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Definitions and questions!

David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

Speaking from a position of ignorance, what is meant by "Signal
Quality" in the Transponder Status display? It seems to be rather
like the S-meter in amateur radio, an arbitrary indication of signal
strength as seen by the receiver (so in fact would be more
accurately called quantity than quality!). Am I correct? Is there
a standard?

Having asked that: why would adding a splitter increase the signal
quality? (OK, receiver overload would be less in a lower signal
level situation). But if the quality is actually measuring the
quantity, then it should indicate less!

Or is the kit simply so cheap that any absolute indications from it
should be ignored?

Cheers,
David

Peter Benney <tugboat@...>
 

Speaking from a position of ignorance, what is meant by "Signal
Quality" in the Transponder Status display? It seems to be rather
like the S-meter in amateur radio, an arbitrary indication of signal
strength as seen by the receiver (so in fact would be more
accurately called quantity than quality!). Am I correct? Is there
a standard?
David,

I think the major difference is that signal quality is assessed after demodulation and takes into account channel power, carrier/noise and bit error ratio.

I have now reverted to my original setup with the PCI card fed through the loopthrough of a digital satellite receiver. The receiver shows the 11096 tp Signal 88% and quality 100%.
Whether connected via the loopthrough or or directly from the LNB there is no change in the Setup4PC Quality, SNR or BER. I have a splitter somewhere and when I find it will feed the PCI card and STB from the same LNB and see if there is any change.

My lost segment problem is now a thing of the past although a few expletives were expressed at midday today !

Google searches have been interesting, "DVB signal assessment" turned up the a paper on the reproduction of the newts !

Cheers,

Peter

Alan Sewards <alan.sewards@...>
 

David,
Arne and I discussed this on MSG-1 group on 12 October. I'm am fairly
sure that Signal Quality is a measure of S/N, and probably improves if a
splitter is fitted because of reduction of overload or subtle changes in
receiver parameters with changes in signal level. Easiest way to check is to
exchange the splitter for an attenuator!

Best regards - Alan

----- Original Message -----
From: "David Taylor" <david-taylor@...>
To: <MSG-1@...>
Sent: Sunday, November 09, 2003 1:11 PM
Subject: [MSG-1] Definitions and questions!


Speaking from a position of ignorance, what is meant by "Signal
Quality" in the Transponder Status display? It seems to be rather
like the S-meter in amateur radio, an arbitrary indication of signal
strength as seen by the receiver (so in fact would be more
accurately called quantity than quality!). Am I correct? Is there
a standard?

Having asked that: why would adding a splitter increase the signal
quality? (OK, receiver overload would be less in a lower signal
level situation). But if the quality is actually measuring the
quantity, then it should indicate less!

Or is the kit simply so cheap that any absolute indications from it
should be ignored?

Cheers,
David



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David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

--- In MSG-1@..., "Alan Sewards" <alan.sewards@c...>
wrote:
David,
Arne and I discussed this on MSG-1 group on 12 October. I'm am
fairly sure that Signal Quality is a measure of S/N, and probably
improves if a splitter is fitted because of reduction of overload or
subtle changes in receiver parameters with changes in signal level.
Easiest way to check is to exchange the splitter for an attenuator!

Best regards - Alan
Yes, I found that after a little looking. I have tried to find the
specs of the B2C2 chip and other component of the SkyStar card, in
the hope of finding something more like an engineering manual that I
could understand! The B2C2 card is purely digitial, so that doesn't
help, I can't find the part number for the tuner, and the chip next
to it is hidden under a heatsink!

In any case, if all these cards need lower signal strength to
perform well, shouldn't AGC be doing something about that? Is "our"
transponder being hidden in a mush of intermodulation from the
others?

Cheers,
David

pa3aod <harms@...>
 

Hi David,

I found some info on the WEB about the B2C2 chip(and software), look
at the following web-pages www.bbti.us and www.b2c2.com.

Bert PA3AOD



--- In MSG-1@..., "David Taylor" <david-taylor@b...>
wrote:
--- In MSG-1@..., "Alan Sewards" <alan.sewards@c...>
wrote:
David,
Arne and I discussed this on MSG-1 group on 12 October. I'm
am
fairly sure that Signal Quality is a measure of S/N, and probably
improves if a splitter is fitted because of reduction of overload
or
subtle changes in receiver parameters with changes in signal level.
Easiest way to check is to exchange the splitter for an attenuator!

Best regards - Alan
Yes, I found that after a little looking. I have tried to find the
specs of the B2C2 chip and other component of the SkyStar card, in
the hope of finding something more like an engineering manual that
I
could understand! The B2C2 card is purely digitial, so that
doesn't
help, I can't find the part number for the tuner, and the chip next
to it is hidden under a heatsink!

In any case, if all these cards need lower signal strength to
perform well, shouldn't AGC be doing something about that?
Is "our"
transponder being hidden in a mush of intermodulation from the
others?

