OTHER Transponder Signals- Why the Difference in % Quality?

[spongella]

Not sure if this question belongs here, but it is somewhat related to receivers. My apologies to the forum members if I put it in the wrong place.

After many years of watching Ku FTA TV I've always wondered why different transponders on the same satellite are received with different % quality. Not talking about a few per cent, sometimes there's a great difference. Is it because certain channels don't need that much output power (wattage) from the satellite, or is it a matter of how much a company is willing to spend to get their signal out? Does location matter? Does it depend on the type of beam (spot, hemispherical, panamerican)? Maybe bandwidth and symbol rate affect the amount of transmit power needed from transponder?

Since satellites are solar powered, I'd imagine that there's only so much power (wattage) to be divvied up among the broadcasters using that satellite.

With all the knowledgeable folks on this forum am sure someone has an answer.

Thanks.

Sponge

 

[Magic Static]

There are a lot of factors and many have been discussed.
http://www.satelliteguys.us/xen/search/384818/?page=2&q=transponder+power&o=date
Look at posts from Titanium. He has a lot of technical background

 

[Titanium]

The signal quality of each transponder is affected by many variables as you mention. Add to the list, adjacent satellite interference, reflector, feed, LNB and receiver characteristics.

A link budget is developed for each carrier that is based on the downlink requirements for maintaining a margin of signal strength for xx.x% reliability. This includes the amount of money the broadcaster wishes to spend, bandwidth, dish size, efficiency, prevailing weather conditions, uptime, etc.

Example: if the target downlinks have large efficient dishes/feeds and generally great weather, the link may use a higher FEC, less bandwidth and lower power to achieve acceptable up-time. Downlinks operating outside of the link budget calculations will experience lower quality levels and reduced up-time.

 

[Mr Tony]

I also assume it has to do with how many folks they "want" it to see and what size dish is at the receiving end?

 

[spongella]

Thanks for the input guys. The other thing that I wonder about is how a satellite manages spot beams, hemispherical beams, etc. Is this done by pointing the satellites's antenna toward a specific area? How do they manage a spot beam, that is, how can they specifically target an area so narrow? Or do they do it by software/hardware on both the transmitting and receiving end.

Interesting stuff.

Sponge

 

[srbspikey123]

does anyone know what disq is

 

[FTA4PA]

does anyone know what disq is

Welcome srbspikey123! Do you mean Diseqc? If so read this http://en.wikipedia.org/wiki/DiSEqC and this http://www.satelliteguys.us/xen/threads/diseqc-1-0-1-1-1-2-1-3-whats-it-all-mean.133444/