Patent Document ID: 7714774
Application ID: 11851038
Patent Status: 1

Claim One:
1. A false lock filter circuit for a pulsed altimeter, the circuit comprising: a low pass filter having a relatively low bandwidth (LBW LPF) having an input coupled to receive a detector output; a low pass filter having a relatively high bandwidth (HBW LPF) having an input coupled to receive the detector output; and a false lock controller coupled to receive outputs from the LBW LPF and HBW LPF, the false lock controller configured to: sample the outputs of the LBW LPF to detect a first signal above a threshold level; sample the outputs of the HBW LPF based on the detection of the first signal; compare HBW LPF samples to a defined signal level to determine the percentage of HBW LPF samples on one side of the defined signal level; and compare determined percentage with a defined percentage to determine if the first signal is a valid target.