Angus Transmitter
 

I have a USB digital tuner for my computer and get my signal from the Angus
transmitter. However the signal is not all that strong but I can live with
it short term as I only use it to watch something different from Sky. It is
only one mux that is dodgy.

Even the analogue channels are not all that great. I really need a new
aerial but when the Angus transmitter analogue is switched off I presume
that the digital signal strength will increase.

If so, I will just persevere with my present aerial. So will the signal
strength be increased?

Dave

Angus Transmitter
 

"Dave" wrote in message
. ..
I have a USB digital tuner for my computer and get my signal
from the Angus transmitter. However the signal is not all that
strong but I can live with it short term as I only use it to
watch something different from Sky. It is only one mux that is
dodgy.

Even the analogue channels are not all that great. I really
need a new aerial but when the Angus transmitter analogue is
switched off I presume that the digital signal strength will
increase.

If so, I will just persevere with my present aerial. So will
the signal strength be increased?

Dave





If you need a new aerial (why?) then get a new aerial. It matters
not whether the transmitter e.r.p. is increased post DSO, your
receiver will still work. If power was being reduced it would be
a different matter.


--
Woody

harrogate three at ntlworld dot com

Angus Transmitter
 

If you need a new aerial (why?) then get a new aerial.

Nobody *needs* to watch TV, clearly the O/P is willing to avoid the
expense of a new aerial and put up with current reception problems for
10 more months if reception will improve at DSO.

Clearly reception will improve, if only one mux is currently difficult
then at a rough guess the extra power post-DSO will be sufficient, even
though the muxes are now and will remain in-group for a C/D aerial they
will shuffle down from 56-68 to 53-61 which should help a little too.

Angus Transmitter
 

Not all poor reception is due to low signals, it could be cross modulation,
reflections or rain getting in the works or even physical damage to the
aerial, and no amount of extra signal will help those problems, and when the
switchover comes, you can bet your wotsit that.. A: all aerial riggers will
suddenly be very busy, and B: you will find it does not wrk as it is and the
prices will be higher.

Its Murphy's law, and for all those called Murphy, apologies.

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Dave" wrote in message
. ..
I have a USB digital tuner for my computer and get my signal from the Angus
transmitter. However the signal is not all that strong but I can live with
it short term as I only use it to watch something different from Sky. It is
only one mux that is dodgy.

Even the analogue channels are not all that great. I really need a new
aerial but when the Angus transmitter analogue is switched off I presume
that the digital signal strength will increase.

If so, I will just persevere with my present aerial. So will the signal
strength be increased?

Dave

Angus Transmitter
 

"Andy Burns" wrote in message
...

If you need a new aerial (why?) then get a new aerial.

Nobody *needs* to watch TV, clearly the O/P is willing to avoid the
expense of a new aerial and put up with current reception problems for 10
more months if reception will improve at DSO.

Clearly reception will improve, if only one mux is currently difficult
then at a rough guess the extra power post-DSO will be sufficient, even
though the muxes are now and will remain in-group for a C/D aerial they
will shuffle down from 56-68 to 53-61 which should help a little too.

I maybe only watch one or two programmes a week on CH 5 digital TV as the
Angus transmitter does not have CH 5 analogue.

It is just that the aerial was erected before I got a garage built on the
side of the house and it would need, so I have been told, scaffolding to put
a better aerial up there.

I cannot even get subsidised cavity wall insulation because of that unless I
pay for scaffolding.

That is the only use I make of the aerial as I have Sky+ and I watch it
when there is a clash between what my wife is watching and recording at the
same time.

I can live with it until analogue is switched off.

Dave

Angus Transmitter
 

On Wed, 04 Nov 2009 23:54:08 GMT, "Dave"
wrote:
snip
I have a USB digital tuner for my computer and get my signal from the Angus
transmitter. However the signal is not all that strong but I can live with
it short term as I only use it to watch something different from Sky. It is
only one mux that is dodgy.

snip

I regularly struggle with the Angus transmitter from which I am 16
miles behind some hills on a bearing of 62 deg. In theory Mux 1 should
always be strong enough but it only takes a wet, misty evening (not
uncommon in this part of the world!) for me to get the dreaded poor
signal message on BBC1/2. I then sometimes find a retune picks up
Durris satisfactorily. This 53 miles away on a bearing of 44 deg but
transmits at 5x the power of Angus. I have a fairly new decent quality
aerial of the right group properly aligned on Angus.

Why is it that DAB can amalgamate the output of several transmitters
and when listening to a digital radio channel you can be receiving
from more than one transmitter at a time but DTT signals all have to
use different frequencies from different transmitters? Would it be
possible technically for all transmitters in a given TV region to use
the same frequencies and the total signal accumulated in some way?

Angus Transmitter
 

On 07/11/09 13:50, ChrisW wrote:

Why is it that DAB can amalgamate the output of several transmitters
and when listening to a digital radio channel you can be receiving
from more than one transmitter at a time but DTT signals all have to
use different frequencies from different transmitters?

Because the BBC use an SFN for their national DAB mux, but SFNs are not
used for DVB-T in this country (apart from a few localised ones I gather).

