VHF DTT (TNT)

Bill Wright wrote:
"hwh" wrote in message
...
Channel E.4 won't be the problem, E.27 and E.30 will be. From December 11,
E. 30 will be used by a 60 kW DTT transmitter (using the Horizontal aerial
at 360 meters)

Those of us to the north-west of Belmont might as well forgett DTT until
2011 then.

I don't think that a 60 kW digital TX will cause more interference than
a 1000 kW analog one. And some time next year there will be four smaller
transmitters (5-20 kW) to replace the big (for DTT that is) one. Digital
allocations are smaller than analog ones, Channel E.30 will then only be
covering part of the South of the Netherlands with transmitters placed
close to major population centers.

gr, hwh

"hwh" wrote in message
...
Bill Wright wrote:
"hwh" wrote in message
...
Channel E.4 won't be the problem, E.27 and E.30 will be. From December
11, E. 30 will be used by a 60 kW DTT transmitter (using the Horizontal
aerial at 360 meters)

Those of us to the north-west of Belmont might as well forgett DTT until
2011 then.

I don't think that a 60 kW digital TX will cause more interference than a
1000 kW analog one. And some time next year there will be four smaller
transmitters (5-20 kW) to replace the big (for DTT that is) one. Digital
allocations are smaller than analog ones, Channel E.30 will then only be
covering part of the South of the Netherlands with transmitters placed
close to major population centers.

gr, hwh

Yes, I was just thinking that channel 30 is the BBC mux from Belmont which
is only 5kW, and Belmont analogue is regularly wiped out her by Dutch stuff.

Bill

wrote:
I think the UK should start HD DTT transmisions on VHF. Just about all
countries still use VHF Band III though Band I they are shutting down
now which is a shame for any TV DX'ers which pick up these
transmissions during the sporadic E season each year from May -
September

Band III for TV has a lot going for it, you can have far fewer lower
powered relays which have a much better coverage than UHF obviously


If by "band three" you mean VHF, even upper VHF, there is
the impulse noise problem. This is a killer at low VHF.
At high VHF, which is indeed used in the USA, it works,
but still impulse noise is a problem. You in Europe use a
modulation system that is MUCH more bothered by impulse
noise than is the US one, so you will be VERY unpleasantly
surprised at the necessary powers for it to be reliable.
It will work, just don't expect a power advantage over
UHF anywhere near what you probably do.

Doug McDonald

Gegroet,



Doug McDonald schreef:
It will work, just don't expect a power advantage over
UHF anywhere near what you probably do.

So what value do you then expect the power advantage to be?



Doug McDonald
Cheerio! Kr. Bonne.

Doug McDonald wrote:
It will work, just don't expect a power advantage over
UHF anywhere near what you probably do.

How much difference in power would you expect to need, between say 200
MHz and 600 MHz? For analog TV it is quite normal to have a Band III
transmitter to operate at 10% of the power of a UHF one on the same
tower and reaching the same area.

gr, hwh

hwh wrote:
Doug McDonald wrote:
It will work, just don't expect a power advantage over
UHF anywhere near what you probably do.

How much difference in power would you expect to need, between say 200
MHz and 600 MHz?


The relationship is 10 log (f2^2 / f1^2), or 20 log (f2 / f1):

20 log (600/200) = 9.54 dB


For analog TV it is quite normal to have a Band III
transmitter to operate at 10% of the power of a UHF one on the same
tower and reaching the same area.


Yes, 10^(9.54/10) = 9.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Find the cheapest Freeview & DAB prices:
http://www.digitalradiotech.co.uk/fr..._receivers.php
http://www.digitalradiotech.co.uk/dab/dab_radios.php

hwh wrote:
Doug McDonald wrote:
It will work, just don't expect a power advantage over
UHF anywhere near what you probably do.

How much difference in power would you expect to need, between say 200
MHz and 600 MHz? For analog TV it is quite normal to have a Band III
transmitter to operate at 10% of the power of a UHF one on the same
tower and reaching the same area.

gr, hwh

My point exactly

hwh wrote:
(snip)
I wonder what plans the international community has for band I. In
Europe it seems there aren't that many.

gr, hwh

I posted this last year and suddenly this and other postings reappear
from fe1.news.blueyonder.co.uk?

gr, hwh

[snip]
move to make way for FM band expansion.

What's not generally known is that 105 to 108 was used for the mobile
transmit part of what was the old VHF mid band with the base transmit
being around 139 "ish" odd. Not a very clever bit of planning, but at
that time?..


Slight error there Tone - and it is well known.

When the decision was made to put fuel and power together in the late
70's, they went to 107/138 with (ISTR) 30.5MHz Tx/Rx spacing (base Tx
high.) Then they were later pushed into trunking and went 138/148 with
(again ISTR) 9.5MHz spacing (base Tx now low.)

I suspect what you are really thinking of is the old Police 'P' band
which had base Tx on 100-104MHz with mobiles transmitting around
80-84MHz with uneven Tx/Rx spacing so that more than one channel could
be on talkthrough (a.k.a. repeat) on a given site without causing mutual
interference.

The Police were shoved out into 143/152 or 147/154 (both base Tx high)
under WARC in 1974 - which coincided with the county boundary changes.
The fuel and power industry moved later in the 70's and freed the whole
band.


--
Woody

harrogate three at ntlworld dot com