Andy Burns wrote:
Don Pearce wrote:

Most 3G is now at 1800MHz isn't it?

No, most 3G is 2100MHz, O2 have re-purposed some of their 900MHz
spectrum for 3G.

1800MHz was mostly Orange and T-Mobile (now EE) 2G (DCS), I think O2
and Vodafone had a small slice too, though EE have re-purposed some
as 4G and sold some to Three for the same.

Which is the 1710-1880MHz band

Why hasn't Ofcom flogged off 1850 -1990MHz which is used for
2g GSM in the USA?

My UK freq chart shows it as fixed and mobile

Steve Terry
--
Get a free GiffGaff PAYG Sim and £5 bonus after activation at:
http://giffgaff.com/orders/affiliate/gfourwwk

On Sat, 24 Nov 2012 15:37:15 GMT, (Don Pearce) wrote:

On Sat, 24 Nov 2012 15:25:23 +0000, lid wrote:

On Sat, 24 Nov 2012 14:47:25 GMT, (Don Pearce) wrote:

On Sat, 24 Nov 2012 14:30:18 +0000 (GMT), Jim Lesurf
wrote:


That may be so, but 1800 goes through windows easier than 800.

Curious. Why is that? Are the thicknesses/layers of double glazing a better
reflector at 800 than 1800?

You just reminded me - I was working for Marconi Electronics, and I
developed a 43GHz TV transmitter for MVDS (always too expensive). Our
windows were metallized inside and out for EMC screening as part of a
security measure. I was testing a link one day from the lab roof to my
office when I realised the window was closed, and it was still working
perfectly. Turned out the glass thickness was just about perfect for
constructive interference.


I'd be interested in any test results on 800 v 1800 MHz loss through
glass. Intuition suggests there would be little difference.

It isn't a question of glass loss so much as penetration of the
opening. Think of a car radio. When you drive into a tunnel, the long
wavelength of medium wave can't penetrate, and it stops dead. But the
short VHF wave of FM goes probably 100 yards into the tunnel.


I'm afraid I don't see the relevance of a tunnel to this.

A window into a room has open volumes on both sides, and signals can
approach from a wide range of angles. They don't have to approach at
90 degrees as they would have to do to travel down a tunnel, and there
is no waveguide effect.

At both 800 and 1800 MHz a wavelength is very small compared to most
window apertures, and even more so compared to the volume of the room
inside. As others have said the normal expectation is for the
attenuation due to glass to increase with frequency, and for both the
frequencies it will be quite small unless the glass has special
coatings.

Going up to 43GHz the wavelgth will be much closer to the thickness of
the glass or the spacing between glazing panels, and I could accept
that special effects might occur. But that is not the case for the
cellular radio bands.

In article , Don Pearce
scribeth thus
On Sat, 24 Nov 2012 14:30:18 +0000 (GMT), Jim Lesurf
wrote:


That may be so, but 1800 goes through windows easier than 800.

Curious. Why is that? Are the thicknesses/layers of double glazing a better
reflector at 800 than 1800?

You just reminded me - I was working for Marconi Electronics, and I
developed a 43GHz TV transmitter for MVDS (always too expensive). Our
windows were metallized inside and out for EMC screening as part of a
security measure. I was testing a link one day from the lab roof to my
office when I realised the window was closed, and it was still working
perfectly. Turned out the glass thickness was just about perfect for
constructive interference.

d

I know that some windows can clobber a Sky TV sat signals if they have
the right additives in them. If your needing to put an aerial inside for
various reasons...

And of course there are those railway carriages that do the same to
mobile phone signals.....
--
Tony Sayer

In article , Don Pearce
scribeth thus
On Sat, 24 Nov 2012 15:25:23 +0000, lid wrote:

On Sat, 24 Nov 2012 14:47:25 GMT, (Don Pearce) wrote:

On Sat, 24 Nov 2012 14:30:18 +0000 (GMT), Jim Lesurf
wrote:


That may be so, but 1800 goes through windows easier than 800.

Curious. Why is that? Are the thicknesses/layers of double glazing a better
reflector at 800 than 1800?

You just reminded me - I was working for Marconi Electronics, and I
developed a 43GHz TV transmitter for MVDS (always too expensive). Our
windows were metallized inside and out for EMC screening as part of a
security measure. I was testing a link one day from the lab roof to my
office when I realised the window was closed, and it was still working
perfectly. Turned out the glass thickness was just about perfect for
constructive interference.


I'd be interested in any test results on 800 v 1800 MHz loss through
glass. Intuition suggests there would be little difference.

It isn't a question of glass loss so much as penetration of the
opening. Think of a car radio. When you drive into a tunnel, the long
wavelength of medium wave can't penetrate, and it stops dead. But the
short VHF wave of FM goes probably 100 yards into the tunnel.

d

And more often than not these days has a leaky feeder repeater system
installed from almost DC to daylight;!...
--
Tony Sayer

On Sat, 24 Nov 2012 18:27:48 +0000, lid wrote:

On Sat, 24 Nov 2012 15:37:15 GMT, (Don Pearce) wrote:

On Sat, 24 Nov 2012 15:25:23 +0000, lid wrote:

On Sat, 24 Nov 2012 14:47:25 GMT, (Don Pearce) wrote:

On Sat, 24 Nov 2012 14:30:18 +0000 (GMT), Jim Lesurf
wrote:


That may be so, but 1800 goes through windows easier than 800.

