Hi,
i'm trying to measure pulsed Voltage ( current thru a shunt R).
I'm a bit confused how the DMM 34465A is measuring pulse.
here is my SCPI sequence:
TRIGger:SOURce EXT
TRIGger:SLOPe POS
TRIGger:DELay 10 us
VOLTage:APERture 1 ms
but how do i specify the integration time for which the Voltage will be measured in the pulse ? i 'm not sure to get it.
thanks for your help,
Michael
i'm trying to measure pulsed Voltage ( current thru a shunt R).
I'm a bit confused how the DMM 34465A is measuring pulse.
here is my SCPI sequence:
TRIGger:SOURce EXT
TRIGger:SLOPe POS
TRIGger:DELay 10 us
VOLTage:APERture 1 ms
but how do i specify the integration time for which the Voltage will be measured in the pulse ? i 'm not sure to get it.
thanks for your help,
Michael
the command "VOLTage:APERture 1 ms" explicitly sets the integration time, to 1 msec in this case. NPLC is not necessary, as it's an alternative command to APERTURE.
The data rate is determined by your external trigger, I assume it's synchronous to your current pulse? Do you use the rear trigger input jack?
The max. trigger rate would be the inverse of (1ms + 10us)
You will capture the pulse, if it's correlated properly to this external trigger.
It would be easier to use internal, level triggering, to capture the pulse, but this requires the DIG option.
Are you aware, that the 34465A is able to do this measurement directly on its DCI mode, w/o external shunt.
Frank
thanks for your quick reply.
to answer your last question, we are characterizing High power PA ( few hundreds watts) so we prefer to use external shunt in case we need to change it.
We use rear trigger jack connected to RF SigGen output trigger. We have the DIG option to run short trigger delay ~20us.
I'm used to measure Voltage/ Current in pulse with scope, setting trigger delay and windows width so i could measure exactly where i want in teh pulse...i thought aperture was to average pulse over time, so a bit confusing
so if the pulse is 250us/10%, trigger delay = 10us...and if i want to measure in 50us windows after trigger delay...what config should i use ?
thanks for your help,
rgds,
Michael
I tried to understand your setup, as some details are missing. Therefore I may give you some general statements as an answer only.
If you are accustomed to scopes, then you might use the 34465a in the same manner, by using TRIG:SOURce INT and TRIG:LEV xxx.
Then the 34465A will start to acquire at the set level xxx, instead of using the external trigger signal.
I still do not know, what the relationship between your current pulse and your external trigger signal would be.
Also I only can guess, that the current pulse is about 250µs long, but has a duty cycle of 10%, (i.e. 25µs on, 225µs off??), so that you should use a higher resolution and really digitize the pulse, instead of just trying to average over 1ms. You might use the full timely resolution of APERture = 20µs, and acquire at least 50 samples, (SAMP:COUNt 50) i.e. over 1ms.
Again, APERTURE defines the sampling time of the A/D. The input signal path does no averaging, as it has about 300kHz bandwidth for DCV.
The A/D itself is a multislope type, so it will average the input signal, but the characteristics of this averaging is not defined quantitatively.
The signal must strictly be inside the range limit, like +/- 1.2 V or +/- 12V. Any pulse above that range limit will not be averaged, but will give an overflow error.
I hope, that I caught your problems correctly.
Frank