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On board the T28 aircraft was a Hail Spectrometer. The probe output 1D data for ?all? of it's flights. The probe had an array of 128 image elements .9mm in size. For the 1D outputs, if say a particle were to block four consecutive image elements, then the system would record the top and bottom blocked diode as the size of the particle and output a sized particle based on that. There is no size dimension along the width of the particle or the direction of travel. Once the diodes were no longer blocked, then the probe would “?refresh?” and wait for the next particle to pass through. Because the probe was made for larger particles, it can be assumed that coincident particles are rare. However, in the event there were coincident particles, unless the probe knew to filter them out and ignore them, then an erroneously large particle could be recorded.
Here is an example of what the data file looks like,
Time is at 1 hertz, and the counts are in 1-14. Size ranges are,
- 01 : 0.40 - 0.50 cm
- 02 : 0.50 - 0.60 cm
- 03 : 0.60 - 0.70 cm
- 04 : 0.70 - 0.80 cm
- 05 : 0.80 - 0.94 cm
- 06 : 0.94 - 1.10 cm
- 07 : 1.10 - 1.30 cm
- 08 : 1.30 - 1.56 cm
- 09 : 1.56 - 1.86 cm
- 10 : 1.86 - 2.17 cm
- 11 : 2.17 - 2.61 cm
- 12 : 2.61 - 3.21 cm
- 13 : 3.21 - 4.00 cm
- 14 : 4.00 - 5.00 cm
The size ranges become more spread apart as the channels get larger since there are less large particles.