Kannad Marine Rescuer 2 SART User Manual

Page 6

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The timescale over which all this occurs is very short. Each "fast" sweep takes about


s, each "slow" sweep about 7.5


s. The complete series of twelve forward and

return sweeps is therefore complete within 100


s. Displayed on the PPI; the spacing

between each pair of dots will be 0.6 nautical miles.

On a long range setting, a typical radar will be triggering the SART every millisecond -
but only during the period that the rotating radar scanner is pointing in the correct
direction. Most modern radars use sophisticated noise rejection techniques, which
prevent the display of echoes which are not synchronized with the radar's own
transmissions, so one radar will not normally be confused by a SART's response to a
neighbouring radar.

The SART indicates that it has been triggered by lighting an indicator LED
continuously (it flashes in standby mode) and by sounding an integral buzzer. If no
radar pulses are detected for a period exceeding 15 seconds, the SART reverts to
"standby" mode.