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IM 701310-01E
Explanation of Functions
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Index
High Resolution Mode ►For the procedure, see section 7.2
Normally, this unit takes digital values from the 8-bit A/D converter, applies specified
processing, and then stores 8-bit values in primary memory.
On the other hand, the resolution of the A/D converter can be improved equivalently by
placing a bandwidth limit on the input signal.
In high resolution mode, the effective number of bits per data value in the primary
memory is expanded to 12 bits, and data is stored by maintaining the improved resolution
through bandwidth limiting.
Record Length ►For the procedure, see section 7.3
The term record length refers to the number of data points acquired per channel in the
acquisition memory. The record lengths that can be set are: 2.5 k words (2500 points),
6.25 k words, 12.5 k words, 25 k words, 62.5 k words, 125 k words, 250 k words, 625 k
words, 1.25 M words, 2.5 M words, and 6.25 M words (the maximum record length that
can be set varies from model to model). Basically, if you change the time axis setting, the
sample rate is changed to maintain the set record length at the same value. However,
in some cases the record length is changed as a result, for example, of a changed time
axis setting (see Appendix 1).
Sampling Mode ►For the procedure, see sections 7.4 to 7.6
Depending on the time axis setting, you can switch the mode for sampling the input
signal (sampling mode). The time axis ranges that allow the sampling mode to be
changed vary depending on the acquisition mode and other settings. For details, see
Appendix 1.
Realtime sampling mode
Changing the time axis setting causes the sample rate to change. Data can be sampled
at up to 5 GS/s (2.5 GS/s when interleave mode is OFF). The input signal is sampled
sequentially, and the data is stored in the acquisition memory.
In this mode, according to the sampling theorem*, the signal can only be correctly
displayed up to a frequency which is one-half of the sample rate (samples per second, or
S/s). Therefore, an appropriate sample rate for a signal is such that the frequency of the
signal is comparatively lower.
* If the sample rate is relatively low compared with the input signal frequency, then higher
harmonic content of the signal will be lost. In this case, according to the Nyquist sampling
theorem, the high frequency components may be transformed into low frequencies, by the
process known as aliasing. By setting the mode to envelope signal acquisition, aliasing can
be avoided.
Aliased signal
Input signal
Sampling point
2.5 Acquisition Conditions
