Fluke PM6681R, PM6685R manual measure, ments/second, Block Measurements, Real Time Calculation

		How to Measure Fast
interpolators by using	the	40000 measure-
CAL:INT:AUTO ONCE command.
		ments/second

Block Measurements

When dumping measurement results into the internal memory, it is important to program the arming and triggering coun- ters in the best way. For maximum mea- surement rate use the block armed mode.

To do this set: :ARM:STARt:LAYer:COUNt￿1

and

TRIG:COUNt￿ <N>

where <N> is the number of measure- ments in a block.

Real Time Calculation

Normally the counter calculates the re- sults in “real time.” This means that for each measurement, the counter immedi- ately calculates the result based on the raw data information in various counting registers. It needs to do this in order to display the result, make mathematical calculations, limit testing and statistical calculations. It is possible to defer the calculations until the controller requests these values. The counter intermediately stores the measurement data in a packed format. This is done with the command:

:SENSe:INTernal:FORMat￿ PACKed.

￿This is the most important com- mand when you want to improve the measurement rate for block synchronized measurements.

Note: If you want a very high speed you must set :AVER:STATE￿OFF and

:ACQ:APER￿ MIN.

(Only PM6681)

PM6681 can make measure every period of a signal with up to 40 000 Hz. This is called “Back-to-Back” period measure- ments and in only available via GPIB. The high speed is obtained when the PM6681 measures low-resolution mea- surements directly to its internal memory. That memory can store 6143 measure- ment results. When full, the measurement must be stopped, and the results fetched by the controller. )

Note also that some functions are dis- abled to obtain high measurement speed: You cannot use external arm/trig or hold-off. Statistics is also disabled.

Example: 1000 back-to-back periods

:SENS:FUNC￿"PER￿1"

Select period as measurement function

:INP:COUP￿DC Select DC coupling

:INP:LEV:AUTO￿OFF Turn off Auto Trigger

:INP:LEV￿1 Set fixed trigger level

:SENS:ACQ:RES￿LOW Select low resolu-

tion/high speed measurements

:SENS:INT:FORM￿PACK Suspends the re- sult calculation until the capture is ready

:TRIG:COUN￿1000;:ARM:COUN￿1 Set up PM6681 for 1000 measurements

:INIT Start a capture

:FETC:ARR?￿1000 Fetch the 1000 results from the internal PM6681 memory

40000 measure- ments/second 7-9