Sep. 26, 08 daytime

Gate Delay Test#1

The difference of data1 and data2 is:

-------------------------------------channel-2------channel-5

data1 gate delay------------------0--------------13us

data2 gate delay----------------~1us-----------16us

No dead-time and background correction.

But either data1 or data2's channel 1 doesn't have delay (gate is always turned on). Since two data are not taken under exactly same atmospheric condition, their differences might be due to atmosphere. So the comparison of two data's channel-1 is used as a reference.

This experiment is suggested by Mike. The purpose is to investigate if the previous data without gate delay (use constant gate) have nonlinear behavior at initial bins. The retrievals of our data below 1km are not correct. We don't know if it's due to aerosol or due to nonlinear signal. We will particularly focus on the analog signal because the near-range retrievals are always made by analog signal.

Conclusion is:

• 1)For channel 2 of mini receiver, data1 and data2 behave the same. This means, it doesn't matter if there is a delay. No delay, you will see a saturation (exceeding licel limit) at initial bins, but the signal after that saturation is just the same as the signal you turn off the gate at the saturation period.
• 2)The ratio of data1/data2 behaves differently for photoncounting and analog, page 8 and 9. One is decreasing and the other is increasing. I expect data1/data2 is slightly increasing due to stronger SIB of data1 since data1-channel5 has less gate delay. But I don't understand why analog of data1/data2 decreases with range at 2.5-5km. The analog and photoncouting data record the same signal.