MSP CTLR CONCERNED WITH CONSTANT ASDE (ARPT SFC DETECTION EQUIP) FALSE TARGETS WHICH ARE CONSISTENTLY IGNORED.

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THERE ARE ALWAYS FALSE TARGETS ON THE ASDE (ARPT SURFACE DETECTION EQUIP). WHEN THE WX IS GOOD; IT'S NOT A BOTHER BECAUSE WE CAN VISUALLY SCAN THE RWYS. WHEN THE WX IS BAD; WE CONSISTENTLY IGNORE THE FALSE TARGET. THERE'S NO WAY TO DISCERN IF IT'S A VEHICLE; ACFT; OR A LOST ACFT. WE DO NOT SEND ACFT ON FINAL AROUND AND ONE DAY; THIS COULD PROVE FATAL. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR ADVISED THAT FALSE TARGETS HAVE BEEN A NOTED PROB SINCE 1995 WITHOUT RESOLUTION. THE POORER THE WX; THE MORE THE FALSE ALERTS. RPTR STATED THAT CTLRS 'GENERALLY IGNORE' ALL ASDE ALARMS. THE CTLR IS AWARE OF A NMAC LAST YEAR BETWEEN AN ISSUED GAR AND AN IFR DEP DUE TO A FALSE ASDE ALERT. ATTEMPTS AT 'RADAR FILTERING' HAVE NOT HELPED. THE CTLR ADVISED THAT PRIMARY TARGETS ARE BARELY VISIBLE. SUPPLEMENTAL INFO: TWR SPECIALIST ADVISED THAT CTLRS ARE REQUIRED TO EVALUATE EACH ALARM. SINCE THERE ARE MANY FALSE ALERTS TARGETS NOT AT KNOWN/PUBLISHED INTXN CROSSING POINTS 'CAN BE IGNORED.' WHAT IS CAUSING THE FALSE MULTIPATH REFLECTION ALERTS IS NOT EXACTLY KNOWN. CONSIDERATION ARE THE CLOSENESS OF THE ASDE ANTENNA TO THE TERMINAL; THE SOFTWARE PROGRAM AND/OR ANTENNA ANGLE. IMPLEMENTATION OF AMASS HAD BEEN DELAYED DUE TO ITS OWN SOFTWARE PROBS AS WELL AS BEING UNABLE TO FILTER OUT FALSE ASDE ALERTS.