What is Strenght & Quality, the mystery unlocked!

Strength - Your receivers strength meter will accurately show the strength of THE satellite(s) your dish is pointed or aimed at. Said another way, if your dish is mis-aimed and pointed at a satellite you did not intend to be pointed at, it will STILL indicate strength, as this is simply an indication that you are pointed at SOME satellite. It is very important that you are pointed at the desired satellite, this can be verifed on your receivers satellite setup screen, the screens popup window MUST indicate the desired satellite. Once on the desired satellite, peak the dish referencing the Quality meter.


Quality - is the amount of processed digital signal that has been decoded by the receiver, and are to us are the Video and Audio signals. The software (our .bins) does the processing and decoding of the digital signal. This software is usually provider scheme specific, with internal changeable security codes (keys). The "Quality" is the digital hits and misses after the receiver decode. It is indicated as the reciprical of the error rate, therefore, the lower the error rate, the higher the quality of the signal.
When tuning receivers for best signal, Quality is the indicator that you want to use, as it is the only one that the receiver uses. Quality will be different from receiver to receiver Manufacture/Model. I have taken one receiver and it indicated Q=65%, removed it, installed another receiver and got Q=87%.


Simularly;

Strenght; could be compared with the engine revolutions in our car. The tachometer indicates the quanity of revolutions that our engines are turning, as the Strenght meter indicates the quanity of signal.

Quality; Like the automatic transmission in our cars, it converts (processes) the engine revolutions into usable power that drives the car, and is indicated on our speedometer.

There has been much confusion and mis-information about Signal Strength and Signal Quality, and I want to try and dispel these myths and rumors to help testers use these two indications properly and effectively.
Signal Strength (SigS) - is little more than an indication of LNB output power - a good reference that your LNB is turned on and working, and that your STB output power, cabling, switch, and connectors are all OK. The SigS indication is only measuring as far away as your LNB, and That's it.!! Once you see a reasonably good SigS indication, make a mental note that your LNB and antenna system is working fine, and then FORGET ABOUT IT..!! DO NO USE IT FOR ANYTHING ELSE ..!!.

Conversely, if you have a low or no SigS, it's time to start looking for a bad LNB, poor or wet/corroded connections, damaged cable, STB output problems, etc. To prove this explanation, humor me and try this..: Connect a spare LNB to your receiver with a short RG6 jumper, turn on your receiver, and note the SigS and SigQ indications.. See how the SigS is relatively high, while the SigQ is low or non-existent.. put the LNB in your pocket and note that you still have the same relative SigS.. definitely *NOT* any indication that you are receiving a sat signal..(unless you have a very unusual pocket.!!)

Signal Quality (SigQ) - *IS* an indication that your dish/LNB setup is receiving a valid satellite signal from somewhere ...although not necessarily the bird you really want...SigQ is actually measuring a signal being received from a satellite 22,300 miles away. The absolute value of SigQ will be directly related to how well you point your dish, and align your LNB. Once you determine that it is, in fact, the correct bird, ONLY then is higher SigQ is always better..Tweak your dish and LN, to max SigQ for highest indication, which will ensure best viewing, and greatest fade-margin against weather and other occurances. Once you have Locked-On to a valid signal and have reasonable SigQ, then it is time to do a quick sat scan to verify what bird you have locked on to, and then move on with your receiver setup, etc...
Both SigS and SigQ are "relative" numbers.. In other words, they are not calibrated or referenced against anything in particular.. So, a 75 on one STB might read 48 on another box connected to the exact same antenna setup. I have personally witnessed this, and learned the hard way, not to trust absolute numbers.

DOs and DON'Ts

NEVER try to scan for channels before achieving a reasonable Signal Quality on your receiver.. It is futile to try and scan a satellite that you have not locked on to yet..It's like trying to start a car before putting gas in the tank.
NEVER use Signal Strength to try and align dish/LNB.. it's futile, since it only means that your LNB is working..
NEVER use Signal Strength and Signal Quality as absolute numbers.. What you are used to on one receiver might be totally unattainable for another user.. and what he is observing might seem low to you, but is totally maxed out on his setup by comparison.
ALWAYS use Signal Quaility to line up your dish and LNBs.. It is *THE* indicator that tells you you're on a valid satellite, and most likely the one you are trying to lock on to.
ALWAYS scan for channels after maxing your Signal Quality indication and verifying that you're locked onto the correct bird.
ALWAYS use the Signal Strength and Signal Quality indications as references for YOUR box.

Dispelling some of the misconceptions about Signal strength and Quality.

