problem with this LIDAR program

[phy_mechanic]

This program is used to monitor LIDAR signal by a Transient Recorder.


When I set the strobe number of this program to larger than 1023, the signal that I get become very noisy, what is going on?


Please, any idea how to do it?
Phy_mechanic

[Kristen_K.]

Hi Phy_mechanic,

I took a look at your code, but could not run it because I do not have the Licel specific functions.  Nothing jumped out at me.  Does the noise only appear above 1023?  What does the strobe number represent?  Can you attach screen shots of the non-noisy and noisy signals?  Does the enviroment change when the strobe number gets above 1023? Noise can come from a number of different sources so the more information you can offer the better.  thanks!

Kristen H.

[phy_mechanic]

 Hi Kristen H.,

Sorry, I have make a mistake, the noise only appear above 1025. From the manual, it said that "The horizontal scale is given in bins. The number of displayed bins is controlled by the Strobe Number control. This number should not exceed the memory length of the transient recorder; for a TR-xx-80 this would be 8190 and for a TR-xx-1 60 16380 bins.” As the screen shot shown, when the strobe number excess 1025 the signal already very noisy (the strobe number not excess 8190 or 16380). So I don’t know what happen.

Thank you for your help!

Phy_mechanic

[Kristen_K.]

Hi phy_mechanic,

That is curious behavior.  The manual you quoted from...is there an electronic copy available online somewhere?  I'd like to read more about the strobe number since that seems to be the thing that has to change to cause the behavior.

Kristen H.

[phy_mechanic]

Hi Kristen H.,

The electronic copy of the manual was attached. But there are only a few lines talking about the strobe number.

Thank you for your help!

phy_mechanic

[johnsold]

Look at section 6.3.3 of the manual.  It talks about configuring the transient recorder(s).  Is it possible that the configuration is set for the smaller number of samples, making the front panel Strobe setting irrelevant?

I do not know anything about the instrument, I just spotted this in a quick glance at the manual. 

Lynn 

[Kristen_K.]

Hi phy_mechanic,

A couple more questions:  The vertical axis looks like is "# of photons counted"  and the horizontal axis is bin # 1, 2, 3, etc.  What determines a photon goes into a particular bin?  I assume it is acting like a histogram. It seems like bins 1026 and above have a many more.  It seems like the sensor may actually be seeing the same data but the Strobe count determines what data is displayed.  Does this sound reasonable to you considering you have the most experience with the instrument?

Kristen H.

[phy_mechanic]

Dear Kristen H.,

The vertical axis representing voltage, the horizontal axis is bin and obviously it is determine by time.

In my experiment, I am using an artificial signal (sine wave) as an input, so there no reason that bins 1026 or above is much larger than bins 1025 or below.

Actually, I am using the same data with different strobe number. And the strobe is used for selecting what data is displayed. But I don’t know why the data at 1026 or above is so different.

phy_mechanic

[Kristen_K.]

Hi phy_mechanic,

Can you verify that the artificial signal is more than two cycles?  What is generating the signa?

Kristen H.

[phy_mechanic]

Dear Kristen H.

Can you verify that the artificial signal is more than two cycles?

I have double check it by a CRO, the artificial signal is continuous.Also when I increase the frequency I can observe more than 2 cycles.

What is generating the signal?

I am using a signal generator to generate this signal.

The  generated signal is a sine wave with frequency 40kHz, amplitude 0.2V, offset 0.2V.

Does it help?

phy_mechanic