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Predicting com7/8 SFN reception deterioration due to CCI



 
 
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  #41  
Old August 13th 19, 06:08 PM posted to uk.tech.digital-tv
Robin[_10_]
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Posts: 114
Default Predicting com7/8 SFN reception deterioration due to CCI

On 13/08/2019 15:45, Jim Lesurf wrote:
In article , Bob Latham
wrote:

I think T2 was around in 2010 -ish. So next year if you have kit which
cannot receive T2 then it is either more than 10 years old or you
purchased something that had a short life expectancy and would probably
have been as cheap as chips. Swap the lot to T2 ASAP.


FWIW I agree. The reality is that this is another example of the OGP (Old
Grannie Problem) Duplication on -T and -T2 is wasteful. So my vote would be
for shifiting everything to T2 before the muxes get weeded.


I'd like to know first how many old grannies - and others, such as poor
families, some with more than one TV to keep the kids happy - would have
to spend how much on new hardware and on help to set it up. But then
I'm old fashioned and still hanker after evidence-based policy making.


--
Robin
reply-to address is (intended to be) valid
  #42  
Old August 13th 19, 06:19 PM posted to uk.tech.digital-tv
Ulrich Onken[_3_]
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Posts: 45
Default Predicting com7/8 SFN reception deterioration due to CCI

On 12.08.2019 16:33, Bob Latham wrote:
In article ,
Bill Wright wrote:


Some of these txs will be well over the horizon so you will receive
zero signal under normal conditions.


Bill


So obvious when you think about it but it honestly never crossed my
mind.


Thanks Bill.


The prediction tool at https://fmscan.org/main.php takes into account
the attenuating effect by the radio horizon to some extent. When
selecting "TV" and "frequency list" for Stourbridge and extending the
radius to 150 km in the filter options, the following relative field
strengths are predicted for COM7/8 at your location:

Ch location dist. azim pwr dB

E55 Sutton Coldfield 16mi 54 89 72dB
E55 Hereford/Ridge Hill 37mi 208 10 43dB
E55 Moel-y-Parc 71mi 317 16 30dB
E56 Sutton Coldfield 16mi 54 86 71dB
E56 Hereford/Ridge Hill 37mi 208 9.8 43dB
E56 Waltham 60mi 67 13 35dB
E56 Fenton 37mi 359 0.28 25dB

The strongest signals should clearly come from Sutton Coldfield, Waltham
from a similar direction is approximately 30 dB weaker. COM7 at Waltham
is shown still on channel 31.

You can also switch to a map, with the transmitter locations indicated.

Regards,
Uli
  #43  
Old August 13th 19, 08:17 PM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Posts: 2,527
Default Predicting com7/8 SFN reception deterioration due to CCI

On Tue, 13 Aug 2019 15:41:47 +0100, Jim Lesurf
wrote:

But BBC FOUR transmits a number of items like Prom concerts. It would be
nice to think these might get shifted to BBC 2 if FOUR is axed, but I have
my doubts that'll happen. So the fallback *might* be that BBC FOUR HD
continues via the internet. The snag *there* being a lower level of
detail/quality for both picture and sound. Which doesn't matter much for
news, but matters a lot for something like a Prom!


If only they'd let Amazon or Netflix handle it, rather than putting it
on their own iPlayer app, the quality should be OK.

Rod.
  #44  
Old August 13th 19, 08:30 PM posted to uk.tech.digital-tv
Andy Burns[_12_]
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Default Predicting com7/8 SFN reception deterioration due to CCI

Ulrich Onken wrote:

COM7 at Waltham is shown still on channel 31.


That's correct for now, COM8 has moved to 56, but COM7 hasn't (yet)
moved to 55
  #45  
Old August 13th 19, 09:23 PM posted to uk.tech.digital-tv
Indy Jess John
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Posts: 1,616
Default Predicting com7/8 SFN reception deterioration due to CCI

On 13/08/2019 18:08, Robin wrote:
On 13/08/2019 15:45, Jim Lesurf wrote:
In , Bob Latham
wrote:

I think T2 was around in 2010 -ish. So next year if you have kit which
cannot receive T2 then it is either more than 10 years old or you
purchased something that had a short life expectancy and would probably
have been as cheap as chips. Swap the lot to T2 ASAP.


FWIW I agree. The reality is that this is another example of the OGP (Old
Grannie Problem) Duplication on -T and -T2 is wasteful. So my vote would be
for shifiting everything to T2 before the muxes get weeded.


I'd like to know first how many old grannies - and others, such as poor
families, some with more than one TV to keep the kids happy - would have
to spend how much on new hardware and on help to set it up. But then
I'm old fashioned and still hanker after evidence-based policy making.


I also dislike the idea of throwing away perfectly serviceable equipment
just so that somebody can have the screen resolution to count the number
of twigs on a tree in winter.

