Mendip re-tune

Jim Lesurf wrote:

Count up the number of main stations/high powered relays, average the
ERPs, deduct aerial gain.

Alas, the 'aerial gain' varies both from TX to TX and with direction. But I
assume you knew that, as well. :-)
The max ERP would be good enough.

Bill

On 16/03/2012 12:15, Jim Lesurf wrote:
In , Java Jive
wrote:
On Fri, 16 Mar 2012 09:01:25 +0000 (GMT), Jim Lesurf
wrote:

IIRC OfCom provide an Excel sheet of the ERPs and antenna permitted
envelopes, etc.

I don't know if it's the one of which you are thinking, but I have
something called ... Antenna_filenames_and_site_numbers_060809.xls ...
which I must have downloaded some time ago from Ofcom or elsewhere. A
search just now for the file name didn't find it.

Alas, I've just checked what I have. I do have full XLS sheets for DAB and
VHF (i.e. sound radio) that give the antenna pattern envelopes, etc. But I
now remember that when I asked OfCom for equivalent data for DTTV I was
told they didn't have it available!

Afraid I'd mis-remembered which data set I'd been unable to get. I seem to
recall that many years ago I had no trouble getting the analog TV TX data
from the old Radcom Agency. But then they did have a clue about
engineering. Talking to someone I know a few days ago who is ex-Radcom and
his view also is that they dumped all the engineers when the RA was eaten
by OfCom suits. Although to be fair, one or two of the OfCom people I've
talked to do take the engineering side seriously, and have been a bit
embarassed by the difficulty. Even they can't find some data. It seems not
to be fully tabulated in one place.

All seems 'need to know' and divided into parts on that basis so far as I
could tell. Mind you, I've had that from some at the BBC at times, as well.
:-)


So maybe they (or Java Jive) can help you do the integrations. No idea
how 'quick' that would be, though.

I'm flattered Jim!

I was just passing the buck for working out all the summations. :-)

An added complication, of course, is that the permitted antenna envelope
isn't actually the broadcast pattern. It just sets the max ERP *allowed* in
each direction. But ignoring that, you could just use the nominal ERP are
sum around the circle of values, weighted by the gains given. So the kind
of tedious sum computers are good at - provided you can get decent raw data
in a useable format for input. Which is the rub, here, I fear...

I never got a really satisfactory reason for why OfCom provided detailed
sheets for radio TXs, but not for digital TV. So although we have nominal
ERPs, frequencies, etc, I don't know of any available definative data that
includes details of the antenna patterns, etc.

Hence I have my doubts how anyone would easily find out a realistic value
for the total power use of the DTTV TX chain. OfCom don't seem to provide
'output' data from which it could be computed. And I suspect the companies
don't/won't tell others their electric bills!

Slainte,

Jim


Most main station antennas are 16 lambda, so you know the gain. Take off
a bit for feeder loss, combiner loss etc. For example, CP analogue has
an ERP of 1,000 kW and a box power of 80 kW, giving a gain of 12.5.

Relays usually have 4 or 8 lambda antennas, though some of the higher
power ones have 16 lambda cardioids.

Phil

In article , phil
wrote:

Most main station antennas are 16 lambda, so you know the gain.

Let me clarify. Do you mean a vertical array that extends for 16
wavelengths? Are all the elements in the array driven in phase with the
same amplitude? [1] How many elements along the "16 lambda"? Is the array
always symmetric in the horizontal plane, so give exactly the same ERP in
all horizontal directions?

Take off
a bit for feeder loss, combiner loss etc. For example, CP analogue has
an ERP of 1,000 kW and a box power of 80 kW, giving a gain of 12.5.

That's useful for two reasons. One is that you've just told us the "box
power" value of 80kW. If that is the power entering via the 'mains power
socket' then we don't actually need any of the details of the antenna to
answer Bill's basic question! :-)

Where is the value sourced from, and is there a list for all the TXs? Maybe
you can even quickly answer Bill's question for him. :-)

Slainte,

Jim

[1] One reason I'm asking is the cardioids you mentioned, so how much
do the vertical patterns vary from one TX to another?

