Signal Strength vs Signal Quality

updatelee

updatelee

SatelliteGuys Pro
Jul 22, 2006
1,604
111
CFB Edmonton
So based on that link I must be at 600% quality right now ? even though Im actually 0.2db below lock threshold ?

% is relative based on a position within a min/max scale. db is NOT relative, its a proven method of measurement. repeatable across any receiver.

Im not going to argue this anymore, anyone that knows me knows I know what Im talking about. If you believe Im wrong, prove it. Everyone messes up, Ive been proven wrong before. Your turn, you'll have todo better then that last url though.

UDL
 

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climy

climy

Well-Known SatelliteGuys Member
May 8, 2010
26
1
west
Your right that was a bad example of a conversion table for db--but it's possible to have a lookup table in the STB signal quality code graphic display page--all a guess on my part however. And not questioning your knowledge. You seemed to be barking up the wrong tree because the point I defended was the OP comment of percent what it meant. I used my example C-band and Ku band on the Reelbox as an example and clarify that FTA receivers use some relative scale in percent for signal quality which is evident from the OP and my example. A calibrated tool-tuner or instrument will display db. Speculating again, the manufacturer Reelbox, et al. tuners get into "trouble" using terms, quoting from the data sheet: "STR (Strength): Gives signal strength as a percentage. A minimum level of 60% is required to ensure a quality signal. SNR (Signal-noise-ratio): Gives signal noise ratio as a percentage. Providing the signal strength is at least 60%". That was on the datasheet of the tuner and the basis of my discussion/example. I appreciated your screen shot. What application/software is that?
Climy
 
updatelee

updatelee

SatelliteGuys Pro
Jul 22, 2006
1,604
111
CFB Edmonton
Its updateDVB. An opensource Linux application Ive written, in conjunction with v4l-updatelee (my fork of the v4l media tree) provides additional functionality like spectrum graphs, IQ plots, and blindscan for various PC satellite/atsc/ and qam tuners. It also does signal parsing for DVB, Digicipher II, atsc and qam signals. It will allow you stream specific PIDS through TCP.

UDL
 
R

richyrich

SatelliteGuys Pro
Sep 2, 2008
480
20
dead
Hold on a second; i m lost. EX: Odd and even number expresses a 2 dim; an odd number; an even; and another even will express a 3 dim number; but to express a 4 dimensional number (with its limits) which is satellite signals; how do they calculate a picture? Time is a number; odd or even; much of one and another. Percentages do something; they set limits first; and the odds are just rounded off in the fine dropdown of the limits it rounds off to.


if a percentage is a number then what it answers is still 2 dimensional; basis of 2 different numbers compared. Is it at the limits? With all four dimensions of the receiver already set to a limited value; then is it a real number anyway; percent of a number; or how fine the number is? This also makes the limit what the percentage is talking about. And when what amount of time it must take this one sixtyth of a second ; processors and daq's can rule by roosting by then saying that is it; that it is, and it is final.
 
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FaT Air

FaT Air

HOA Free Zone
Feb 27, 2010
6,668
914
97W 48N
SNR - Signal to noise RATIO
BER - Bit error RATE , also a RATIO.
Ratios themselves cannot be described by, or as, a percentage.**

A CHANGE in SNR or BER can be described as a percentage. But only if one first knows the SNR in db. Or the BER actual values.
Expressing SNR or BER as a % is some arbitrary calculation programmed by the firmware developers.

Q is also an arbitrary unit, determined by the firmware developers, to give an indication of how well their design is coping with demodulating the signal tuned. Being arbitrary, different receivers will show different "Q" when on the same dish/LNBF.
My Pansat will show a particular TP as Q32 and the S9 will show Q70.

**Well BER could be described as a percentage. With 0 errors being 100%(something that rarely happens IMHO)
There's no way SNR could be.
 

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