From naranjo Tue Nov 16 00:40:45 2004
Date: Tue, 16 Nov 2004 00:40:45 +0000
To: michael.loughlin@ukaea.org.uk, APX077@coventry.ac.uk,
        nigel.hawkes@npl.co.uk, colin.murray.01@bbc.co.uk
Cc: puherman@ritva.physics.ucla.edu, camara@physics.ucla.edu,
        shopkins@scs.uiuc.edu
Subject: BBC 03 follow-up 2/3 - PILL
Reply-To: Brian Naranjo <naranjo@physics.ucla.edu>

bbc_03_pill.pdf
===============

2262 Strong Triggers - Pill
---------------------------
These are the first 16 of the 2262 "strong shock" triggers
used in final BBC 03 analysis.  Each waveform consists of
a pure 25 kHz drive signal followed by the shock wave,
containing mixed frequencies as high as 700 kHz, arriving 3 ms
into the waveform.

Good Triggers
-------------
I analyze each pill waveform as follows:
 1. FFT to frequency space
 2. apply trapezoidal [40 kHz, 1 MHz] bandpass filter
 3. FFT back to time space
 4. discriminate leading edge of shock wave for segment timing
      - if the timing isn't within +/- 200 us of the hard trigger,
        the trigger is said to have bad timing.
 5. calculate a smoothed power profile:
      - calculate power |V_i|^2
      - FFT to frequency space
      - apply Gaussian convolution in frequency space
      - FFT back to time space

The smoothed power profile for the first 32 strong shock
triggers is shown.  Compare with waveforms on the previous page.


417 Weak Triggers - Pill
------------------------
417 of the original 3050 triggers had good timing but small
shock wave signals.  Shown are the first 32 events whose power profile
integrated over [0, 1 ms] was below a chosen threshold.  Typically,
the high frequency shock signal quickly decays on the order of
tens of nanoseconds, but then the drive signal slowly swells up
and persists for the remaining 5 ms.  The sonoluminescence guys
can provide better insight into why this happens.  My next email
will contain a complete analysis of these 417 events.

Bad Triggers
------------
The most common instance of bad timing is "LATE_TRIG", where
the hardware trigger fired more than 200 us after the software
trigger fired.  The "WEAK_SHOCK" events correspond to waveforms
on the previous page.

Brian
