Quality ratios between satellites

satbadger

Looking at SatMans improved quality

http://www.satellites.co.uk/satellite/picture-members-setups-general-satellite-installations/130365-triax-td88-vs-fracarro-penta-85-a.html

I was wondering if there is a list of typical quality values that should be achieved for say 28.2E, 1W & say 30W or a ratio between them?
This might be handy to know so that you could check that the arc is being correctly tracked. I know it depends on where you are located but would be nice if there was a general value for the larger cities in Europe.
Id be interestested particuarly in sw London.

ditdahdahdah

I think that there are too many variables. Output power output of different satellites
variable slant path loses between satellite and receiver
size and gain of the dish
gain of the lnb
length and losss of the coax cable
sensitivity of the receiver
I expect there might even be others.

Topper

Whilst some could be included in dd's answer I would be more specific
uplink and downlink absorption due to
humidity
cloud cover
rain

accuracy of alignment
insertion losses for distribution system
also for wall plate terminator
dish/lnb tuning as well as all previously posted

all in all impossible to quantify and constantly varying

War does not determine who is right, it determines who is left!

Formerly toppervte33h
whose six pack has turned into a keg

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satbadger

Oh well sounded like a good idea when started the thread but I guess you guys are right, there are just too many variables

BombedOne

But some formula may be developed, to allow calculation of some Q mark from these variables.

ditdahdahdah

I would imagine that the proffessionals have long and intricate forulae, taking into account many variables. But would we know how to work them out, or even have the means or equipment to carry out anty measurements?
dddd

Huevos

It doesn't matter how many equations you do on a piece of paper it's not going to get your dish tracking the arc. But... getting the arc is child's play if you have a USALS motor. Check the mast is completely upright (90º). Set your lat on the motor mount. Zero the motor using the receiver. Put the dish on the motor completely straight and bolt it up tight. Don't move it again. Put your lat/long in the receiver. Send the motor to your nearest due south sat. Move the dish up and down, and move the motor around the mast left to right until you have the strongest signal from your "due south sat". That's it. Going to other satellites just confirms you followed the above steps correctly.

As for signal levels (depends on the receiver) you need -40dBm signal and 8dB C/N or better for a signal to be reliably watchable on an average receiver.

BombedOne

The only one partially reliable comparative value that can be roughly estimated by looking at receiver Q% is FEC/SR combination. Since most DTH systems use high SR (22000 to 27500 typical), things can be more easier, and only FEC should be noted. By my personal observations on various sats and receivers, I can roughly estimate, that 1X of Q on satellite with FEC 3/4, equals to 2X quality on satellite with FEC 7/8. Also it should be noted that receiver has AGC, so it may try to "compensate" at certain point the level of signal, and won't reflect it on Q reading.

If above text is too complex, here's shorter explanation:

Use your receiver on various sats, remember Q and signal on all of them, after some time, you'll develop own sense and skill to know, which Q% of signal is good for trouble-free tv on your receiver and which is not.

Huevos

BombedOne, that's interesting information but it's not going to tell you if you are accurately on the arc. The only way to know for sure it to pick 3 satellites (one east, one south and one west). Then set the dish up on an az/el mount. Choose one transponder on each sat. Point the dish at it and take a note of the signal and quality. Now set up your motor. If you are on the arc you will get the same reading on each satellite with the motor as you did with the az/el mount.