Because the digital format (MPEG) is transmitted based on the differences between video frames, much less info needs to be sent each frame. For example, if the camera is shooting a newscast and the camera is steady the only data being transmitted is the newscasters moving face, the background doesn’t need to be transmitted over and over because it’s not changing.
This “compression” and “multiplexing” allow several channels (usually 3 or 4) to share the same transponder.
Thus 32 transponders can carry 200+ channels.
So, in real world, when you are flipping through transponders looking at their signal strength you are looking at the signal strength of 3 or 4 channels combined. You will notice that with a single LNB when you scroll through the transponders only the even or odd transponders have good signal. The other set is not being used. With dual LNB’s one LNB reads the odd transponders and the other reads the evens. All transponders are being used thus allowing twice as many channels to be received.
What transponders are being “read” (even ones or odd ones) is decided by the “polarity”. Left-hand polarity (even transponders) is selected if the LNB is receiving 17 volts from the receiver through the cable line and right-hand polarity (odd transponders) is selected if the LNB is receiving 13 volts from the receiver. You can check this by using a voltage meter on the cable at the dish. No reading or a voltage reading other than 13 or 17 is usually an indicator of bad cabling, connections, a “cable type” splitter in the cabling somewhere or a faulty receiver.
With Dish 500 you will see that when you are selecting the satellite at 119 degrees on the signal meter screen you will get “wrong satellite EchoStar 110” or some such indicator on every other transponder. Then if you switch the signal meter to reading 110 the opposite will happen. This is normal and good. Not good is if it stays on “unrecognized satellite” or says wrong satellite on all transponders. That means you are pointed wrong.
Hope this helped, feel free to email me at (-REDACTED-)
> Try asking onetec. He's the dish wizard.
>
> > I just started working as a satellite instatller. I am looking for information on some or any technical issues reguarding Dish Network. Particullary Transponders.
> > Any advice appreciated.
