PSN-L Email List Message

Subject: Sideband information
From: "Randy Pratt" rpratt@.............
Date: Thu, 24 Dec 2009 11:31:51 -0600


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 

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