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4. Functions
Horizontal Axis Setting
The horizontal axis setting becomes the common setting contents for plural channels.
Reference clock
CONTEC digitizer uses LVTTL signal of 10MHz, duty ratio of 50% as a reference clock.
The reference clock of 10MHz is a frequency that can be used by most measuring instruments.
This reference clock is used as an input to PLL ( Phase-locked loop).
This clock is made 10 times in PLL, and the signal of 100MHz is generated to the AD converter for
clock use.
The source signal of the reference clock can be selected from the digitizer itself or an external signal.
When only the digitizer board is used, the crystal transmitter in the board is used as the reference clock
source to PLL.
To perform the synchronization between plural digitizer boards, with synchronization bus, output the
reference clock on master device side, and input the reference clock on slave device side.
Moreover, BNC connector (CLK) for reference clock I/O is used to perform the synchronization of the
reference clock between external instrument and the digitizer.
Sampling clock
The sampling clock is a clock signal that generates the timing to acquire AD conversion data.
The AD converter always performs sampling at 100MHz for that it uses the reference clock output from
PLL.
The digitizer transfers the conversion data to the memory after extracting it at the period of the set
sampling clock.
To perform the synchronization between other CONTEC device, with synchronization bus, output the
sampling clock on master device side, and input the sampling clock on slave device side.
Moreover, BNC connector (TRG) for trigger I/O is used to perform the synchronization of the sampling
clock between external instrument and the digitizer.
Sampling rate
It is possible to set the sample rate when the sampling clock of the digitizer itselt is used.
The sample rate is expressed as a frequency (sample times per second), and the unit is Hz.
The sample rate can be set within the range from 0.025Hz to 100,000,000Hz.
By the nyquist theorem, a signal must be sampled at a frequency at least twice the maximum frequency
element.
When the sample rate is less than that, the phenomenon called aliasing occurs that an original signal
cannot reproduce.
Record
One waveform data is expressed by a record unit.
The record data consist of pre-trigger sample data and post-trigger sample data.
record = pre-trigger sample + post-trigger sample
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DIG-100M1002-PCI
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