Strength/Quality in % - what does it really mean?

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Just looking at the reading of various STBs I have, and the TBS 5922 connected to my PC.
The user interfaces generally describes the incoming signal in terms of "strength" and "quality".
And it gives the readings in percent.
Not dBuV or MER or anything absolute (as on a meter); no it's percent.

...of what?
Some arbitrary level?
The max the receiver can handle?
Of the max-min range of the tuner input after AGC has been applied?

I am guessing that last part, in which case it says almost nothing about actual signal strength (i.e. not very useful), and quality - what's that?

Can someone with a datasheet or driver knowledge explain what these terms mean, and how they can be used for proper comparison of reception...? (If at all?)
 

Captain Jack

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I can only answer this in terms of Vu+ receivers' measurement and that is SNR/quality is 100% at 16.2dB. It actually works out the SNR from % (yeah, I know) so it's not a 'real' measurement - more pseudo than anything.
 

rolfw

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In real terms as the boxes are relatively cheap, they are not calibrated, so actual C/N, MER and accurate signal strength readings are not really possible, not convinced about many of the so called professional meters being hawked around in the £300 region, but then again, they don't need to be that accurate.
 
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In real terms as the boxes are relatively cheap, they are not calibrated, so actual C/N, MER and accurate signal strength readings are not really possible, not convinced about many of the so called professional meters being hawked around in the £300 region, but then again, they don't need to be that accurate.
True.
But let's assume this is for pointing and optimising a dish (what else is there a use for on a consumer device?).
Absolute field strength is useless unless calibrated.
Relative field strength would be a good start, at least you can compare different readings (optimise the poiting of the dish). So a consistent dB reading from some reference point would be a really good start.
Of course, this is made more complex if the field strength is not measured before the auto-gain circuit in front of the A/D converter.
But S/N, and i suspect also C/N ratio is probably a digital figure, so why not state this in dB?
And MER and BER are surely digitally derived figures.

But in all cases, % is completely meaningless, unless you clearly know what it is a percentage of.

However, I suspect that the prevalence of % figures in the softwares are due to the APIs of the chipsets expose the signal strength and quality readings as percentages. Application programmers probably just pass the information on, without making any more specific sense of it...
 

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% is probably used on consumer devices simply because they are more user friendly. An average person will not know what dB measurement is good... And do you remember signal 'quality' being reported in hex(!) on Nokia 9600 receivers with DVB2000 on it?
 

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Yeah, my DrHD F15 shows quality readings in dB (20dB being the max) but the Technomates, which use pretty much the same hardware, show the quality readings as a %age.
 

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Latest models technomate f3/5 and 5402m3 show signal in dB as well.
 

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Try 5922 with my CrazyBDA driver. Level(%) = 100+ RFLevel(dBm), Quality(%) = SNR *5.
100% compatible with my StreamReaderEx-BDA 1.2.0-1221+ (engine for CrazyScan, TSReader streamreader-proxy source, EBS Pro and etc)
Does that mean that the drivers actually give you readings in dBm?
Nevermind that they may be uncalibrated, that sounds like it would be a nice thing to have as "option" in the applications...

Will try your BDA driver tomorow, thanks for sharing.
 
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