Dr Peters,

After suggesting the sideband method I began researching how.  It =
appears doing this digitally is a bit more complex than anticipated.  I =
did find that people in other fields such as ultrasound are using a =
Hilbert transform to produce the information.  I don't know what =
obstacles this would involve as to sample rate limits or translation to =
the extremely low frequencies from the MHz ranges they are using.   It =
looks like an interesting topic for winter night study.  AmaSeis can =
export the FFT of a segment of data as a starting point or an FFT =
followed by the Hilbert transform could be coded directly once all the =
limitations are known.

I wonder if an analog demodulator could be added to the seismograph =
using the microseism frequency of a second instrument as a continuous =
tuning device for the carrier wave.

Randy=20







Dr Peters,
 
After suggesting the sideband method I =
began=20
researching how.  It appears doing this digitally is a bit more =
complex=20
than anticipated.  I did find that people in other fields such as=20
ultrasound are using a Hilbert transform to produce the =
information.  I=20
don't know what obstacles this would involve as to sample rate limits or =

translation to the extremely low frequencies from the MHz ranges they =
are=20
using.   It looks like an interesting topic for winter night=20
study.  AmaSeis can export the FFT of a segment of data as a =
starting=20
point or an FFT followed by the Hilbert transform could be coded =
directly=20
once all the limitations are known.
 
I wonder if an analog demodulator could =
be added to=20
the seismograph using the microseism frequency of a second =
instrument as a=20
continuous tuning device for the carrier wave.
 
Randy