User's Manual

FOD Finder Radar Calibration and Verification (cont.)
The radar calibration is a function of the relative electrical line lengths of traces
within the radar and the impedance of the radar MMW circuits. If no physical
changes are made to the radar, these values do not change appreciably. There
may be small changes in the system parameters over time due to changes in
temperature or aging of components. Automatic updates to the calibration files,
based on the returns of known objects in the field-of-view (such as runway
landing lights), are incorporated to correct for these small changes over time.
Calibration of the radar is verified by monitoring returns from fixed objects
within the radar field-of-view and comparing the current phase and amplitude of
returns to those measured when the radar was first installed. This requires no
user action, assuming said data is exportable to Trex Aviation for analysis. As
part of a standard system performance verification, current radar returns and
calibration data are exported to Trex Aviation and the validity of the updated
calibration file is confirmed. A visual image of a runway with side marking lights
and a runway centerline light is shown on the next page. While this is a visually
reconstructed image, the data used are those needed to verify the system
calibration. Phase and amplitude returns from selected point targets, such as the
landing lights (which appear as white dots in the image), are used for calibration
verification.
15