Page 6 : Filtering
We feel that the most important feature of a radar detector is its ability to filter out stray harmonic frequencies that would also set off your radar detector as a "false alert".
X-band is the worst frequency for false alerts for radar detectors as everything from automatic door openers at supermarkets, alarm systems and other microwave devices share this frequency. K band false alerts also occur and today many garage door manufacturers are using this frequency for their transmitters.
Most of the cheaper radar detectors have no filtering and they will be set off as you pass every supermarket, bank and microwave tower, and it will come to the point that you start ignoring the alerts, even when it is a real one.
Escort has introduced "Truelock" in their new Escort 9500i radar detector which enables the driver to lock out known false alert locations based upon the exact frequency of the false alert.
Autoweek magazine reviewed the Valentine 1 radar detector and referred to it as the "Chicken Little" of radar detectors because of all its false alarms and commented that the average user would end up tuning out all alerts.
All the top end units manufactured by Escort and Beltronics have better filtering capabilities and programming options that decrease the false alerts substantially.