Calibrating ATI sonics.  (stripped from ATI manual)  Steve Oncley 2/8/94

The new ATI sonics have a built-in zeroing procedure.

Before doing this procedure, ensure that the sonic channels are not
spiking.  If they are:
1. Make sure both boxes and arrays are grounded to a good ground point.
2. Put zero chamber over a path
3. Attach a scope on TP1 and synch on TP2 (see diagram inside box).
4. Adjust C1 for best signal to noise
5. Adjust RP1 to have first peak less than 1 V and second peak greater
   than 6 V.  Replace transducers if this is not possible.

Zero procedure (repeat for all three axes):
1. Estimate the air temperature, usually by "cshow" on a nearby (in height)
   psychrometer.
2. Put zero chamber on path.
3. Enter code with rotary switch (01=u, 02=v, 03=w)
4. Toggle "Cal" switch downwards & back to center.  "Temp" light should go on.
   (I have found that sometimes it doesn't.  In this case, reset the sonic
   first by toggling "reset" downwards and back to center.)
5. Enter temperature (to nearest degree) with rotary switch.  Put "Bench test"
   switch in "Special Function" position if temperature is negative.
6. Toggle "Cal" switch downwards & back to center.  After 15 seconds, both
   "Cal" and "Temp" lights should go out.  If they are blinking, the 
   calibration must be repeated.

Note that the temperature in the zero chamber may not be the air temperature.
Best may be to leave the chamber out in the air (in the shade!) for a few
minutes before this calibration.

Also note that the chamber may "leak" in all but light winds.  It may be
helpful to put something more solid (foil, box) around it to block the wind.