Signal strenght reading


Luca Bertagnolio <lucaberta@...>
 

Folks,

been reading the nice posting on the other list, and I'd like to add
my 2 europennies to the discussion.

With my extra-small dish setup (40cm in a plastic bucket, look for
luca-dish.jpg in http://groups.yahoo.com/group/SatSignal/files/ ) and
the USB version of the SkyStar2 adapter my signal strength is
anywhere from 8% (deep red) to 22-23% (barely yellow), and yet I can
receive 100% of the data, of course if the weather is nice.

So, maybe the signal level is not so important after all... maybe
it's very quick changes in the signal level due to local weather like
heavy rain or hail that create the issue, but definitely not a low
signal strenght.

Bye, Luca


David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

With my extra-small dish setup (40cm in a plastic bucket, look for
luca-dish.jpg in http://groups.yahoo.com/group/SatSignal/files/ )
and the USB version of the SkyStar2 adapter my signal strength is
anywhere from 8% (deep red) to 22-23% (barely yellow), and yet I can
receive 100% of the data, of course if the weather is nice.


Luca,

Do we know how the signal strength readings compare on the USB and
PCI versions? I know that when my PCI card indication drops below
50% (yellow, I thnk) the BER goes up quite noticeably and segment
drop-outs do occur.

I rather suspect these signal strength indicators are rather like S-
meters on amateur radio kit, mostly meaningless, perhaps
occasionally useful for comparitive measurements, but calibrated to
any absolute standard, definitely not!! Actually, it's worse than
that, because of the digital threshold/capture effect we are looking
at very small changes in signal strength between no signal and OK.
This implies, perhaps, a reading accuracy requirement of 1dB, surely
a much tighter specification than any consumer equipment is made to?

Comments welcomed!

Cheers,
David


Luca Bertagnolio <lucaberta@...>
 

--- In MSG-1@yahoogroups.com, "David Taylor" <david-taylor@b...>
wrote:
Do we know how the signal strength readings compare on the USB and
PCI versions? I know that when my PCI card indication drops below
50% (yellow, I thnk) the BER goes up quite noticeably and segment
drop-outs do occur.
very good point David. Next step is to plug in the SkyStar2 PCI card
I have to check if there is any major difference. I have both a 2.3
and a 2.6 version, so I can also see if there is any big difference
between the two (and I am sure there is, reading other people's
email).

I'll let you once I'll do these tests.

Bye, Luca


Luca Bertagnolio <lucaberta@...>
 

--- In MSG-1@yahoogroups.com, "Luca Bertagnolio" <lucaberta@y...>
wrote:
very good point David. Next step is to plug in the SkyStar2 PCI
card
I have to check if there is any major difference. I have both a
2.3
and a 2.6 version, so I can also see if there is any big difference
between the two (and I am sure there is, reading other people's
email).
wow! There are major differences, no doubt about that! The signal
meter on the SkyStar2 2.3 PCI card now ranges between 40 and 49%.

With the version 2.6 card, the signal level is between 18 and 25%.

It's official, the signal level meter on the SkyStar2 is broken!

Bye, Luca


Alan Sewards <alan.sewards@...>
 

Hi all,
I didn't see any reply to this posting, but does anyone know what the
Signal Quality indication is based on? Usually with digital satellite
channels, raw strength is shown as Signal Strength (presumably C/N), and
some factor based on error rates is used to show Signal Quality. Those of
you who have Sky systems can see these two indications, and it is
interesting to move the dish slightly and watch them. A tiny movement will
have no effect on signal strength but a pronounced one on Signal Quality.
For the TechniSat card, Signal Quality is obviously not the same as the BER,
as in my case the BER has always been zero, but the SQ hovers around 70%, so
exactly what is being measured here? In my early days as a satellite
communicator, we used to measure Eb/No as a sensitive measure of channel
quality, as well as C/No (more mundane). One could also look at the eye
diagram and draw analog conclusions from that.

BTW, the recent changes to MDM to mitigate the effects of late or
missing segments has had a dramatic effect on the Animations, which are now
almost perfect (at least they would be if there weren't any missing cycles).
Congratulations to David and his team of eagle-eyed observers, and many
thanks from one who has benefitted.

Best regards - Alan

----- Original Message -----
From: "Luca Bertagnolio" <lucaberta@yahoo.com>
To: <MSG-1@yahoogroups.com>
Sent: Tuesday, October 07, 2003 3:33 PM
Subject: [MSG-1] Re: Signal strenght reading


--- In MSG-1@yahoogroups.com, "David Taylor" <david-taylor@b...>
wrote:
Do we know how the signal strength readings compare on the USB and
PCI versions? I know that when my PCI card indication drops below
50% (yellow, I thnk) the BER goes up quite noticeably and segment
drop-outs do occur.
very good point David. Next step is to plug in the SkyStar2 PCI card
I have to check if there is any major difference. I have both a 2.3
and a 2.6 version, so I can also see if there is any big difference
between the two (and I am sure there is, reading other people's
email).

I'll let you once I'll do these tests.

Bye, Luca




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a_van_belle
 

Hello Alan,

The signal Quality reading is probably based on a calculated SNR
figure. It is linked to the SNR reading.

I did put in a line-amp to see what happend, the reading did not
change. At my recent peak solar outage it dropped from 71-79 % to 59
% while my satsignal meter reading increased !

The BER reading is set to zero by the software when it is very small.
Only at SQ 59% I noticed that it showed 5.46 E-7 for a couple of
seconds.
The SQ bar is green when above 40%, yellow from 30 to 40% and red
below 30 %.

Unfortunately the signal quality reading is not calibarted !
The new Skystar2 card (rev 2.6b) does readout about 12 % less
compared to rev2.3. Of course I swapped cables from my dual output
LNB and I even swapped the two cards.
When rev 2.3 reads 70-79% and SNR 11.6 dB, the rev2.6B does 62% and
SNR 9.9 dB.

By the way the new version does show a more stable SQ reading but
does not show the BER field anymore !
So if you would like to know what version PCI card you have, check
the Status screen, if BER is present you have rev 2.3.
On the other hand I did notice that the new version 2.6b does run
very cool compared to rev 2.3.

During extensive tests, running both systems simultatniously I never
saw any difference in segment loss, so there is no need to upgrade
your PCI card.

Greetings,
Arne van Belle