Products > Test Equipment
Pocket-Sized 6 GHz 1 TS/s ET Scope
joeqsmith:
I ran a few tests to try and help answer what is going on with noise.
For starts, rotate the original date where we are looking at the sweep time rather than the number of sweeps. Again, subtracting off the mean as previously described. Note how channels 2,3&4 show the disturbance around 11.75ns.
joeqsmith:
As I mentioned, I repeated the test doubling the input voltage and using the rising edge trigger. Showing about 2.5 hours of data. The p-p noise is greatly improved.
joeqsmith:
To try and narrow down why we are seeing this improvement, the input signal was returned to the same level that was used during the original test but the trigger remained set to the rising edge. Here we are looking at about 5 hours of data.
joeqsmith:
So, is it the trigger edge? Time to repeat the original test using the same signal levels and falling edge. I let it run about a half hour longer than the original test.
joeqsmith:
I'm at a loss of what to suggest. Same cables, generator, scope, splitter, PC, USB port, software... Scope and splitter resting on a ground plane next to my VNA. The setup wasn't taken apart between tests. I wasn't playing with my spark gap transmitter, ignition systems or anything else I would expect would cause a disturbance.
The only thing that has really changed is or course, its a different day and the office temperature was lower. As you know, I had tried to look at the stability with temperature but at that time we did not have the new FPGA/firmware. I plan to repeat these tests once your software has evolved. Maybe that has something to do with it.
Let me know if you have any ideas.
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If the setup is not clear, see attached sketch.
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