Tektronix DPO3034 Calibration and Signal Path Compensation

[alper.y]

Hi,

We have couple of DPO3034s lying around in our lab. Scopes are sent to a third party calibration facility regularly. What I have noticed is that there are some scopes that have never performed a SPC (signal path compensation) after leaving the manufacturing factory like since 2011 (nobody really cares SPC  ) But that scope was calibrated in 2013 and 2015, for example.

Is it possible to calibrate scopes without making SPC? I don't know the calibration procedure and couldn't find steps easily. Is facility cheating on us?

Thanks.

[nctnico]

Well if the SPC hasn't drifted outside the specs then there is no need to run it.   
According to the Websters English dictionary calibration means checking AND adjusting but in test house slang it means checking only.

[alper.y]

Well, what I think is that they hook up a test signal to scope channels to see whether it is within specs or not. You don't know status of SPC + calibration, two unknowns are there. How can you sure that both of them (SPC and calibration) are fine? SPC isn't the only error involed in measurement. You don't know the status of calibration too. How can you measure the effect of SPC only? What am I missing here?