Patent ID: 6137406
Filing Date: 2000-10-24
Classification: G01S

Abstract:
A double superheterodyne type microwave detector, comprising:a reception antenna;a first local oscillator;a second local oscillator;reception means for detecting microwaves having prescribed frequencies based on signals obtained by carrying out a first mixing in which the output of the first local oscillator is mixed with the microwaves picked up by the antenna, and a second mixing in which the signals obtained from the first mixing are mixed with the output of the second local oscillator;judgement means for judging whether or not an actual microwave signal which forms a detection target has been detected by the reception means;alarm means for outputting an alarm when the judgement means judges an actual microwave signal to have been received by the reception means; andfirst control means for suspending the first mixing when the reception means detects a microwave signal having a prescribed frequency;wherein the judgement of whether or not the prescribed frequency microwave signal detected by the reception means is an actual microwave signal is carried out by the judgement means based on a detected wave output outputted from the reception means after suspension of the first mixing.