Angus Transmitter
 

In article , ChrisW
wrote:
On Wed, 04 Nov 2009 23:54:08 GMT, "Dave" wrote:


I regularly struggle with the Angus transmitter from which I am 16 miles
behind some hills on a bearing of 62 deg. In theory Mux 1 should always
be strong enough but it only takes a wet, misty evening (not uncommon in
this part of the world!) for me to get the dreaded poor signal message
on BBC1/2. I then sometimes find a retune picks up Durris
satisfactorily. This 53 miles away on a bearing of 44 deg but transmits
at 5x the power of Angus. I have a fairly new decent quality aerial of
the right group properly aligned on Angus.

I also get a stronger and more reliable DTTV signal from Durris (78km away)
than from Angus (27km). This also despite it being at the HF end of the
band. Are the patterns of these TXs published now?

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

Angus Transmitter
 

Why is it that DAB can amalgamate the output of several transmitters
and when listening to a digital radio channel you can be receiving
from more than one transmitter at a time but DTT signals all have to
use different frequencies from different transmitters? Would it be
possible technically for all transmitters in a given TV region to use
the same frequencies and the total signal accumulated in some way?

There's a trade off between the amount of data that can be fitted in to a
given bandwidth and the maximum distance between transmitters before the
signals start to interfere with each other, rather than help each other. The
numbers are wrong for Single Frequency Networks to work in the pre-DSO
incarnation of DTT in the UK.

Bill

Angus Transmitter
 

On 7 Nov., 17:39, "Bill" wrote:
The numbers are wrong for Single Frequency Networks
to work in the pre-DSO incarnation of DTT in the UK.

Bill

The maximum distance between two DVB-T transmitters
is about 67 km before the signals start interfering
rather than just adding in a helpful way.
The 67 km comes from the product of the speed
of light 3E8 m/s and the 'Guard Interval'.
In the UK the GI is 28 usec = 8.4km (8k mode) while
in Germany it is 224 usec = 67.2km

With DVB-T such a '67 km' SFN will have a bitrate
of just 20 Mbps/mux and not the UK 24.13 Mbps/mux.
(17% loss of capacity).

If you draw a map of the larger TX mast/towers
in the UK - the distance between them is mostly
well above 67 km. And new masts are very big money.

In addition, if very many transmitters used the same
frequency in a very large SFN, the total signal from
all transmitters more than 67km apart would
increase the general background noise level
- called SFN self interference. This problem
is much worse with higher modulations e.g.
16/64-QAM than with the primitive low bitrate
4-QAM used by DAB (and DAB+)

Now enter DVB-T2 with its 16k and 32k modes, longer
Guard Intervals, rotated constellations and very much
better error correction codes. Now large SFN's is very
much more possible for a DTT network.

The guard interval can be more than two times larger,
but the capacity lost from SFN operation more like
just 5-8%.
With the GI in the range of 135-160 km it will
only be very distant transmitters that need
contribute to the self interference.

The UK do not have UHF channels allocated by
the ITU (GE06) for a nationwide SFN in the
UHF bands (470-790 MHz).
One may think that channel 36 could (almost) be used.
The channels 35 and 37 may also be able to cover
large parts of the UK.

It is not easy nor inexpensive to implement
such SFN's, but now it is for the first time
technically not impossible.

Lars :)

Angus Transmitter
 

The numbers are wrong for Single Frequency Networks
to work in the pre-DSO incarnation of DTT in the UK.

Bill

The maximum distance between two DVB-T transmitters
is about 67 km before the signals start interfering
rather than just adding in a helpful way.
The 67 km comes from the product of the speed
of light 3E8 m/s and the 'Guard Interval'.
In the UK the GI is 28 usec = 8.4km (8k mode) while
in Germany it is 224 usec = 67.2km

With DVB-T such a '67 km' SFN will have a bitrate
of just 20 Mbps/mux and not the UK 24.13 Mbps/mux.
(17% loss of capacity).

If you draw a map of the larger TX mast/towers
in the UK - the distance between them is mostly
well above 67 km. And new masts are very big money.

In addition, if very many transmitters used the same
frequency in a very large SFN, the total signal from
all transmitters more than 67km apart would
increase the general background noise level
- called SFN self interference. This problem
is much worse with higher modulations e.g.
16/64-QAM than with the primitive low bitrate
4-QAM used by DAB (and DAB+)

Now enter DVB-T2 with its 16k and 32k modes, longer
Guard Intervals, rotated constellations and very much
better error correction codes. Now large SFN's is very
much more possible for a DTT network.

The guard interval can be more than two times larger,
but the capacity lost from SFN operation more like
just 5-8%.
With the GI in the range of 135-160 km it will
only be very distant transmitters that need
contribute to the self interference.

The UK do not have UHF channels allocated by
the ITU (GE06) for a nationwide SFN in the
UHF bands (470-790 MHz).
One may think that channel 36 could (almost) be used.
The channels 35 and 37 may also be able to cover
large parts of the UK.

It is not easy nor inexpensive to implement
such SFN's, but now it is for the first time
technically not impossible.

Lars :)

Nice post. Thanks.


--
Graham.

%Profound_observation%

Angus Transmitter
 

such SFN's, but now it is for the first time
technically not impossible.

Lars :)

Nice post. Thanks.


Yes, agreed. I've filed it away so I hope it's right. . .

Bill