In the analogue days, you tuned things in when they were bought and
didn't need to touch them again until they stopped working because they
were broken. It is bad enough having to retune now and again because
somebody had the bright idea of shuffling channels around, and even that
can make an SD channel out of reach it it is moved from a T1 to a T2
mux, but to contribute to the waste of today's disposable society just
because the technology makes it possible is a policy designed to make
the poorest suffer the most.

I have a T2 TV so I can watch anything live, but my elderly but fully
serviceable PVR can't receive anything on a T2 mux. I don't mind
watching things in SD since my eyesight isn't wonderful, but I will be
really unhappy if I have to replace it just because duplicating a
channel on SD and HD looks wasteful. It is nowhere near as wasteful as
throwing serviceable physical equipment away!

Jim

  #46  
Old August 13th 19, 10:16 PM posted to uk.tech.digital-tv
NY[_2_]
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Posts: 74
Default Predicting com7/8 SFN reception deterioration due to CCI

Indy Jess John" wrote in message
...
I also dislike the idea of throwing away perfectly serviceable equipment
just so that somebody can have the screen resolution to count the number
of twigs on a tree in winter.

In the analogue days, you tuned things in when they were bought and didn't
need to touch them again until they stopped working because they were
broken. It is bad enough having to retune now and again because somebody
had the bright idea of shuffling channels around, and even that can make
an SD channel out of reach it it is moved from a T1 to a T2 mux, but to
contribute to the waste of today's disposable society just because the
technology makes it possible is a policy designed to make the poorest
suffer the most.

I have a T2 TV so I can watch anything live, but my elderly but fully
serviceable PVR can't receive anything on a T2 mux. I don't mind watching
things in SD since my eyesight isn't wonderful, but I will be really
unhappy if I have to replace it just because duplicating a channel on SD
and HD looks wasteful. It is nowhere near as wasteful as throwing
serviceable physical equipment away!


I fully agree. I have been through several set top boxes since digital has
been available:

- a TopUpTV box that became obsolete when some of the multiplexes changed
their guard interval or symbol rate or whatever

- a bog-standard T1 replacement

- a T2 replacement to receive HD and SD-over-T2 channels

My TV was probably one of the last to be made that didn't have built-in
digital decoder, though at least it had HDMI so I could feed it with an HD
signal from the last of the three boxes.

STBs are a pain in the proverbial when you want to record from two different
channels while you are out. It's a shame that there wasn't an
industry-standard control bus for making a VHS VCR tell an STB to change
from one channel to another.

All that is ancient history now. I still have the VHS recorder in case I
want to copy any old tapes to MPEG, but for a long time I've used a computer
and T1 or T1/T2 decoder to record everything, which has the advantage that I
can edit out commercials and continuity announcements. How did we ever
survive with linear recording to tape, with an absolute maximum recording
time of 15 hours per tape (5-hour tape on EP speed) which imposes a limit on
the length of unattended recordings.

Nowadays all I need is a Raspberry Pi, a satellite or terrestrial decoder,
and PVR software such as TVHeadend or NextPVR - and a nice big external HDD
to put it all on.

  #47  
Old August 14th 19, 12:28 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 3,564
Default Predicting com7/8 SFN reception deterioration due to CCI

On 12/08/2019 16:12, Bob Latham wrote:

I am using Sutton but I'm not sure it is clear line of site, it might
be, I don't know. It is 16 miles away.

Bob.

Can you see it?

Bill
  #48  
Old August 14th 19, 12:35 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 3,564
Default Predicting com7/8 SFN reception deterioration due to CCI

On 12/08/2019 16:25, Bob Latham wrote:

I suppose you've done it all and got a house full of tea shirts.


It's actually rather a shame that I don't find the theoretical side
interesting any more. Some people leave an occupation and keep the
interest. I haven't.

I like Yorkshire tea. I don't wear shirts.

Bill
  #49  
Old August 14th 19, 12:36 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 3,564
Default Predicting com7/8 SFN reception deterioration due to CCI

On 12/08/2019 17:05, Jim Lesurf wrote:

I expect the slope on each mux is an artefact of AGC or similar


Not necessarily.


They look credible for off-air signals plus cable peculiarities etc.

Bill
  #50  
Old August 14th 19, 09:27 AM posted to uk.tech.digital-tv
Mark Carver
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Posts: 6,528
Default Predicting com7/8 SFN reception deterioration due to CCI

On 13/08/2019 15:41, Jim Lesurf wrote:

But BBC FOUR transmits a number of items like Prom concerts. It would be
nice to think these might get shifted to BBC 2 if FOUR is axed, but I have
my doubts that'll happen. So the fallback *might* be that BBC FOUR HD
continues via the internet. The snag *there* being a lower level of
detail/quality for both picture and sound. Which doesn't matter much for
news, but matters a lot for something like a Prom!


What's wrong with D-Sat ?
 




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