Parametric Analysis

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4 Dec 2008
Posts: 1

I am wondering if we can use 2 cleverscopes to create a parametric analysis system.

The idea is to fix the output voltage of the 1st cleverscope’s source and sweep the second cleverscope’s source. Then rechange the first one and redo the same sweep, etc.

If yes, could you please tell me how?
rhcarter rhcarter

5 Dec 2008
Posts: 114

You can use two cleverscopes, with two copies of the standard program (rename one of the cleverscope.exe to something else, eg cscope2.exe), or you can use the 4 channel version of the cleverscope software (cleverscope4.exe) to achieve the same thing.

This is how it would work:
I'll use an example - but you can substitute your own requirement. Say you were measuring the audio passband from 20 Hz to 20 KHz, while changing the bias voltage on a transistor. You wanted the transfer function. You need to know when the sig gen is set to 'Sweep Synchronous' it only sweeps when it sees a trigger.

1. Cleverscope 1 is setup to sweep synchronous, sweep up continuous, from 20 Hz to 20Khz, peak captured averaging, with the spectrum graph showing 20Hz - 20 kHz. The output of the sig gen goes to the transistor amp, and to Chan A. The output of the transistor amp goes to Chan B. The Spectrum transform type is Gain/Phase (Settings/Spectrum/Transform Type = Gain /Phase). We use Peak Averaging (Settings/Averaging/Weigting mode = Peak) to show the whole frequency response.
2. Cleverscope 2 is setup to sweep DC. Say the range we want is from -1 to +1 V. We set the waveform type to DC. The Base Frequency and Range now refer to the DC range - we set the base at -1. The Range is 2V. The step is 0.1 V say. The Sweep method is Sweep Synchronus. The Sweep Action is Sweep Up Once.
3. The output of the Cleverscope 1 sig gen is also wired to Cleverscope 2 Chan A (though it could be Chan B, Ext Trig, or a digital input). With a 20 kHz signal we expect a period of 50us, and a pulse time of 25 us. We set the Cleverscope 2 to trigger when the pulse width is less than 25us - that is when Cleverscope 1 has reached maximum frequency. (This is Trigger 2 settings/Trigger 1 inverted, threshold = 0V, Trigger 2 usage = Trig 1~2<min, min = 25u).
4. Finally Cleverscope 1/Digital Input 1 is connected to Cleverscope Sig Gen 2 output. We set the digital threshold to 1V. We set Cleverscope 1 to trigger on Chan A (the sig gen). We set the Digital Pattern to required. We set the digital pattern to xxxx xxx0. This means Cleverscope 1 will only trigger if Cleverscope 2 Sig gen 2 is less than +1V.

Ok here is how it works:

a. We start both scopes, and set the sig gen slider to minimum. We start sweep on both scopes. Cleverscope 1 starts sweeping from 20Hz - 20 Khz. Cleverscope 2 puts out the minimum Dc (-1V) - which could also be a frequency.
b. Once Cleverscope 1 reaches 20 KHz (pulse time of 25us), Cleverscope 2 triggers and steps up the DC by 0.1V.
c. If Cleverscope 1/Digital Input 1 is <1V, Cleverscope 1 starts another sweep.
d. The cycle b-c repeats until Digital Input 1 is >1V. The digital pattern is not met, and Cleverscope 1 stops sweeping. Because it no longer sweeps, Cleverscope 2 also stops sweeping.

In this way we achieve what you are after.

I hope you get the idea. Cleverscope 2 could also be stepping frequency, not DC.


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