Symbol Rate (SR)

[cyberham]

Who can give an instant tutorial about symbol rate? Intuitively, it seems the higher the rate, the more the information being sent and therefore this should result in higher quality video? RTV, for example, is pretty ugly video and it has a low rate. Am I on track?

Added: Correction. I'll bet this is more to do with the idea that when a higher rate is used, there are more channels muxed together. For example, Galaxy 3C has several CCTV channels and it uses a high SR.

 

[madmadworld]

http://en.wikipedia.org/wiki/Symbol_rate

 

[Arion]

Who can give an instant tutorial about symbol rate? Intuitively, it seems the higher the rate, the more the information being sent and therefore this should result in higher quality video? RTV, for example, is pretty ugly video and it has a low rate. Am I on track?

Generally speaking that is true but it's not always the case as there are other variables involved. It also depends on what sort of compression scheme is used. You can have very high quality HD video being streamed at a symbol rate of less than 6000 using H.264 compression. Some of the satellite news gathering feeds stream very compressed high definition at less than a symbol rate of 5000. And some standard definition sports feeds are streamed in the 13000 symbol rate and look pretty crappy. Lots of different variables.

 

[cyberham]

Ok, then can't get much meaning out of just looking at the SR. Why is it that tps with lower SR values are supposed to be tougher to lock in? I've read that some receivers can't lock in a tp below SR XXXX.

 

[Arion]

Depends on the chipset of the receiver. There is very little content below 2000 sps.

 

[updatelee]

Defn depends on the demod. There are lots of things done by a demod to help it find the correct freq/sr that work great on higher sr but hinder lower sr locking

UDL

 

[cyberham]

Depends on the chipset of the receiver. There is very little content below 2000 sps.

The lowest I can recall receiving is KTEL Telemundo with SR 2170 ks/s. My receiver spec claims capability down to SR 1000 ks/s.

 

[Bob2011]

The lowest I can recall receiving is KTEL Telemundo with SR 2170 ks/s. My receiver spec claims capability down to SR 1000 ks/s.

The lowest that I have scanned in was the religious station on 72w that has a SR of 1666.

Someone correct me if I'm wrong but I believe the issue with low symbol rate locking has to do with the speed of blind scanning and processor speed. There is too little data from the low SR for the receiver to interpret in that fraction of a second that it is a TV channel.

 

[pro96]

Couple of 1562 SRs at 113w and 116.8w

Posted Using The New SatelliteGuys Reader App!

 

[updatelee]

Its all done in hardware. The amount of data has nothing todo with it

UDL