I think the general idea is that some signals have no carrier that a PLL could lock onto. The FLL Band-Edge centers a signal using the shape of a specific signal (the matched filter being used).
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