frequency allocation is only a problem when you
consider the way that they are allocated to avoid overlap at
transmitter
boundaries, it would be impossible to "test" in a small
geographic area.

Sorry, I wasn't clear. I was referring to just running at DTT mux
at 7
MHz rather than 7.8MHz.

Will that work with (any) existing receivers?

Probably would, and easy to quietly test in the field (After you've done
so with a collection of different examples in the lab)



--
Mark
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On Wed, 19 Oct 2016 09:30:46 +0100, Mark Carver
wrote:
On 18/10/2016 19:18, Max Demian wrote:
On Tue, 18 Oct 2016 12:54:20 +0100, Mark Carver
wrote:

Sorry, I wasn't clear. I was referring to just running at DTT
mux
at 7
MHz rather than 7.8MHz.

Will that work with (any) existing receivers?

Probably would, and easy to quietly test in the field (After you've
done
so with a collection of different examples in the lab)

If they're squeezing the multiplexes into narrower gaps, won't that
mean that they don't correspond to the old UHF channel numbers, which
current DTT receivers assume?

--
Max Demian

On 19/10/2016 13:46, Max Demian wrote:
On Wed, 19 Oct 2016 09:30:46 +0100, Mark Carver
wrote:
On 18/10/2016 19:18, Max Demian wrote:
On Tue, 18 Oct 2016 12:54:20 +0100, Mark Carver
wrote:

Sorry, I wasn't clear. I was referring to just running at DTT
mux
at 7
MHz rather than 7.8MHz.

Will that work with (any) existing receivers?

Probably would, and easy to quietly test in the field (After you've
done
so with a collection of different examples in the lab)

If they're squeezing the multiplexes into narrower gaps, won't that mean
that they don't correspond to the old UHF channel numbers, which current
DTT receivers assume?

In this context, the narrower muxes would be asymmetric around the
expected centre carrier frequencies, which is very 'non standard'

There is a centre frequency in a COFDM (aka DTT) but it only signifies
the middle of the 'grass lump'



--
Mark
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Max Demian wrote:

If they're squeezing the multiplexes into narrower gaps, won't that
mean that they don't correspond to the old UHF channel numbers, which
current DTT receivers assume?

Presume they just "silence" some of the carriers towards the edge(s) of
the channel?

"Andy Burns" wrote in message
...
Max Demian wrote:

If they're squeezing the multiplexes into narrower gaps, won't that
mean that they don't correspond to the old UHF channel numbers,
which
current DTT receivers assume?

Presume they just "silence" some of the carriers towards the edge(s)
of the channel?


No, it don't work like that. Mark will be along shortly to explain the
theory.




--
Woody

harrogate3 at ntlworld dot com

On 19/10/2016 03:37, Bill Wright wrote:
On 18/10/2016 13:05, Mark Carver wrote:

there are problems regarding the addition of further transmitters.
It's one reason why all DAB transmitters, even main ones, are relatively
low power)

Sorta defeats the object doesn't it?

SDL (aka D2) have applied a different idea for their mux. Only 45 sites
(compared with 400 for the Beeb (so far)). However some of the main
transmitters are 25kW. Wrotham and SC spring to mind.

That gives them wide general coverage, but will cause problems if/when
they decide to build gap fillers. Also, I lose reception of them, even
within sight of Hannington, at the slightest hint of a lift. BBC and D1
remain rock steady. In my case it's probably super powerful Wrotham
and/or SC causing destructive interference.

--
Mark
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On 19/10/2016 18:26, Woody wrote:
"Andy Burns" wrote in message
...
Max Demian wrote:

If they're squeezing the multiplexes into narrower gaps, won't that
mean that they don't correspond to the old UHF channel numbers,
which
current DTT receivers assume?

Presume they just "silence" some of the carriers towards the edge(s)
of the channel?


No, it don't work like that. Mark will be along shortly to explain the
theory.

The DVB-T spec allows for 5, 6, 7 or 8 MHz wide muxes. Presumably
they'd use the 7 MHz 'flavour', though something would have to give,
because the payload of the mux is a trade off against, channel b/w, FEC,
and GI, if they still wish to jam pack the muxes. Though at present COM
8 could take on excess from 7.


--
Mark
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Mark Carver wrote:

The DVB-T spec allows for 5, 6, 7 or 8 MHz wide muxes.

When the muxes had to co-exist with analogue channels there was the +/-
offsets from centre frequency, how far did the spec allow them to
"pushed" in either direction?

In message , tim...
writes

"Andy Burns" wrote in message
...
Max Demian wrote:

Mark Carver wrote:

https://www.ofcom.org.uk/__data/asse...9/Maximising-t
he-benefits-of-700-MHz-clearance-Statement.pdf

Could you summarise, please?

Less telly, more phones.

That they have to move the muxes, lose COM7 and 8 (presumably squashing
even more channels into the other 6 MUXes) by 2020 is a done deal.

Would that mean that the so-called "Freeview Lite" transmitters would
then be able to broadcast the full range of channels? Or is this thread
going completely over my head? :-)

--
Rab
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