Symbol Rates

wolsty

"Satellite Expert"
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My Satellite Setup
VU+ Duo, Humax IRCI5400z, Sony Bravia KDL-32EX403, 1.1m Triax, Technomate TH-2600 DiSEqC mount, Sony BDV-E280 Home Cinema system, ancient Logik Freeview PVR.
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Kernow
#1
Why do some receivers have symbol rates as high as 45000, whilst others go no higher than about 31000? Is there any advantage in having the greater range?

wolsty
 

rolfw

Believe it when I see it Admin.
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Berkshire
#2
It would seem that for normal viewing anything above 30,000 is pretty well unnecessary on most of the satellites using KU band, I guess that a symbol rate higher than that would be used for high quality single channel per transponder applications.

Rolf
 

Channel Hopper

Suffering fools, so you don't have to.
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A little less analogue, and a lot more crap.
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UK South
#3
Its all to do with the manufacture of the receiver

Some tuners have only one filter in them (the fiilter works in a similar way to the user as a bandwidth filter on analogue equipment - 18 / 27 MHz etc) to allow the receiver to filter out unwanted stuff

The ceramic filters of commercial or subsidised boxes are limited to the higher symbol rates of 18 - 45000 Ms/S and so cannot be used to receive the SCPC broadcasts - this is why the older receivers (and to some extent BSKYB stuff may not be good at finding everything, even though there are further restrictions in the firmware and OSG)

Newer receivers have a dual circuit of filters that has switching between the old limits and the new of 1 - 22 Ms/S

You will not see the switchover in operation, and there is no point in restricting the upper limit of 45 by the manufacturer as it would limit overall sales

There are some broadcasts up there that do have higher symbol rates than 300000
 

Channel Hopper

Suffering fools, so you don't have to.
Staff member
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My Satellite Setup
A little less analogue, and a lot more crap.
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#4
Typo - that should have been 30000

Just woken up and its not my usual keyboard
 

w hole

Regular Member
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uk
#5
Reminds me of that old Mony Python one :

I - HAVE - A - COLD!

W Hole ;~}
>
>Just woken up and its not my usual keyboard
 
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