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Input Device Settings

The Input Device is used by the analyzer when Recording or running in the Real Time mode.  

Click the <Options><Processing Settings> menu (or press F4) and select the "Input" tab to access the input device settings.  You can also click the I/O toolbar button to access these settings.

All DT-9800 hardware modules that are currently connected to your computer are shown in the device list.  The analyzer will communicate with the selected device and determine which settings are adjustable.  Not all DT-9800 devices support all settings; some of the device settings will be disabled or have only one possible selection.  Consult your hardware documentation for details.

Enable: controls which input channels are enabled for Real Time analysis or Recording.

Input Range: selects the input voltage range (gain) used by the device.  This value is in volts (peak).  A signal exceeding this level will overload (clip) the input.  Overloaded channels are shown in red on the lower status bar.  Not all DT-9800 devices support adjustable input gain.

Input Coupling: selects whether the input channel is AC or DC coupled.  AC coupling is typically used for most audio and vibration applications.  Not all DT-9800 devices support this feature.

IEPE Current: controls whether or not IEPE (constant current) power is turned on.  IEPE is used by many transducers (microphones and accelerometers) and eleminates the need for external power supplies.  This reduces cost and simplifies wiring.  Not all DT-9800 devices support IEPE power.

Low Pass Filter: controls whether or not a low pass filter is applied prior to the digitizer.  Not all DT-9800 devices support this feature.

Sampling Rate:  Selects the sampling rate to use for all enabled channels.  The same sampling rate applies for all channels.  

The DT-9800 family of devices fall into two categories 1) Sequential Sampling and 2) Simultaneous Sampling.  

Sequential sampling - one digitizer is used for all channels.  Each channel is sampled at a slightly different instant of time as the digitizer cycles through all enabled channels.  In addition, the maximum sampling rate per channel is equal to the maximum device sampling rate divided by the number of enabled channels.  For example, if the maximum hardware rate is 500 kHz and 10 channels are enabled, each channel can sample at a maximum of 50 kHz.  If two channels are enabled then the maximum per channel rate is 250 kHz.  The "Aggregate Rate" is the per channel rate multiplied by the number of enabled channels.

Simultaneous sampling - a separate digitizer is used for each channel.  All channels are sampled at the same instant of time.  Each channel can be sampled at the maximum device sampling rate.

Sampling Resolution:  This specifies the number of discrete levels that are used in the analog to digital (A/D) conversion process and directly affects the dynamic range of the measurement.  The list will only contain the sampling resolutions supported by the selected DT-9800 device.

Analog Input Type: selects whether the input channels are "Single Ended" or "Differential".  Not all DT-9800 devices support differential inputs.

Single Ended - input channels have a common signal ground.  

Differential input channels - input channels have isolated signal ground.  This provides maximum immunity from common mode voltage (ground noise).  When differential input type is selected the total number of available input channels is reduced by 1/2.  Consult your hardware documentation for wiring details.

See Also: Tachometer Channel