TFSR and FDSR are selectable options on newer Whistler Radar Detectors.
TFSR (Traffic Flow Sensor Rejection) - This mode helps to reduce or eliminate common falsing from radar based traffic flow systems and vehicles equipped with radar based collision avoidance systems.
If you want to reduce/eliminate these types of alerts, engage TFSR
FDSR (Field Disturbance Sensor Rejection) – This mode maintains a quick reaction to radar. When radar based collision avoidance systems (FMCW) are detected, your unit will provide a brief 2 beep (less urgent) alert to make you aware this encounter is different than a typical radar. You may notice a standard alert when approaching some radar based road work signs while others provide the 2 beep alert as some utilize CW radar and others utilize FMCR radar.
If you want to remain aware of ALL radar systems but want to reduce the audible alert from FMCW systems, engage FDSR.