Iwatsu DS-8814, Operation Manual

Page: 69 / 141

50
ACQUISITION
Detects the Max. and Min. values that occur in a period twice longer
than the sampling period corresponding to the sweep time (see
appendixes 1 and 2) and alternately records the detected values in
memory. The minimum time allowing detection of the Max. and Min.
values is 5 ns (200M sample/s).
If the sweep time is set to 10
µ
s/div (10 M samples/s) with short memory,
it is not possible to capture the waveform peak A in the figure below
which occurred in the sampling interval without peak detection.
Peak detection always captures waveforms in 5 ns period (200 M
samples/s) irrespective of the set sampling period and alternately records
Max./Min. as data, making it possible to capture phenomena that occur
in the sampling period correctly.
Pulse signal
Example of measurement of 10 ns pulse signal with repetition frequency
of approx. 11 kHz
Peak detection mode is OFF In peak detection mode
Since the pulse width (10 ns) of the signal is 1/10
of the sampling period (100 ns), the pulse signal
cannot be captured completely. Since sampling is always performed in 5
ns period, pulses in the sampling period
(100 ns) are captured correctly.
Peak
detection
(Peak Det)
Input signal
Captured data
Without peak
detection
With peak
detection
Captures data in
sampling period.
Always captures
data in 5 ns period.
Expresses data with dots
in sampling period.
Expresses data with lines
in sampling period of
Max. and Min.
Note 1
Note 1
Note 1: Screen display when Join in Display menu is set to Off
Sampling period according to sweep time = 10 M samples/s
Appendeces 1, 2)