User Manual

5
Chapter 3 Operation
Zeroing Sensor
Over time, the sensor’s “zero value” (reading with no
applied RF power) can drift, making all readings inac
-
curate by this value. For example, if the zero value is –
0.02
W, measuring a 50 W signal will give a reading of
49.98
W, a 0.04% error. Measuring a 1 W signal will
give a reading of 0.98
W, a 2% error. If the drift would
be a significant error, rezero the sensor:
1. Ensure the sensor has reached a stable operating
temperature.
2. Ensure no RF power is applied to the sensor.
3. Press “Zero” to begin Calibration.
 Note: Calibration will take about 40 sec-
onds. Do not interrupt the calibration! A bar on
the screen will display calibration progress.
Power Measurement Accuracy
Accuracy
The Bird power sensors are highly accurate. Accuracy is
specified for each sensor type is typically given as a per
-
cent of reading or of full-scale.