Patent ID: 7977991

Claim:
An adjacent channel interference detection apparatus that detects adjacent channel interference between broadcast waves of broadcast stations whose frequency bands are adjacent to each other, said adjacent channel interference detection apparatus comprising: a local oscillation unit configured to generate two signals of a predetermined frequency in a free-running state, the two signals of the predetermined frequency being different in phase from each other by 90 degrees; two mixer units configured to mix an input signal respectively with the two signals of the predetermined frequency generated by said local oscillation unit; two low pass filter units respectively connected to outputs of said two mixer units; a rotation judgment unit configured to detect a direction in which a signal point rotates on an IQ plane, according to an I signal and a Q signal outputted respectively from said two low pass filter units; a counter unit configured to count an output of said rotation judgment unit; and a detection unit configured to detect an imbalance in the number of times the signal point rotates in each direction, according to the count by said counter unit.