AR3000 User’s Manual
27
Rev 1/10
7.
Performance and Optimization
7.1.
Measurement Modes
The AR3000 will not begin measuring and reporting until the user selects a measurement mode.
Once initiated, the distance will be measured, and when a sample result is computed, it will be
sent on both the serial, analog, and alarm signals. See section 5.2 to specify the serial format,
section 5.6 to specify the analog behavior, and section 6 to specify the alarm behavior.
The sample result values are affected by the scale factor and distance offset values (SF and OF -
See section 7.2).
Users may select among several measurement modes that will optimize the sensor’s speed or
accuracy performances for the specific measuring application.
The overall data output speed will depend on the ratio between the sensor’s measurement
frequency (MF) and the averaging function (SA).
7.1.1.
Perform Distance Measurement (DM)
This command causes the AR3000 to performs one set of measurements and generates the
output(analog, alarm, and serial) based on the resulting average.
Type
DM<Enter>
to initiate a single distance measurement. This command does not change
any configuration settings.
The time required for each measurement depends on the number of averaged samples (SA)
and the preset measuring frequency (MF). With the factory default settings the DM command
takes 10 ms to complete.
The time for the output depends on the measurement frequency.
7.1.2.
Start Distance Tracking Mode (DT) (<Esc> to stop)
In the Distance Tracking mode, the AR3000 performs continuous distance measurements
(like repeating the DM command) until stopped with the Escape character (0x1B) via the
serial port (<Esc> key in HyperTerminal).
Type
DT<Enter>
to start the distance tracking mode. This command does not change any
configuration settings.
Type
<Esc>
to stop tracking the distance. Note: This is the only way to stop.
The output rate of measured values depends on the number of averaged samples (SA) and the
preset measuring frequency (MF). With the factory default settings, DT mode will generate
sample results at 100Hz.
7.1.3.
Perform Velocity Measurement (VM)
This command causes the AR3000 to takes 25 averaged samples, after which it will use those
25 samples to calculate a resulting velocity. The alarm and analog outputs are updated for
each sample (at the DT mode rate), but only one serial output is generated after the 25
samples are complete. The maximum measurable velocity is 100 m/s. With the factory
default scaling factor (SF1) the velocity units will be m/s.
