Model DMM7510 7½ Digit Graphical Sampling Multimeter Reference Manual
Section 2: General operation
DMM7510-901-01 Rev. B / May 2015
2-131
Digitizing aperture and sample rate
In most cases, you will get good results if you leave the aperture at the default setting of automatic.
When auto is selected, the instrument makes as many measurements as possible in the sample
period. When it is set automatically, it is set to 1 mega sample/second (rounded down to the nearest
integer).
You might want to set a manual aperture if you need an aperture that contains a higher than one
discrete 1
µ
s averaged reading.
Although the maximum sample rate is 1 million samples per second, the input filtering of the A/D is
set at a 3 dB corner point of slightly greater than 350 kHz to prevent aliasing. Therefore, a 350 kHz or
higher voltage input is attenuated by a factor of 0.707. For dynamic signals, this attenuation could
cause attenuated readings. Consult the specifications for detail.
Input frequencies above 500 kHz are occasionally prone to the signal processing problem of aliasing.
The following figure shows the relationship between the aperture, sample rate, and count.
Figure 97: Digitize aperture, sample rate, and count
For large count (more than 8,000,000) and sample rate values (more than 150,000), data may lost.
Adjust one of the values to a lower level.
