| 摘要 |
PURPOSE:To easily and speedily correct a phase error between the output of a directional sensor and the output of a sense amplifier by adjusting the phase adjuster of the output circuit of a sense antenna while the output of the sense antenna has an nearly 90 deg. phase difference from the output of the directional antenna, and thus eliminating a demodulated wave. CONSTITUTION:The outputs of a couple of loop antennas 1 and 2 which are arranged perpendicularly to each other are modulated by balanced modulators 3 and 4 with the mutually 90 deg. out-of-phase outputs of a low-frequency source 5 and inputted to a synthesizer 7. The output of the sense antenna 6, on the other hand, is inputted to the synthesizer 7 through the phase adjuster 9 and a 90 deg. phase shifter 10 and synthesized with the outputs of the modulators 4 and 5. Its output is inputted to a phase detector 16 along with the signal of reference phase of a low-frequency source 5 through a high-frequency amplifier 12, a detector 13, a band-pass filter 14 having its passing and at the output frequency of the low frequency source 5, and an amplifier 15. A signal is applied to a terminal 18, but if the output of the detector 13 varies abruptly, the phase adjuster 9 is controlled with the output of a level detector 17 and the output signal of the amplifier 15 which is detected by a controller 20 is eliminated.
|