Curious. Why is that? Are the thicknesses/layers of double glazing a better
reflector at 800 than 1800?

You just reminded me - I was working for Marconi Electronics, and I
developed a 43GHz TV transmitter for MVDS (always too expensive). Our
windows were metallized inside and out for EMC screening as part of a
security measure. I was testing a link one day from the lab roof to my
office when I realised the window was closed, and it was still working
perfectly. Turned out the glass thickness was just about perfect for
constructive interference.


I'd be interested in any test results on 800 v 1800 MHz loss through
glass. Intuition suggests there would be little difference.

It isn't a question of glass loss so much as penetration of the
opening. Think of a car radio. When you drive into a tunnel, the long
wavelength of medium wave can't penetrate, and it stops dead. But the
short VHF wave of FM goes probably 100 yards into the tunnel.


I'm afraid I don't see the relevance of a tunnel to this.

A window into a room has open volumes on both sides, and signals can
approach from a wide range of angles. They don't have to approach at
90 degrees as they would have to do to travel down a tunnel, and there
is no waveguide effect.

At both 800 and 1800 MHz a wavelength is very small compared to most
window apertures, and even more so compared to the volume of the room
inside. As others have said the normal expectation is for the
attenuation due to glass to increase with frequency, and for both the
frequencies it will be quite small unless the glass has special
coatings.

Going up to 43GHz the wavelgth will be much closer to the thickness of
the glass or the spacing between glazing panels, and I could accept
that special effects might occur. But that is not the case for the
cellular radio bands.

You are right. I carried the analogy way too far. The general
principle holds though - slightly.

d

On Sat, 24 Nov 2012 19:29:24 +0000, tony sayer
wrote:

In article , Don Pearce
scribeth thus
On Sat, 24 Nov 2012 15:25:23 +0000, lid wrote:

On Sat, 24 Nov 2012 14:47:25 GMT, (Don Pearce) wrote:

On Sat, 24 Nov 2012 14:30:18 +0000 (GMT), Jim Lesurf
wrote:


That may be so, but 1800 goes through windows easier than 800.

Curious. Why is that? Are the thicknesses/layers of double glazing a better
reflector at 800 than 1800?

You just reminded me - I was working for Marconi Electronics, and I
developed a 43GHz TV transmitter for MVDS (always too expensive). Our
windows were metallized inside and out for EMC screening as part of a
security measure. I was testing a link one day from the lab roof to my
office when I realised the window was closed, and it was still working
perfectly. Turned out the glass thickness was just about perfect for
constructive interference.


I'd be interested in any test results on 800 v 1800 MHz loss through
glass. Intuition suggests there would be little difference.

It isn't a question of glass loss so much as penetration of the
opening. Think of a car radio. When you drive into a tunnel, the long
wavelength of medium wave can't penetrate, and it stops dead. But the
short VHF wave of FM goes probably 100 yards into the tunnel.

d

And more often than not these days has a leaky feeder repeater system
installed from almost DC to daylight;!...

The one in the Hatfield tunnel is selective. Only a couple of stations
are on it.

d

Jim Lesurf wrote:

One of the main uncertainties at present is how 4G will be deployed.
We know the timetable for DTTV clearance, and the specs on offer for
the 4G bids. But not where and when the 4G base stations will become
active. So I guess most people will have no idea - until their TV screen
goes blank one day.

The whole point here is that the base stations will be turned on over a
longish period of time. A few people losing their reception is not a
news story. Thus there will be no outcry.

Bill

In article , Bill Wright
wrote:
Jim Lesurf wrote:

One of the main uncertainties at present is how 4G will be deployed.
We know the timetable for DTTV clearance, and the specs on offer for
the 4G bids. But not where and when the 4G base stations will become
active. So I guess most people will have no idea - until their TV
screen goes blank one day.

The whole point here is that the base stations will be turned on over a
longish period of time. A few people losing their reception is not a
news story. Thus there will be no outcry.

I guess OfCom know how to boil a frog.

BTW I was told yesterday that there was a critical item about this topic in
The Granuoad last Saturday. Anyone see it? I'm not fit enough to carry such
a large newspaper home from the shop!

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
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Jim Lesurf wrote:

BTW I was told yesterday that there was a critical item about this topic in
The Granuoad last Saturday. Anyone see it? I'm not fit enough to carry such
a large newspaper home from the shop!

The internet is your friend :-)

http://www.guardian.co.uk/technology/2012/nov/16/tvs-retuning-room-mobile-services?INTCMP=SRCH


--
Mark
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www.paras.org.uk

Don Pearce wrote:

And more often than not these days has a leaky feeder repeater system
installed from almost DC to daylight;!...

The one in the Hatfield tunnel is selective. Only a couple of stations
are on it.

Which ones, I've never found anything that is ?

Anyone know how the mobile phone service in the Channel Tunnel is engineered ?

Only seems to work on the UK-bound bore, but all three of the French networks
are there, all with 3G. Signal lasts as far as the UK tunnel exit.

Nothing going the other way, presumably VF, O2, and/or EE have been invited to
provide a service ?


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

www.paras.org.uk