Suncal Overview

The sun may serve as an external radiation source for calibration of a radar system. This technique is simple and requires no external hardware to the radar system. The sun's position can be calculated from any point on Earth at any given time provided that accurate time and lat/lon information is known. This provides a convenient check for the antenna pointing accuracy. The sun's power can also be a useful technique for monitoring the calibration of the receive chain of the radar when used in conjunction with independent measurements of solar flux density. Solar flux densities are known to vary with frequency and are measured accurately over the 100 to 10000 MHz band from various solar observatories. Antenna beam width can also be computed from sector scans of the sun.

The Suncal utility performs sector scans of the sun's position and outputs calibration data. The utility is supplied with both the RDA and IRIS releases and works with the RVP signal processors and any antenna controller accessible through the antenna library. The Suncal utility can be run interactively from a command line and does not use a graphical interface. It can also be inserted into the Task Scheduler as an Exec Task and run on a routine basis.

The Suncal utility outputs a BEAM product. The BEAM product contains SNR data with no thresholding and can be viewed on an IRIS system, but is not automatically inserted into an IRIS product directory. The BEAM product is then processed to produce a final calibration results file.

On dual-polarization radars, Suncal can output a second BEAM product containing LDRH data. This is used to compute the LDR offset.