Quadrature detection method, quadrature detection device and radio wave time piece

A quadrature detection device for demodulating a modulation wave from a carrier wave subjected to amplitude modulation or phase modulation, comprising:

• signal processing means for sequentially processing input signals for a one-fourth cycle of the carrier wave;
• adder and subtracter means for adding and subtracting ones of integrated values and average values of the input signals, derived for one cycle of the carrier wave upon the integrating or averaging, to calculate outputs Ik and Qk based on equations expressed as
• Ik=S4k−3+S4k−2−S4k−1−S4k
• Qk=S4k−3−S4k−2−S4k−1+S4k
• where S1, S2, S3, 34 represent the average values and k represents 1, 2, 3, . . . ;
• and
• accumulator means for obtaining sums IN,m and QN,m of the outputs Ik and Qk for an N-cycle of the carrier wave for thereby calculating an in-phase component IN,m and a quadrature component QN,m of the carrier wave based on equations expressed as
• I
• N
• ,
• m
• =
• ∑
• k
• -
• (
• m
• -
• 1
• )
• ⁢
• N
• +
• 1
• mN
• ⁢
• I
• k
• ,
• ⁢
• Q
• N
• ,
• m
• =
• ∑
• k
• -
• (
• m
• -
• 1
• )
• ⁢
• N
• +
• 1
• mN
• ⁢
• Qi
• ,
• ⁢
• m
• =
• 1
• ,
• 2
• ,
• 3
• ,
• …

A radio wave timepiece, comprising:

• timekeeping means for keeping current time in response to a given reference clock;
• a receiving antenna for receiving a standard radio wave having an amplitude modulated in terms of time information representing the current time;
• detection means including quadrature detection means for extracting an in-phase component and a quadrature component of the carrier wave and amplitude calculation means for calculating an amplitude of the carrier wave in response to the in-phase component and the quadrature component of the carrier wave;
• and
• time correction means for demodulating time information in response to the amplitude of the carrier wave for thereby correcting the current time in the timekeeping means based on the time information demodulated by the time correction means.

A radio wave timepiece comprising:

• a quart crystal oscillator oscillating clocks at a given frequency;
• a frequency divider frequency-dividing the clocks with a given frequency division ratio to generate a reference clock;
• timekeeping means counting reference clocks to perform timekeeping for current time;
• a receiving antenna receiving time information multiplexed on a carrier wave of a long wave standard radio wave;
• a quadrature detection device performing quadrature detection of the carrier wave in response to the reference cock for extracting an in-phase component and a quadrature component of the carrier wave and operative to calculate an amplitude of the carrier wave based on the in-phase component and the quadrature component for demodulating time information multiplexed on the carrier wave;
• and
• a time verification circuit for verifying the time information from the quadrature detection device for correcting the current the of the timekeeping means depending on a verified time information.