[time-nuts] Stanford Research SR620 Measurement Bias

Magnus Danielson magnus at rubidium.dyndns.org
Thu Oct 1 16:37:03 UTC 2009


Stan,

Stan wrote:
> Thanks for the tip! Your method eliminates the interaction between the
> effects of the CalByte 50 and CalByte 4 adjustments in a way that makes
> perfect sense. After some trial and error, I found that it's easier to get
> the CalByte 50 adjustment right using the short (0.01 s) timebase setting
> rather than the long (1 s). My SR620 is now a whole lot more accurate and
> the bias is essentially gone.

Wonderfull!

> My one complaint is that I can't see the actual counter readings while I'm
> adjusting the CalByte values. I haven't looked into this yet, but are the
> readings being outputted from the scope or printer outputs on the rear panel
> during the cal adjustments?

Use the serial port. You can adjust the calibration values using the 
BYTE and WORD commands. See page 40.

read word 50:
WORD?50
write word 50 to 1234:
WORD50,1234

That way you can keep the reading on the display while using a terminal 
emulator to adjust it.

It should not be too hard to make a little program to automize this 
calibration.

Cheers,
Magnus



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