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
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Audio Misc http://www.audiomisc.co.uk/index.html

In message , MarkU
writes
Rick wrote:
"J G Miller" wrote in message
...
On Wednesday, March 14th, 2012, at 18:32:41h +0000, Bob
pondered:

There's a Freeview re-tune for Mendip on 28th March.
I thought the DSO was done and dusted for Mendip?

You may have thought that, but it was not the case.

This is either the second or third retune for Mendip since
analog
switch off.


Please see


http://www.digitaluk.co.UK/propertym...ng_out_work/te
chnical_information/Long_Montain_Retune3

for Digital UK's explanation of why (and yes the URL is
correct for
Mendip even
though it says Long Mountain).


There was a previous retune on January 11th, 2011.

http://www.ukfree.TV/fullstory.php?storyid=1107051751

Today I had a message displayed on a bedroom TV (connected to a
Grundig USB Freeview receiver tuned to Mendip) informing me
that if I
was minus stations to do a full rescan, I checked and
everything
seemed to be OK so didn't bother, I thought that the rescan for
Mendip wouldn't be required until the 28th of this month

The same thing happened to me last night. You're right, it's not
until the 28th. I wonder how many boxes/sets have been re-tuned
needlessly as a result of this.

Mark


This is strange.

From Mendip I'm getting a message about the 28th, and have been all
week.

How can there be two different notifications from the same transmitter?
--
Ian

On 16/03/2012 17:07, Jim Lesurf wrote:
In , phil
wrote:

Most main station antennas are 16 lambda, so you know the gain.

Let me clarify. Do you mean a vertical array that extends for 16
wavelengths? Are all the elements in the array driven in phase with the
same amplitude? [1] How many elements along the "16 lambda"? Is the array
always symmetric in the horizontal plane, so give exactly the same ERP in
all horizontal directions?


Most main stations are omni-directional and the beam tilt is usually the
same in all directions. The elements are in a vertical array. To
reduce the ripple close in to the mast, phase and amplitude is varied
slightly.

Take off
a bit for feeder loss, combiner loss etc. For example, CP analogue has
an ERP of 1,000 kW and a box power of 80 kW, giving a gain of 12.5.

That's useful for two reasons. One is that you've just told us the "box
power" value of 80kW. If that is the power entering via the 'mains power
socket' then we don't actually need any of the details of the antenna to
answer Bill's basic question! :-)


The box power is the rf output power - I've no idea of their efficiency.

Where is the value sourced from, and is there a list for all the TXs? Maybe
you can even quickly answer Bill's question for him. :-)

Slainte,

Jim

[1] One reason I'm asking is the cardioids you mentioned, so how much
do the vertical patterns vary from one TX to another?


Vertical patterns for main stations vary very little from each other,
though beam tilt varies from site to site. Relays have a wide variety
of horizontal and vertical radiation patterns, especially the low power
ones.

Phil

In article , phil
wrote:
On 16/03/2012 17:07, Jim Lesurf wrote:
In , phil
wrote:

Most main station antennas are 16 lambda, so you know the gain.

Let me clarify. Do you mean a vertical array that extends for 16
wavelengths? Are all the elements in the array driven in phase with
the same amplitude? [1] How many elements along the "16 lambda"? Is
the array always symmetric in the horizontal plane, so give exactly
the same ERP in all horizontal directions?


Most main stations are omni-directional and the beam tilt is usually the
same in all directions. The elements are in a vertical array. To
reduce the ripple close in to the mast, phase and amplitude is varied
slightly.

You'd still need to know how many elements in the array to assess the max
gain value from the antenna array details. If the array is 'sparse' then
knowing its aperture is 16 wavelengths isn't sufficient. Although this is
irrelevant in this case, now, since you went on to tell us the actual power
and gain. :-)

[snip]

Vertical patterns for main stations vary very little from each other,
though beam tilt varies from site to site. Relays have a wide variety
of horizontal and vertical radiation patterns, especially the low power
ones.

