Signal Strength and Signal Quality

[cwsat]

I have been sourcing and testing various LNB’s on my dish, some new, some old tried and tested to see how they perform.

I have noticed on many transponders, mainly mid to high powered, the 0.1db’s like the Technomate Gold for example out perform my Inverto Black Ultra on signal quality.

On pretty much every Sat and transponder, the Black Ultra 0.2db displays a better signal strength, on the meter and receiver.

I have always been under the impression quality is key but with a weaker signal, surely you get breakup quicker?

Heavy clouds, rain etc will attenuate a weaker signal and cause breakup on a weaker signal with better quality?

 

[7mdish]

Please remember that we are digital.
In the good old analog era, signal strength was the first parameter to consider.
Today, in the digital era, one of the most important parameter is BER (Bit Error Rate). Lower BER means better quality.
A weaker signal but with a better BER could be better than a stronger one.
If the signal is weak due to rain or satellite signal strength, BER become massively important.
So, choose the LNB with the best signal quality, not the best strength.
Also, remember that LNB noise figure is not always specified in the best way.
Values of 0.1 or 0.2 are almost impossible to reach. Thermal noise, in Ku band, is around 0.5 dB. So what is the reason to make LNBs with 0.1?
And, those very low values (if exist, I doubt....) are probably taken in a single point of the receiving band (the best one), and they are not flat in the entire band.
I believe that values around 0.6-0.7 from the professional PLL LNBs are more realistic.
Finally, look firstly at the signal quality instead of signal strength and you do not wrong.

 

[cwsat]

Thanks for the info @7mdish

Time to workout which LNB performs the best quality wise across the arc then!

 

[rolfw]

I stopped using black Ultras some years back because of the signal quality issue, the mid range LNBs like Triax outperformed them across the spectrum and proved to suffer less problems. As I install IRS systems, the most crucial element of the installation is the MER and BER of the weakest frequencies, signal strength from the dish merely needs to give me a reliable margin in case of bad weather, the amplification at the head end deals with system wide distribution strengths.

 

[cwsat]

I stopped using black Ultras some years back because of the signal quality issue, the mid range LNBs like Triax outperformed them across the spectrum and proved to suffer less problems. As I install IRS systems, the most crucial element of the installation is the MER and BER of the weakest frequencies, signal strength from the dish merely needs to give me a reliable margin in case of bad weather, the amplification at the head end deals with system wide distribution strengths.

I had the v1 / mk1 long necked ultra on my 85cm Gibertini dish and the TM1-Gold out performed it apart from 8w and 26e which I lost - just got break up.

I sold it on and kept the TM-1 Gold, then upgraded the dish to a 100cm dish - back came 8w and 26e.

I thought I would give the Black Ultra Mk2 a go and it's producing very similar results to the 85cm with the TM-1 on it, on the 100cm dish.

I have a good friend, been in the sat trade donkeys years, with a Channel Master 1.2. As professional an installation you will find, we know the dish is absolutely spot on, with a black ultra mk2 quad fitted. On the meter, it's slightly edging my dish but there is hardly anything in it. My 100cm isn't a high quality Gibertini or Channel Master too.

I read something which confused me a little, which one of you will be able to confirm.

'With a digital satellite signal, signal strength is actually the strength of the signal from the LNB to the receiver, not the actual satellite signal itself'

Is that correct? Doesn't really make sense to me that.

 

[rodscha]

Hello ,I have a question on signal strength.
In Carcassonne south France with a 120cm dish,Schwaiger single LNB,
I have a reception of BBC HD that varies throughout the year...seasonal variations.
Right now (july,sunny weather) I get Strength=84% and Quality fluctuates between 42 and 58,several times a second.
This fluctuation increas with a weaker signal (as before Coronation,I got 10 %to 35%,hardly watchable....or nothing mid-day
As signal strenthen,the Quality nears the Strength,but never equals it. Will climb to S=90/Q=78(BBC 1 & 2 on the Manchester signal;(3&4 come in weaker on their unique HD frequency )
However a different story with CNN ,which is hyper-stable and yields S=79% Q=85%, throughout year ,any time of day
I know it s the Pan European ....but why a higher Q than S?
Other pan-european,such as PTV,yield S=79 /Q=76 ,stable any time.

I need to re-point,my priority being BBC 1,2,3,4.
And the strongest I now get (within the UK beam) are the channel 5 bunch...(which I can live without,lol!!)
Ch5 HD yields S=83,Q=73
when bbc 3 and 4(children's now) are dead.Will be back later after 6pm
Repointing:azimuth or height? or just leave it as it stands?