Cheers,
David

Peter Benney <tugboat@...>
 

The B2C2 card is purely digitial, so that doesn't
help, I can't find the part number for the tuner, and the chip next
to it is hidden under a heatsink!
David,

I think this might be it.

http://www.semiconductors.philips.com/pip/TDA8060ATS_C2.html

Peter

David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

--- In MSG-1@..., "pa3aod" <harms@a...> wrote:
Hi David,

I found some info on the WEB about the B2C2 chip(and software),
look at the following web-pages www.bbti.us and www.b2c2.com.

Bert PA3AOD
Thanks, Bert. I'd found those pages later by searching on B2C2. I
got an outline data sheet on the main chip on the card (FlexCop) and
on the "TechniSat" card (which seems to actually be a B2C2 card).
the plot thickens!

I am trying to get a better undertsanding of how the system works,
and what the so-called quality indicator means. At least in the
data sheet they talk about power (dBm) into a 75 ohm impedance, so I
am on familiar ground there. I haven't yet worked out from the
Eb/No threshold tables whether the 2.3 or the 2.6B is the more
sensitive card!

Cheers,
David

chip: <http://www.b2c2.com/docs/flexcop.pdf>

card:

<http://www.bbti.us/download/documentation/Sky2PC_Product_Specificati
on.pdf>

(beware of URL wrapping)

David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

I think this might be it.

http://www.semiconductors.philips.com/pip/TDA8060ATS_C2.html

Peter
Not convinced! The package is wrong.

But the two ICs in the tuner are SL1925 (zero-IF demodulator) and
TSA5059 (2.7GHz synthesiser). Perhapss the chip outside the tuner
does the analog to digital demodulation? The FlexCop II chip is
defined in the data sheet. The data sheets for those chips makes
fascinating reading.

Cheers,
David

Alan Sewards <alan.sewards@...>
 

David,
Looks as though the 2.3 card is the more sensitive, taking the 1/2 at
27.7 Ms/s figures, by about 1 dB.

Best regards - Alan

----- Original Message -----
From: "David Taylor" <david-taylor@...>
To: <MSG-1@...>
Sent: Monday, November 10, 2003 3:20 PM
Subject: [MSG-1] Re: Definitions and questions!


--- In MSG-1@..., "pa3aod" <harms@a...> wrote:
Hi David,

I found some info on the WEB about the B2C2 chip(and software),
look at the following web-pages www.bbti.us and www.b2c2.com.

Bert PA3AOD
Thanks, Bert. I'd found those pages later by searching on B2C2. I
got an outline data sheet on the main chip on the card (FlexCop) and
on the "TechniSat" card (which seems to actually be a B2C2 card).
the plot thickens!

I am trying to get a better undertsanding of how the system works,
and what the so-called quality indicator means. At least in the
data sheet they talk about power (dBm) into a 75 ohm impedance, so I
am on familiar ground there. I haven't yet worked out from the
Eb/No threshold tables whether the 2.3 or the 2.6B is the more
sensitive card!

Cheers,
David

chip: <http://www.b2c2.com/docs/flexcop.pdf>

card:

<http://www.bbti.us/download/documentation/Sky2PC_Product_Specificati
on.pdf>

(beware of URL wrapping)



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David J Taylor GM8ARV 🏴󠁧󠁢󠁳󠁣󠁴󠁿 🇪🇺
 

--- In MSG-1@..., "Alan Sewards" <alan.sewards@c...>
wrote:
David,
Looks as though the 2.3 card is the more sensitive, taking the
1/2 at 27.7 Ms/s figures, by about 1 dB.

Best regards - Alan
Yes, that was the way I read it as well. I just didn't want to
think that the card I had just replaced was actually better than its
replacement! Presumably this means that you need at least 1dB
greater SNR with the newer card (or USB version) than with the older
card for the same performance. Perhaps it isn't that simple....

Cheers,
David

Guy Martin <agm@...>
 

Haven't checked the maker's site myself but do they offer tech support by e-mail, might be worth a try.

Cheers, Guy

----- Original Message -----
From: David Taylor
To: MSG-1@...
Sent: Monday, November 10, 2003 5:29 PM
Subject: [MSG-1] Re: Definitions and questions!


--- In MSG-1@..., "Alan Sewards" <alan.sewards@c...>
wrote:
> David,
> Looks as though the 2.3 card is the more sensitive, taking the
1/2 at 27.7 Ms/s figures, by about 1 dB.
>
> Best regards - Alan

Yes, that was the way I read it as well. I just didn't want to
think that the card I had just replaced was actually better than its
replacement! Presumably this means that you need at least 1dB
greater SNR with the newer card (or USB version) than with the older
card for the same performance. Perhaps it isn't that simple....

Cheers,
David



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Timestep <Information@...>
 

From: Dave Cawley
Timestep Dartmouth England
e-mail Information@...
Web site http://www.Time-step.com
Tel. +44 (0)1803 833366
Fax. +44 (0)1803 839498

You just can't believe specifications, it probably says +/- 1dB somewhere,
or if not, what is the tolerance ? And anyway, manufactures have been known
to just invent figures, who can prove them wrong, or right ?

Dave