How often should I run SPC?

I was trying to find in a manual how often SPC should be ran on really all of your scopes. DPO, MSO, and the older TDS models. From what I saw it stated a shift of 5°C or before a critical measurement was taken. On screen the DPO5104 states the 5°C and within 30 days but I was curious if this was documented in a manual somewhere and if it differs between oscilloscope models. I've looked through multiple manuals and didn't see a length of time anywhere.

Hi Patrick,

As as general rule of thumb, SPC should be run in the following instances:

1. Power cycled: Every time you power up the scope, after waiting the 20 minute warm up period for the scope to arrive at a steady operating temp, SPC should be run.

2. Temp change > 5 degrees C: As you saw in the manuals, an external temperature shift will lead to a slightly different internal operating temperature for the scope, and should be compensated for.

3. Every 30 days: Normally one of the previous two conditions will have been met prior to this 30 day period coming into effect, but if not then you should run SPC once a month.

The 'before critical measurement' piece is more of a safeguard for procedural testing. It can give piece of mind that the signal path will be properly compensated without needing knowledge of the instruments operating history.