So we'd need to have some kind of stats on the details to estimate how much
they contribute to the mains power draw compared to the main TXs.

I'm sure it is possible to estimate these things. But it isn't clear to me
how reliable any 'answer' we'd get for Bill on a 'quick' basis, lacking
many of the details. Maybe an order of magnitude would do. He hasn't said
so far as I know.

I'm responding to this because I am curious about the details, and the way
many of them don't seem to be easily available from sources like OfCom or
broadcasters. But I have no idea how anyone would get a 'quick' answer that
was meaningful without rather more info.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Jim Lesurf wrote:

I'm sure it is possible to estimate these things. But it isn't clear to me
how reliable any 'answer' we'd get for Bill on a 'quick' basis, lacking
many of the details. Maybe an order of magnitude would do.
Well that would be better than nothing. That was what I would expect
from the sparse information available.

Bill

In article , Bill Wright
wrote:
Jim Lesurf wrote:

I'm sure it is possible to estimate these things. But it isn't clear
to me how reliable any 'answer' we'd get for Bill on a 'quick' basis,
lacking many of the details. Maybe an order of magnitude would do.
Well that would be better than nothing. That was what I would expect
from the sparse information available.

In that case, what value do *you* get by making a 'quick' estimate for
yourself by a process like just summing the main ERPs and dividing by a
guesstimate factor? You are the person asking for the result and would
be deciding if a figure is "good enough" for your purposes. As it
stands we've don't seem to have someone else who has good data. And
if they do, and give a value, you'd still have to decide if their
approach was "good enough" for you.

In practice, if you had done this already you might already have
saved some days waiting for someone else to do it for you! And by
presenting your own estimate and workings you could at least give others
a chance to comment and suggest improvements, then make up your own mind.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

"Jim Lesurf" wrote in message
...
In article , Bill Wright
wrote:
Jim Lesurf wrote:

I'm sure it is possible to estimate these things. But it
isn't clear
to me how reliable any 'answer' we'd get for Bill on a
'quick' basis,
lacking many of the details. Maybe an order of magnitude
would do.
Well that would be better than nothing. That was what I would
expect
from the sparse information available.

In that case, what value do *you* get by making a 'quick'
estimate for
yourself by a process like just summing the main ERPs and
dividing by a
guesstimate factor? You are the person asking for the result
and would
be deciding if a figure is "good enough" for your purposes. As
it
stands we've don't seem to have someone else who has good data.
And
if they do, and give a value, you'd still have to decide if
their
approach was "good enough" for you.

In practice, if you had done this already you might already
have
saved some days waiting for someone else to do it for you! And
by
presenting your own estimate and workings you could at least
give others
a chance to comment and suggest improvements, then make up your
own mind.

Slainte,

Jim

--



May be a FoA request to Arqiva?


--
Woody

harrogate three at ntlworld dot com

On 18/03/2012 09:52, Jim Lesurf wrote:
In , Bill Wright
wrote:
Jim Lesurf wrote:

I'm sure it is possible to estimate these things. But it isn't clear
to me how reliable any 'answer' we'd get for Bill on a 'quick' basis,
lacking many of the details. Maybe an order of magnitude would do.
Well that would be better than nothing. That was what I would expect
from the sparse information available.

In that case, what value do *you* get by making a 'quick' estimate for
yourself by a process like just summing the main ERPs and dividing by a
guesstimate factor? You are the person asking for the result and would
be deciding if a figure is "good enough" for your purposes. As it
stands we've don't seem to have someone else who has good data. And
if they do, and give a value, you'd still have to decide if their
approach was "good enough" for you.

In practice, if you had done this already you might already have
saved some days waiting for someone else to do it for you! And by
presenting your own estimate and workings you could at least give others
a chance to comment and suggest improvements, then make up your own mind.

Slainte,

Jim


A rough estimate for the nearly defunct analogue is total ERP of 64MW,
which gives a box output power of around 5.5MW. Post DSO, total ERP is
around 18MW and box output of 1.6MW. I've no idea of the efficiencies
of modern UHF drives, so it's up to someone else to do some more guessing.

Phil