FLL Band-Edge

[Kristoff]

Hi all,


I have been reading some more on PSK demodulation.


One of the PSK signals I can easily pick and and is available 24h/day is 
the telemetry signal on QO100.
I found a flowgraph from Daniel Estevez that decodes the QO100 
telemetry, so I started examining how it works.

In that flowgraph (which for some reason I do not seams to find any 
more), the first block in the flow (i.e. right after downconverting and 
a AGC) is a "FLL_Band-edge" block.


Can somebody explain what exactly this block does?

I researching this, I found that it seams to shift the received signal 
slightly up in frequency (at least, that is what it did in my tests).

I tried reading the documentation, which kinds-of explain how it does 
work, .. but not what it does and why it is there.
Can somebody explain the purpose of a "FLL with band-edge filter" block?



Thx :-)

73
kristoff - ON1ARF