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Section 8. Operation
446
8.1.3.8.1 Pay Attention to Specifications
Pay attention to specifications. Take time to understand the signal to be
measured and compatible input terminals and CRBasic instructions.
8.1.3.8.2 Input Filters and Signal Attenuation
U
and
C
terminals configured for pulse input have internal filters that reduce
electronic noise, which can cause false counts. However, input filters attenuate
(reduce) the amplitude (voltage) of the signal. Attenuation is a function of the
frequency of the signal. Higher-frequency signals are attenuated more. If a signal
is attenuated enough, it may not pass the detection thresholds required by the
pulse count circuitry.
The metric for filter effectiveness is τ, the filter time constant. The higher the τ
value, the less noise that gets through the filter. But, the higher the τ value, the
lower the signal frequency must be to pass the detection thresholds.
Detection thresholds, τ values, and low
-level ac pulse input ranges are listed in
Pulse Counting Function — Specifications
(p. 110)
.
For example, the amplitude reduction
that results from τ in high
-frequency pulse
input mode is illustrated in figure
FIGURE: Amplitude Reduction of Pulse Count
Waveform
(p. 446).
FIGURE 97: Amplitude reduction of pulse count waveform (before and
after 1 µs µs time-constant filter)
Содержание CR6 Series
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Страница 76: ...Section 5 Overview 76 FIGURE 20 Half Bridge Wiring Example Wind Vane Potentiometer ...
Страница 80: ...Section 5 Overview 80 FIGURE 23 Pulse Input Wiring Example Anemometer ...
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Страница 251: ...Section 7 Installation 251 FIGURE 46 Running Average Frequency Response FIGURE 47 Running Average Signal Attenuation ...
Страница 454: ...Section 8 Operation 454 FIGURE 104 Narrow Sweep High Noise ...
Страница 459: ...Section 8 Operation 459 FIGURE 106 Vibrating Wire Sensor Calibration Report ...
Страница 535: ...Section 8 Operation 535 8 11 2 Data Display FIGURE 121 CR1000KD Displaying Data ...
Страница 537: ...Section 8 Operation 537 FIGURE 123 CR1000KD Real Time Custom ...
Страница 538: ...Section 8 Operation 538 8 11 2 3 Final Storage Data FIGURE 124 CR1000KD Final Storage Data ...
Страница 539: ...Section 8 Operation 539 8 11 3 Run Stop Program FIGURE 125 CR1000KD Run Stop Program ...
Страница 541: ...Section 8 Operation 541 FIGURE 127 CR1000KD File Edit ...
Страница 542: ...Section 8 Operation 542 8 11 5 PCCard Memory Card Management FIGURE 128 CR1000KD PCCard Memory Card Management ...
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Страница 549: ...Section 9 Maintenance Details 549 FIGURE 133 Separate Back Shell from Module FIGURE 134 Disconnect Battery Connector ...
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Страница 610: ...Section 11 Glossary 610 FIGURE 137 Relationships of Accuracy Precision and Resolution ...
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