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4. Functions
Impedance
The impedance generally expresses the resistance of alternating current signal and is merely called
resistance for direct current signal.
The resistance of the signal input circuit (digitizer board) is called an input impedance.
The input impedance can be set to 50Ω or 1MΩ for CONTEC digitizer board.
The current flows to the digitizer when the input impedance of the digitizer is low, and the measurement
result is influenced by the voltage descent.
Therefore, set the input impedance of the digitizer as high as possible, and reduce the measurement error
by connecting the digitizer as much as possible.
For example, set the input impedance of the digitizer to 1MΩ to measure signals of the circuit etc.
However, the resistance of 50Ω maybe necessary for the terminal resistance depending on the
instrument of the measurement object.
In this case, the correct voltage can be measured by setting the input impedance on the digitizer side to
50Ω.
Coupling
The coupling is a method of connecting the circuit of the measurement object with the digitizer to
transfer signals.
The input coupling can be connected to DC, AC or the ground.
DC coupling
All the input signals can be displayed.
AC coupling
The acquired signal are displayed at the center of 0V by intercepting the DC element from the signals.
Ground coupling
The input signals are intercepted from the vertical axis circuit, and are short-circuited with the ground in
the digitizer.
The acquired signal becomes DC voltage of 0V.
Band width
Band width can also refer to frequency bandwidth, and is defined as the 3db attenuation point of the
amplitude of sinewave input signal.
3dB is known as the input signal attenuated by 70.7% of its original amplitude.
The band width of this product becomes 60MHz.
Moreover, this digitizer board carries a 20MHz band width filter, so that it can suppress the effects of a
high frequency noise.
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DIG-100M1002-PCI
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