I'm using the channels on the PicoScope 5444D to collect samples of an incoming signal. I'm using 8bit block mode. The goal is to collect 100 samples/cycle of the incoming signal and to collect 100 total cycles of the incoming signal.
If I have 100 total cycles with 100 samples/cycle my numPostTriggerSamples should be equal to 100*100 = 10,000. This is what I set it to.
100 samples/cycle means the sample frequency needs to be 100 times faster than the incoming signal (2500 Hz). Thus the sample interval is 1/(100*2500Hz) = 4000 ns
According to the picoscope 5000 series a api programmers guide (pg. 22), for 8bit resolution and a sampling interval greater than 8 ns, the equation for the timebase index is: (n2)/(125,000,000)
4000 ns = (n2)/125,000,000 > n = 502 = timebase index
When I run the script I only receive approximately 40 total cycles. Not the 100 I expected. Through trial and error I discovered that setting my timebase index to 1255 gives me almost exactly 100 total cycles. Also, if I increase the frequency of the incoming signal, continue to use 8bit resolution, and use the equation above my total number of cycles becomes progressively lower and lower.
The ultimate goal is to obtain 100 cycles/freq and 100 total cycles of several different incoming frequencies. I can't seem to figure out what is going wrong. I have attached a matlab test script as a text file for reference.
Capturing Correct Number of Cycles with PicoScope 5444D
Capturing Correct Number of Cycles with PicoScope 5444D
n = 502 = timebase indexWhen I run the script I only receive approximately 40 total cycles. Not the 100 I expected. Through trial and error I discovered that setting my timebase index to 1255 gives me almost exactly 100 total cycles. Also, if I increase the frequency of the incoming signal, continue to use 8bit resolution, and use the equation above my total number of cycles becomes progressively lower and lower.
The ultimate goal is to obtain 100 cycles/freq and 100 total cycles of several different incoming frequencies. I can't seem to figure out what is going wrong. I have attached a matlab test script as a text file for reference.
 Attachments

 Test_Script.txt
 (3.92 KiB) Downloaded 211 times