Channels 61 & 62 clearance plan

On 02/08/2012 14:00, I wrote:

http://www.maxwell.myzen.co.uk/uk.te...uly_Final1.pdf
or http://short.zen.co.uk/?id=12a4

Now taken down; use the link posted by Deri James.

--
Andy

On 03/08/2012 10:13, Jim Lesurf wrote:
In article , Andy Wade
wrote:

All (or almost all?) the band-edge channels have their transmissions
offset inwards, i.e. pretty-well all ch 21 muxes are on 21+

I assume you meant 61 and 61+ above...

No, 21(+) as written, referring to the lower band-edge.

This is nothing to do with receiver immunity, it's about the
broadcasters meeting a tight spec on out-of-band spurious emissions.
[...]

Would I be right to suspect that there *won't* be a mailshot of all
households in the effected areas telling where they can get such filters at
zero cost? :-)

I don't think that level of detail is decided yet.

Not knowing any better I'd guess that we could expect more than about 5-10
mV (75 Ohms) from the TV antenna to cause many problems. Does that sound
to be in the right ballpark? If not, what sort of value is typical for
domestic boxes, etc?

For a DTT box alone, quite a bit higher than that - I'd suggest around
-15 dBm (~95 dBuV) as a guideline. Of course as soon as you add preamps
and distribution systems etc., ahead of the tuner that figure could get
a lot lower, and...

Presumably, the decision to use 60-61 in the way was taken by men in suits
who just want maximum profit for the companies, etc... There seems little
sign of any engineers being involved above the level of being told to
impliment the changes.

.... therein lies the problem. It's engineering-driven, but seems to be
very much pushed by the mobile radio people who are predicting
phenomenal growth in mobile data take-up in the next decade, and want
every hertz of spectrum they can grab. IMHO Ofcom seems to have lost
some of the thoroughness of the former MPT/RA regime and (as I see it)
they failed to consider all aspects of the potential interference
problems - distribution systems being overlooked initially.

Another question is why was it decided that LTE would have its
base-transmit band below mobile-transmit, while all previous systems do
it the other way round?

--
Andy

On 03/08/2012 10:38, Ian Jackson wrote:

A filter will pass Ch60 unhindered, but reject 61 and above, will
probably be the size of a small car (and twice as expensive).

Whereas one with 3 or 4 dB insertion loss in ch 60 and 30 dB or more
rejection over 791 to 862 MHz will fit in the palm of your hand and can
be made for a couple of hundred quid - maybe much less.

--
Andy

Andy Wade wrote:

Would I be right to suspect that there *won't* be a mailshot of all
households in the effected areas telling where they can get such
filters at
zero cost? :-)

I don't think that level of detail is decided yet.
Of course it is. Everything has been planned out. Naive to think otherwise.

Bill

In message , Andy Wade
writes
On 03/08/2012 10:38, Ian Jackson wrote:

A filter will pass Ch60 unhindered, but reject 61 and above, will
probably be the size of a small car (and twice as expensive).

Whereas one with 3 or 4 dB insertion loss in ch 60 and 30 dB or more
rejection over 791 to 862 MHz will fit in the palm of your hand and can
be made for a couple of hundred quid - maybe much less.

But what do you get for a fiver? That's what they're going to have to
cost if they're going to distribute like confetti among those affected
by interference.
--
Ian

In article , Andy Wade
wrote:
On 03/08/2012 10:13, Jim Lesurf wrote:
In article , Andy Wade
wrote:

All (or almost all?) the band-edge channels have their transmissions
offset inwards, i.e. pretty-well all ch 21 muxes are on 21+

I assume you meant 61 and 61+ above...

No, 21(+) as written, referring to the lower band-edge.

Ok.

This is nothing to do with receiver immunity, it's about the
broadcasters meeting a tight spec on out-of-band spurious emissions.
[...]

Would I be right to suspect that there *won't* be a mailshot of all
households in the effected areas telling where they can get such
filters at zero cost? :-)

I don't think that level of detail is decided yet.

Which makes me feel the answer will turn out to be that people *won't* be
told.


Not knowing any better I'd guess that we could expect more than about
5-10 mV (75 Ohms) from the TV antenna to cause many problems. Does
that sound to be in the right ballpark? If not, what sort of value is
typical for domestic boxes, etc?

For a DTT box alone, quite a bit higher than that - I'd suggest around
-15 dBm (~95 dBuV) as a guideline.

About 56 mV? I'm quite surprised it is that high. However I guess I'm
judging this by Band 2 FM tuner standards, not DVB-T.


Presumably, the decision to use 60-61 in the way was taken by men in
suits who just want maximum profit for the companies, etc... There
seems little sign of any engineers being involved above the level of
being told to impliment the changes.

... therein lies the problem. It's engineering-driven, but seems to be
very much pushed by the mobile radio people who are predicting
phenomenal growth in mobile data take-up in the next decade, and want
every hertz of spectrum they can grab. IMHO Ofcom seems to have lost
some of the thoroughness of the former MPT/RA regime and (as I see it)
they failed to consider all aspects of the potential interference
problems - distribution systems being overlooked initially.

My recollection from knowing and working with some RA people before the RA
was 'absorbed' is that the bulk of the engineering expertise was discarded
in the process.

Witness other questionable developements like 'white space' and 'home
networks over mains'.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
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On 04/08/2012 10:10, Jim Lesurf wrote:

About 56 mV? I'm quite surprised it is that high. However I guess I'm
judging this by Band 2 FM tuner standards, not DVB-T.

OK, maybe that was a bit optimistic. The best receivers should cope at
that level[1,2], provided the DTT signal is strong enough (so that C/I
30 dB). If you want a more conservative figure drop it by 10 dB to -25
dBm. Many of the protection ratio tests in the D-book are based on
interferer levels of -25 (these are mandatory to get pink tick status).

[1] i.e. -15 dBm
[2] Have a look at Mark Waddell's paper, which you can get from he
http://www.cai.org.uk/information/do...wnload&cid=207

My recollection from knowing and working with some RA people before the RA
was 'absorbed' is that the bulk of the engineering expertise was discarded
in the process.

Hence more reliance on consultants - some of them are very good.

Witness other questionable developements like 'white space' and 'home
networks over mains'.

White space should be OK, provided they get the geolocation to work
properly. 'Spose it could be problem if there's a massive 'opening' though.

PLT's a EMC disaster and they should have acted.

--
Andy

On 03/08/2012 22:54, Andy Wade wrote:
On 02/08/2012 14:00, I wrote:

http://www.maxwell.myzen.co.uk/uk.te...uly_Final1.pdf

or http://short.zen.co.uk/?id=12a4

Now taken down; use the link posted by Deri James.

Now gone as well, though still in Google cache.

On 06/08/2012 20:38, Jim wrote:
On 03/08/2012 22:54, Andy Wade wrote:
On 02/08/2012 14:00, I wrote:

http://www.maxwell.myzen.co.uk/uk.te...uly_Final1.pdf

or http://short.zen.co.uk/?id=12a4

Now taken down; use the link posted by Deri James.

Now gone as well, though still in Google cache.

Try this for Version 2 - http://short.zen.co.uk/?id=12a8

--
Andy

Andy Wade wrote:

Try this for Version 2 - http://short.zen.co.uk/?id=12a8

~13months to retune ~350 MUXes, can't they afford to allocate more than
one man, one dog and one van?