 

[cwsat]

Hello ,I have a question on signal strength.
In Carcassonne south France with a 120cm dish,Schwaiger single LNB,
I have a reception of BBC HD that varies throughout the year...seasonal variations.
Right now (july,sunny weather) I get Strength=84% and Quality fluctuates between 42 and 58,several times a second.
This fluctuation increas with a weaker signal (as before Coronation,I got 10 %to 35%,hardly watchable....or nothing mid-day
As signal strenthen,the Quality nears the Strength,but never equals it. Will climb to S=90/Q=78(BBC 1 & 2 on the Manchester signal;(3&4 come in weaker on their unique HD frequency )
However a different story with CNN ,which is hyper-stable and yields S=79% Q=85%, throughout year ,any time of day
I know it s the Pan European ....but why a higher Q than S?
Other pan-european,such as PTV,yield S=79 /Q=76 ,stable any time.

I need to re-point,my priority being BBC 1,2,3,4.
And the strongest I now get (within the UK beam) are the channel 5 bunch...(which I can live without,lol!!)
Ch5 HD yields S=83,Q=73
when bbc 3 and 4(children's now) are dead.Will be back later after 6pm
Repointing:azimuth or height? or just leave it as it stands?

How receivers interpret a signal can be strange.

I have seen significant signal strength and quality improvements on a meter, yet on the receiver no improvement.

Some LNB's perform differently across the frequency range too.

The weather / Sun has been known to cause issues in Spain with Astra 2 reception.

I believe the basic Freeview lite channels are around at 27.5W, biss encrypted, which some expats have been using in Spain to get around the Astra footprint changes. Unfortunately no encryption chat on here though.

 

[jeallen01]

U PMd me to tell me not to call people mate as it could.be offensive ..pipe down mate. Joker

How receivers interpret a signal can be strange.

I have seen significant signal strength and quality improvements on a meter, yet on the receiver no improvement...

Probably because the receiver was already giving its "best performance" with the SS/SQ levels from the original LNB, and thus that further improvements thereof could not make any difference.

 

[rodscha]

My main question is,how should I interpret a fast up-and-down varying "quality" bar,like the "10 to 35" I get when the UK beam is weak?
I should expect a stable "25" green bar ,and maybe a "50" red bar below it
& I get an "85" red bar with the jumpy "10 to 35" green bar below it....and no picture or only shreds.
Or,a "20 to 45" jumpy one and some picture... until either a meltdown,or a better signal. No trees etc in sight.

My receiver is a Comag which works fine,very stable device.Double tuner.

 

[rodscha]

receiver is a Comag which works fine,very stable device.

 

[cwsat]

Probably because the receiver was already giving its "best performance" with the SS/SQ levels from the original LNB, and thus that further improvements thereof could not make any difference.

My main question is,how should I interpret a fast up-and-down varying "quality" bar,like the "10 to 35" I get when the UK beam is weak?
I should expect a stable "25" green bar ,and maybe a "50" red bar below it
& I get an "85" red bar with the jumpy "10 to 35" green bar below it....and no picture or only shreds.
Or,a "20 to 45" jumpy one and some picture... until either a meltdown,or a better signal. No trees etc in sight.

My receiver is a Comag which works fine,very stable device.Double tuner.

Do you have a meter?

The leaping bar is the receiver most probably losing lock and then regaining it as the signal is so marginal.

You could do with trying a meter, see if the quality leaps about on that too.

If it does, short coax cable into the LNB, if it still does it, try another LNB.

 

[rodscha]

Thank you very much,I had an inverto black before,lasted only over a year,it had the jumpiness when low propagation occured.
It died under hot sun. The present Schwaiger seems more resilient.
What would the "new" super-Inverto be ,nowadays?

 

[cwsat]

Thank you very much,I had an inverto black before,lasted only over a year,it had the jumpiness when low propagation occured.
It died under hot sun. The present Schwaiger seems more resilient.
What would the "new" super-Inverto be ,nowadays?

The new black ultra is very similar to the old in performance, just the neck is shorter.

I am not overly impressed with mine although on feeds it does seem to perform well.

My Golden Media 0.1db LNB matches it.

I would try a meter if you can and see if that jumps about.

 

[rodscha]

I was wondering whether it could be an error in pointing