Signal strength “S”

This is not the signal from the satellite, it is the level of the signal from your LNB to the receiver, adjusting the dish to improve the “S” will do nothing to improve this, using a bigger dish also will do nothing, some of the things you can do to raise the “S” is to use better coax (RG-6 quad with a pure copper center conductor) or shorten the distance from the LNB to the receiver, one solid run of coax from the LNB directly to the receive is the best way to get the highest “S” you can, when you put ground blocks (needed) switches or splices inline you can drop the “S” 10% to 40% however this will not affect the signals “Q” that much.

Things that can affect “S”.

Bad or poor quality coax, this is the pipe that delivers the signal from the LNB to your receiver, a poor quality coax is like a leaky hose, the more leaks the less water, the same with coax, the more connections, poor shielding, connections to other devices or a copper plated center conductor can lower the signal to the receiver.

Poor quality or wrong type of coax.

The cheaper the coax the more loss it has, this is because they cut back on the amount of shielding or thickness of the center conductor, coax made for CATV (cable) is not recommended for satellite systems, the signal used in CATV is from 40 to 900 MHz, the coax used for this is only rated for that range, the signal from the LNB is from 950 MHz to 2.5 GHz, the coax for CATV has a higher attenuation at the satellite frequency range and you get less “S” to the receiver.

Water.

This is not a good thing to get into the coax, switches or connectors, if you have a coax with a copper plated steel center conductor the water will cause it to rust, this will cause the signal to drop or go away all together, water in the coax can cause all sorts of problems.

Kinked coax.

If the coax was kinked during installation it can cause a loss of “S”, the distance between the center conductor and shield is very critical, kinking the coax will change this distance and change the impedance (75 ohms) of the coax or even short it out (no “S”) altogether.

PVC jacket of coax damaged.

If the PVC jacket is damaged or cracked it can let in water (not good) a nail in a coax staple can pierce the jacket and cause problems, the jacket is to protect the shield from corrosion due to water.

Signal Quality “Q”

The signal used in DSS satellites is digitally encoded and uses what is call Forward Error Correction, (FEC) this is a digital data program that is sent along with the digital video/audio programming to insure the final signal is error free (as possible) when the two signals are compared the FEC will correct any errors in the digital programming to insure it is error free. (bit substitution)

The level of error correction is measured as Bit Error Rate, (BER) to correctly measure the true BER you need some very special equipment, however the receiver has a special circuit in it to do almost the same thing, this circuit is what gives you your “Q” signal at the receiver, the higher the “Q” the lower the BER is, a “Q” signal in the 40 to 60 % range is still useable but will give you problems during rain and snow storms, a “Q” signal of 60 to 80 % is a good signal and if that is all you can get with your setup, its not worth the effort to get a 99% “Q” as you probably wont notice the difference, it will not improve your picture quality.

So if your have an “S” of 60 to 80% and a “Q” of 60 to 80% with your current setup and you have spent countless hours trying to get more it’s not worth the effort to keep trying.

Ways to improve “Q”.

Follow some of the guide lines in the section about “S”.

“Q” is low or fluctuating. Use a bigger dish, most satellite signals can be received on the standard 18” dish found on many homes today, how ever the further you go North or South from the center of the North American Continent the further outside you get from the prime footprint from the satellite your trying to receive, 95% of DN satellites are pointing at the US, BEV satellites are pointing at Canada, so if your in central or northern Canada you may need a bigger dish to receive DN satellites, if your in the US and trying to receive BEV satellites you may need a bigger dish.

Terrestrial interference.

This can affect “Q” and can come from anywhere, the signal from the LNB to the receiver is in the 950 MHz to 2.5 GHz range, anything transmitting close buy to your dish in this frequency range can affect the “Q”, this can be cell phones, cordless phones, routers, local WIFI signals and other things close buy or inline with your satellite dish.

Obstacle interference.

“Q” was good during the winter, now its dropped, the trees/bushes have their leaves back, this can reduce the signal to the dish, moving the dish to an unobstructed view of the satellite is one way to fixe this, the other is to trim the trees.

Building in the way.

No way around this if you can’t move the dish to a better position.

One other thing that can affect “Q” is if the dish is pointing to a satellite that is low to the horizon, (<20 degrees elevation) you have more atmosphere to go thru, excessive atmospheric attenuation can drop the signal to the dish by about 30%, so a satellite at 45 degrees elevation that has a “Q” of 80% in one area, could have “Q” problems if the elevation was 20 degrees at another location.