Hardware description of the dataman 770 family – Dataman 520 Series User Manual
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DATAMAN oscilloscope
User’s Guide
memory. This structure of data acquisition creates the illusion of the onboard
memory having a capacity determined by the length of ACC counter.
2.3. Hardware description of the DATAMAN 770 family
The DATAMAN 770 series of dual channel digital storage USB oscilloscopes
connect to the computer via USB. They are compatible with both USB 2.0 and USB
1.1. Measurement accuracy is achieved by the stability of the parts used together with
the computing power of the computer. Calibration data are part of the HW, which
makes it impossible to loose them (oppose to the calibration data located on the
diskette). Therefore, it is possible to simple connect the hardware to any computer
(via USB 1.1 or USB 2.0 interface). All you have to do is just installing the software.
The common potential of measuring inputs (measuring ground) is isolated from the
common potential (ground or chassis) of the host computer.
The DATAMAN 770 series oscilloscopes allows user to measure waveforms using
two independent channels with resolution of 8 bits and sensitivity from 10mV/div to
5V/div (80mVfs to 40Vfs) in 9 steps. One division of the oscilloscope screen contains
32 dots. Input impedance matches the oscilloscope standards therefore any regular
oscilloscope probe (with minimum compensation range of 32pF) can be connected to
the device. The software supports 1:1, 1:10, 1:100 and 1:1000 probes. AC or DC
coupling and type of probe can be independently selected for each vertical channel.
Any of the inputs can be grounded without disconnecting the probes from the
measured system. Vertical track position can be controlled with accuracy of 1 pixel of
the oscilloscope screen. Measurement can be triggered from the Channel A, Channel
B and/or External trigger input. Trigger threshold can be set independently for each
channel in the range of whole oscilloscope screen with resolution of one pixel.
Threshold of the External trigger input is fixed to about 1.5V (TTL and CMOS
compatible). The DATAMAN 770 series oscilloscopes have the dual level triggering
system, which is closely described in chapter 2.1.2. Oscilloscope hardware offers data
acquisition with maximum rate of 50, 100 or 200MS/s depending on the model.
Therefore it is not possible to sample non-repetitive waveforms faster than every 20,
10 or 5ns (depending on the model). However, thanks to random sampling method, it
is possible to sample repetitive waveforms with period of 200, 100 or 50ps
(depending on the model), which corresponds with equivalent sampling rate of 5, 10
or 20GS/s. For displaying waveforms acquired using the random sampling method,
we use system called WCD (Waveform Conformity Detection), which speeds up
display of changes of measured waveform.
The oscilloscope hardware can acquire data in one universal mode.
Acquiring data before and after trigger with selectable trigger position displays
waveform before and/or after trigger. The position of the trigger is selectable by the
user. In this mode the hardware of the oscilloscope starts data acquisition immediately
after the start of measurement. The trigger event terminates the data acquisition after
collection the data amount set by the user. The trigger position can be set to any place
between these margins. The “Hold Off” timer allows the user to prevent the
occurrence of a trigger event after the start of data acquisition. This feature allows to
acquire proper amount of data before the trigger.
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