User`s manual

1-14
IM 701610-01E
1.4 Setting the Acquisition and Display Conditions
Record Length <Section 7.1>
The term “record length” refers to the number of data points (per channel) acquired in the
acquisition memory. “Displayed record length” refers to the number of these data points
that are actually displayed on the screen. (Note that sampling rate and record length will
vary according to the time axis setting; see section 1.2.) It is possible to set the following
record lengths. (The maximum record length that can be set varies depending on the
status of the high-resolution mode.)
DL1620/ : 1 kword, 10 kwords, 100 kwords, 1 Mword, 8 Mwords (in high-resolution
DL1640 mode 4 Mwords).
DL1640L : 1 kword, 10 kwords, 100 kwords, 1 Mword, 4 Mwords, 10 Mwords,
32 Mwords (in high-resolution mode 16 Mwords).
The displayed record length is identical to the (acquisition) record length. For details,
see Appendix 1.
High-resolution mode <Section 7.4>
Ordinarily, data converted to digital values by the 8-bit A/D converter is processed
according to the settings and saved by the device as 8-bit data in the acquisition
memory.
For filtering that uses the FIR filter or IIR filter digital calculation methods, data is
processed at 8 bits or higher to minimize calculation errors. Further, limiting the
bandwidth improves the S/N ratio and enables data exceeding 8 bits in length. Using the
DL164/DL1640L, the S/N ratio can be improved to allow data of up to about 13 bits.
When the high-resolution mode is ON, calculated data is saved in acquisition memory as
16-bit data. Therefore, data obtained through filtering that exceeds 8 bits can also be
saved. However, when the bandwidth limitation is set to Full, the resolution does not
improve even if the high-resolution mode is ON because there is no filtering.
When the high-resolution mode is ON, the following restrictions apply. These restrictions
do not apply when high-resolution mode is OFF.
• The maximum sampling rate of the real-time sampling mode is halved (100 MS/s)
• The maximum recording length is halved (DL1620/DL1640: 4 Mwords/CH; DL1640L:
16 Mwords/CH)
• The number of triggers that can be held in history memory is halved
When the high-resolution mode is OFF, all data is saved as 8-bit data, regardless of
bandwidth limit settings.