Re: 11801 NVRAM

Albert Otten

Hi Reg,

I think you refer to my message #158778. The GPIB command ccalcorrection does the job. That command was present in the CSA803A but not yet in the CSA803.This suggests that the calibration constants were introduced in the later models. So I suppose this feature is also not yet present in your 11801.

As far as I know there is no GPIB command to read memory contents. The Debug facility in the Extended Diagnostics menu can show memory contents at the scope screen; see also 11801 Diagnostics pdf, section 5.2.7. For viewing the time base NVRAM the Time Base subsystem should be selected in the E.D. menu. With Debug I could not find the GPIB commands in the firmware; probably some memory bank switching is needed to access the proper memory chips. I based my above mentioned conclusion on chip memory dumps obtained from elsewhere.


On Sun, Sep 15, 2019 at 07:59 PM, Reginald Beardsley wrote:

I'm very interested in how to derive and store the correction terms. There
has been discussion of a command to write them, but it appeared not to work
when attempted IIRC.

It would be very helpful to know where they are stored in the NVRAM. I've got
a programmer, but no idea where to put the data.

My Keysight 33622A is specified as <1 ps jitter. That's less than the 4 ps
jitter specified for the 11801. I think I'll play with that a bit and see if
I can persuade the 11801 to tell me what the uncalibrated errors are.

Having just built a GPIB-USB adapter using an Uno and AR488 I think I need to
read the programming manual for my 11801 to see if I can get digits out via
the GPIB port. That would allow removing the NVRAM one time to load the
correction values.

Have Fun!

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