R
Rene Tschaggelar
- Jan 1, 1970
- 0
While I think to have understood what phase modulation is
about, the finer details of implementation have escaped me.
The phase shift of a signal compared to a reference signal
can be coded by a few bits depending on the number of phase
steps. This is understood.
However what happens when the reference signal is not available ?
This can happen when the transmitting and/or receiving side
has a generator that is not stable to a radian per day,
PLL-ed up from some lousy temperature dependent quartz with
some jitter on it.
How am I expected to get my bits back ? Running a PLL would
get me a bitstream as the derivative of the phase or so.
However since lacking the reference signal the received coding is
arbitrary, just a phase differential. I'd have to check all
possible combinations and somehow select the right phase.
Any hints, where I can gleam the phase-zero from ?
And how can I preserve the phase-zero over time.
Rene
about, the finer details of implementation have escaped me.
The phase shift of a signal compared to a reference signal
can be coded by a few bits depending on the number of phase
steps. This is understood.
However what happens when the reference signal is not available ?
This can happen when the transmitting and/or receiving side
has a generator that is not stable to a radian per day,
PLL-ed up from some lousy temperature dependent quartz with
some jitter on it.
How am I expected to get my bits back ? Running a PLL would
get me a bitstream as the derivative of the phase or so.
However since lacking the reference signal the received coding is
arbitrary, just a phase differential. I'd have to check all
possible combinations and somehow select the right phase.
Any hints, where I can gleam the phase-zero from ?
And how can I preserve the phase-zero over time.
Rene