Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss
Freesat bit error rates
215 views
Skip to first unread message
Clive Page
Jun 8, 2015, 2:16:01 PM6/8/15
to
We have a small dish to get Freesat which feeds into our Panasonic TV
which is Freesat enabled. The TV can provide three indications of the
signal: strength, quality, and bit-error rate. Recently I had to move
the dish (to avoid a neighbour's tree which was starting to get in the
way) and so after re-aligning it had reason to check signal strength and
data quality of various channels.
All the local channels (BBC, ITV, etc) seem to have strength 10/10,
quality 10/10, and a bit-error rate of zero. But some of the more
exotic ones such as Bloomberg, CNN, and RT, while the strength is still
10/10 seem to show a lower quality, only 6 or 7/10, and sometimes show a
non-zero bit-error rate. All these channels seem to come from the same
satellite, Astra 28.2E, so I wondered why some appear to have a higher
quality than others. Is it something odd about my receiving set up, or
do some companies pay for a higher radiated power or bandwidth than others?
--
Clive Page
which is Freesat enabled. The TV can provide three indications of the
signal: strength, quality, and bit-error rate. Recently I had to move
the dish (to avoid a neighbour's tree which was starting to get in the
way) and so after re-aligning it had reason to check signal strength and
data quality of various channels.
All the local channels (BBC, ITV, etc) seem to have strength 10/10,
quality 10/10, and a bit-error rate of zero. But some of the more
exotic ones such as Bloomberg, CNN, and RT, while the strength is still
10/10 seem to show a lower quality, only 6 or 7/10, and sometimes show a
non-zero bit-error rate. All these channels seem to come from the same
satellite, Astra 28.2E, so I wondered why some appear to have a higher
quality than others. Is it something odd about my receiving set up, or
do some companies pay for a higher radiated power or bandwidth than others?
--
Clive Page
Andy Burns
Jun 8, 2015, 2:33:15 PM6/8/15
to
Clive Page wrote:
> All the local channels (BBC, ITV, etc) seem to have strength 10/10,
> quality 10/10, and a bit-error rate of zero. But some of the more
> exotic ones such as Bloomberg, CNN, and RT, while the strength is still
> 10/10 seem to show a lower quality, only 6 or 7/10, and sometimes show a
> non-zero bit-error rate. All these channels seem to come from the same
> satellite, Astra 28.2E,
One orbital position, but multiple satellites (two at 28.2E and one at
> All the local channels (BBC, ITV, etc) seem to have strength 10/10,
> quality 10/10, and a bit-error rate of zero. But some of the more
> exotic ones such as Bloomberg, CNN, and RT, while the strength is still
> 10/10 seem to show a lower quality, only 6 or 7/10, and sometimes show a
> non-zero bit-error rate. All these channels seem to come from the same
> satellite, Astra 28.2E,
28.5E) do you will tend to be closer aimed on some than others, you
might also not have quite the correct skew.
Bill Wright
Jun 8, 2015, 4:03:35 PM6/8/15
to
possible to favour one or another slightly by dish alignment. The field
strength at any given location on the ground also varies from sat to sat
and mux to mux. If you looked on a spectrum analyser you'd see that the
muxes as received vary by quite a few dB. This is a bally nuisance on
large distribution systems.
LNBs vary in their noise performance across the band. The noise will
usually give quite a humpy line across the analyser screen.
Bill
Andy Wade
Jun 8, 2015, 6:19:25 PM6/8/15
to
On 08/06/2015 21:03, Bill Wright wrote:
>
> LNBs vary in their noise performance across the band. The noise will
> usually give quite a humpy line across the analyser screen.
True, but most of the humpiness will be down to LNB gain and mismatch
>
> LNBs vary in their noise performance across the band. The noise will
> usually give quite a humpy line across the analyser screen.
loss variation with frequency, rather than variation in the front-end
noise figure. Since the gain is so high (50+ dB for a typical LNB) only
the front-end parameter variations - noise figure, dish gain &
equivalent noise temp, etc. - will have any significant effect on the BER.
Interference from other satellites in adjacent orbital slots and
terrestrial microwave links can also affect the received signal quality.
--
Andy
Brian-Gaff
Jun 9, 2015, 4:12:27 AM6/9/15
to
I also remember reading that the polarisation of signals can be upset by
weather differently at quite close frequencies. Its amazing it all works as
well as it does when you think about all the things that can vary in the
system.
Brian
--
From the Sofa of Brian Gaff Reply address is active
"Andy Wade" <spamb...@maxwell.myzen.co.uk> wrote in message
news:ctminb...@mid.individual.net...
weather differently at quite close frequencies. Its amazing it all works as
well as it does when you think about all the things that can vary in the
system.
Brian
--
From the Sofa of Brian Gaff Reply address is active
"Andy Wade" <spamb...@maxwell.myzen.co.uk> wrote in message
news:ctminb...@mid.individual.net...
R. Mark Clayton
Jun 11, 2015, 4:03:52 PM6/11/15
to
Added to which is the stuff at your end - size of dish, clarity of view (e.g. trees), S/N ratio of your LNB, length of cable run and sensitivity of your receiver...
Woody
Jun 17, 2015, 11:14:47 AM6/17/15
to
"Clive Page" <use...@page2.eu> wrote in message
news:ctm4ev...@mid.individual.net...
> We have a small dish to get Freesat which feeds into our Panasonic
> TV which is Freesat enabled. The TV can provide three indications
> of the signal: strength, quality, and bit-error rate. Recently I
> had to move the dish (to avoid a neighbour's tree which was starting
> to get in the way) and so after re-aligning it had reason to check
> signal strength and data quality of various channels.
This may sound daft but how do you know the tree is getting in the
> TV which is Freesat enabled. The TV can provide three indications
> of the signal: strength, quality, and bit-error rate. Recently I
> had to move the dish (to avoid a neighbour's tree which was starting
> to get in the way) and so after re-aligning it had reason to check
> signal strength and data quality of various channels.
way?
If the dish is vertical the signal line is 25deg above that which will
clear the top of most trees at surprisingly close range.
--
Woody
harrogate3 at ntlworld dot com
0 new messages