2 output signals, Output signals – Campbell Scientific CSAT3 3-D Sonic Anemometer User Manual
Page 12
CSAT3 Three Dimensional Sonic Anemometer
CSAT3 can be configured to make a single measurement per trigger or
multiple measurements that are centered around the trigger (oversampled).
OUTPUTS: u
x
, u
y
, u
z
, and c (u
x
, u
y
, u
z
, are orthogonal wind components
referenced to the anemometer head; c is the speed of sound)
SPEED OF SOUND: determined from 3 acoustic paths; corrected for
crosswind effects
MEASUREMENT RATE: programmable from 1 to 60 Hz, instantaneous
measurements; two oversampled modes are block averaged to either 20 Hz or
10 Hz
MEASUREMENT RESOLUTION: u
x
and u
y
are 1 mm s
–1
rms; u
z
is
0.5 mm s
–1
rms; c is 15 mm s
–1
(0.025 °C) with embedded code version 4
(standard) [c is 1 mm s
–1
(0.002 °C) with embedded code version 3]; wind
direction is 0.06 degrees rms. Values are the standard deviations of
instantaneous measurements made of a constant signal. The noise is unaffected
by the sample rate.
OPERATING TEMPERATURE RANGE: –30 to 50 °C (standard); –40 to
40 °C (cold shifted)
ACCURACY (–30 to 50 °C and –40 to 40 °C operating range; wind speed
< 30 m s
–1
; azimuth angles between ±170°):
Offset Error:
u
x
, u
y
:
< ±8 cm s
–1
u
z
:
< ±4 cm s
–1
Gain Error:
Wind vector within ±5° of horizontal < ±2 percent of reading
Wind vector within ±10° of horizontal < ±3 percent of reading
Wind vector within ±20° of horizontal < ±6 percent of reading
Wind Direction Accuracy:
±0.7° at 1 m s
–1
for horizontal wind
2.2 Output Signals
The CSAT3 can output data to a data retrieval system using any of the
following communications: SDM (Synchronous Device for Measurement),
RS-232, or analog output. All the output signals have a two scan delay.
DIGITAL SDM: A Campbell Scientific, Inc. 33300 bps serial interface for
datalogger/sensor communication
Data type: 2-byte integer per output plus 2-byte diagnostic and 2-byte
configuration parameter
DIGITAL RS-232: Baud rate: 9600 bps or 19200 bps
Data type: 2-byte integer per output plus 2-byte diagnostic
ANALOG: Number of outputs: 4
Voltage range: ±5 V
Number of bits: 12
2