Goodbye 700MHz (aka UHF Ch 48-60)

"Stephen" wrote in message
...
On 20/11/2014 09:18, Mark Carver wrote:
On 20/11/2014 09:10, Brian Gaff wrote:
One thing that puzzles me is that there seem to be huge areas of vhf
not
being used much nowadays, and although I realise the longer wavelength
might
be a problem for the aerials, why don't mobile systems use those.

How efficient would a VHF aerial inside a mobile phone be ?


it would be impractical, as lower frequency means longer wavelength and
hence a bigger aerial.

I think there is a lower limit to a usuable frequency given a phone's
physical size.... After all who wants a FM aerial in their pocket?

Years ago my partner had a Motorola phone with an FM radio.

Worked pretty well. Not sure what the aerial arrangement was, tend not to
worry to much about stuff if it works!

James

On Thursday, November 20, 2014 9:54:00 PM UTC, James Heaton wrote:
"Stephen" wrote in message
...
On 20/11/2014 09:18, Mark Carver wrote:
On 20/11/2014 09:10, Brian Gaff wrote:
One thing that puzzles me is that there seem to be huge areas of vhf
not
being used much nowadays, and although I realise the longer wavelength
might
be a problem for the aerials, why don't mobile systems use those.

How efficient would a VHF aerial inside a mobile phone be ?


it would be impractical, as lower frequency means longer wavelength and
hence a bigger aerial.

I think there is a lower limit to a usuable frequency given a phone's
physical size.... After all who wants a FM aerial in their pocket?

Years ago my partner had a Motorola phone with an FM radio.

Worked pretty well. Not sure what the aerial arrangement was, tend not to
worry to much about stuff if it works!

James

Usually the headphone lead forms the FM antenna.

On Thu, 20 Nov 2014 19:57:35 +0000, Graham. wrote:

On Thu, 20 Nov 2014 19:30:44 +0000, Peter Duncanson
wrote:

On Thu, 20 Nov 2014 19:20:18 +0000, Stephen
wrote:



It's a shame that you can't split a satellite feed in the way that you
can split a TV aerial feed (assuming your signal is strong enough) if
you need to drive an extra device; instead you need an additional LNB
and an extra down-lead.


It can be "split" but you do need to swap the LNB for a Quattro LNB and
then buy a multiswitch. Ther are available with up to 32 outputs and
cascadeable versions are available if you *really* need more than 32
outputs from one dish.

There are apparently some Quad LNBs that can be used with a multiswitch.

I think it is more accurate to say that there are some multiswitches
that can use a quad LNB. They just have to output the reinvent voltage
and 22 kHz tone to the appropriate inputs.

I seem to have got that back to front. My mistake.

--
Peter Duncanson
(in uk.tech.digital-tv)

In message , PeterC
writes
On Wed, 19 Nov 2014 21:49:20 -0000, Robin wrote:

It's the beginning of the end for DTT IMHO

and so is also the beginning of a potential path to switch BBC funding
from licence fee to subscription?

The new series of Atlantis is now 45 min. per episode - 15 min. of breaks?

That's generous, they're usually 42 mins.
--
Ian

In message , James Heaton
writes

"Stephen" wrote in message
...
On 20/11/2014 09:18, Mark Carver wrote:
On 20/11/2014 09:10, Brian Gaff wrote:
One thing that puzzles me is that there seem to be huge areas of
vhf not
being used much nowadays, and although I realise the longer wavelength
might
be a problem for the aerials, why don't mobile systems use those.

How efficient would a VHF aerial inside a mobile phone be ?


it would be impractical, as lower frequency means longer wavelength
and hence a bigger aerial.

I think there is a lower limit to a usuable frequency given a phone's
physical size.... After all who wants a FM aerial in their pocket?

Years ago my partner had a Motorola phone with an FM radio.

Worked pretty well. Not sure what the aerial arrangement was, tend not
to worry to much about stuff if it works!

James

The headphones double as an aerial.
--
Ian

On Thu, 20 Nov 2014 20:13:44 +0000, Graham. wrote:

On Thu, 20 Nov 2014 19:17:07 +0000, Stephen
wrote:

On 20/11/2014 09:18, Mark Carver wrote:
On 20/11/2014 09:10, Brian Gaff wrote:
One thing that puzzles me is that there seem to be huge areas of vhf not
being used much nowadays, and although I realise the longer wavelength
might
be a problem for the aerials, why don't mobile systems use those.

How efficient would a VHF aerial inside a mobile phone be ?


it would be impractical, as lower frequency means longer wavelength and
hence a bigger aerial.

I think there is a lower limit to a usuable frequency given a phone's
physical size.... After all who wants a FM aerial in their pocket?

My first two mobiles both had pull-up aerials. Then, as phones became
fashion accessories, aerials became unpopular. They must have taken a
performance hit, especially at 900Mhz.

I rather doubt that was the case (1/4 wavelength at 900 MHz is about
8cm). Motorola probably thought it best to create a cardiod pattern
antenna array using the body of the phone to place the null right
where the users' heads would be (no point in wasting a good third of
all that hard won RF power microwaving the customers's heads).

Motorola by any chance?

http://www.cntr.salford.ac.uk/comms/25yrsofthemobile/survey.php

Number 9 - Motorola MicroTAC

With 4.7% of the total votes cast, we have the Motorola MicroTAC.
Launched in 1989 this phone was truly revolutionary not only because
of its size but also because of its flip design. Mobiles could now be
genuinely carried with you. The Motorola MicroTAC was the world's
first flip mobile. Here a moveable plate opens to reveal the keypad
and provide a mouthpiece to talk into. However, although people though
that the flip plate contained the microphone, in fact it didn't.


Equally, the extendable aerial was also fake, being simple a piece of
aerial shaped plastic. This latter feature was included because market
research had told the Motorola designers that users expected mobiles
to have external aerials! The MicroTAC had both an internal microphone
and aerial.
--
J B Good

On Thu, 20 Nov 2014 11:19:29 -0000, NY wrote:

It's a shame that you can't split a satellite feed in the way that you can
split a TV aerial feed (assuming your signal is strong enough) if you need
to drive an extra device; instead you need an additional LNB and an extra
down-lead.

No you don't. You install 4 cables from a quattro LNB to a multiswitch
instead of 4 cables from a quad LNB to wherever.
Then you can have any number of feeds to wherever from the multiswitch,
assuming you get the correct sized multiswitch.

Steve Thackery wrote:
Scott wrote:

Given
that digital is 'all or nothing'

Why do people keep saying that? It simply isn't true. I lived for
years on a marginal reception area for DTTV, and instead of picture
noise on analogue, we got pixellation and freezes, which occured more
or less often depending on the weather. Sometimes it was unwatchable,
other times it was fine.

Certainly not "all or nothing".

The change in signal level necessary to go from perfect digital
reception to no reception is much less than the change necessary to go
from perfect analogue reception to no reception. But yes, there is a
narrow band of signal levels in which digital will give unreliable
reception. That's why silly little things can seem to make such a
difference when digital reception is just 'on the cusp'.

Bill

lid wrote:

And at each retune, another cohort of DTT viewers slip away to
satellite or cable. Thus making DTT less viable and bringing forward
the next spectrum handover.

Job done!

And when the aerial falls over people tend to migrate to satellite or
internet, rather than get a new aerial.

Bill

Woody wrote:
"Mark Carver" wrote in message
...
On 20/11/2014 18:27, Scott wrote:

I wondered about multipath. Could the relays simply be
put on the
same channel as the main transmitter - or is there more
to it than
that?
They wouldn't be able to use their usual off air feed
(that all but
80 of the 1000 or so relays use) so they'd need to be
either fibre or microwave fed (very expensive, if not
impossible for some) And then
they'd effectively operate in an SFN, which, well, see my
previous comments about that.




Er, what about satellite feeds - as already used?


Would synchronisation be a problem?

Bill