Abstract: A magnetic sensor detects presence or absence of a magnetic field and its polarity. South pole and north pole magnetic fields are respectively detected by the south pole detection operation and the north pole detection operation. A signal processing circuit of the magnetic sensor performs a unit operation including at least one of the south pole detection operation and the north pole detection operation repeatedly at an interval. In this case, if the south pole is detected in the i-th unit operation, the south pole detection operation is performed first in the (i+1)th unit operation. If the south pole is detected in the south pole detection operation, the north pole detection operation is not performed in the unit operation. If the north pole is detected in the i-th unit operation, operations are performed oppositely to the above.

Abstract: A magnetic sensor detects presence or absence of a magnetic field and its polarity. South pole and north pole magnetic fields are respectively detected by the south pole detection operation and the north pole detection operation. A signal processing circuit of the magnetic sensor performs a unit operation including at least one of the south pole detection operation and the north pole detection operation repeatedly at an interval. In this case, if the south pole is detected in the i-th unit operation, the south pole detection operation is performed first in the (i+1)th unit operation. If the south pole is detected in the south pole detection operation, the north pole detection operation is not performed in the unit operation. If the north pole is detected in the i-th unit operation, operations are performed oppositely to the above.

Abstract: A pre-emphasis filter emphasizes a high-frequency component of an input audio signal. A limiter circuit detects that the output signal from the pre-emphasis filter reaches a predetermined upper limit level. A filter adjusting circuit changes the frequency characteristic of the pre-emphasis filter when a limit operation is generated in the limiter circuit.

Abstract: A stereo modulator converts an audio signal to a stereo composite signal. A frequency modulator receives the stereo composite signal and modulates the frequency of a carrier wave using the stereo composite signal as a modulation signal. An amplitude modulator modulates the amplitude of a sub-carrier by using, as a modulation signal, a difference signal between an L-channel and an R-channel of the audio signal. A first adder adds an output of the amplitude modulator with a sum signal of the L-channel and R-channel. A first multiplier multiplies an output of the first adder with a first variable coefficient. A second multiplier multiplies a pilot signal with a second variable coefficient. A second adder adds outputs of the first and second multipliers and outputs the resultant. A modulation degree adjuster adjusts the amplitude of the stereo composite signal and outputs the resultant signal to the frequency modulator.

Abstract: A data generating unit sets a predetermined value to a data item, which can be made as a reference for tuning at a receiver, so as to generate data of RDS/RBDS format. A frequency modulator modulates the frequency of the data of the RDS/RBDS format generated by the data generating unit, and outputs the frequency-modulated data. The data item may be a program type. The program type is set independently of the type of the data transmitted from the FM transmitter. The receiver tunes with the value of the program type set to the predetermined value.

Abstract: When main power is turned on by a switch SW, a pulse shaper 12 feeds a pulse signal having a pulse width Tp through an OR circuit 14 to a power supply circuit 2a to turn it on. Moreover, a delay generator 13a gives the pulse signal a delay and then feeds it to a control signal generator 15a so that a microcomputer 3 is turned on with a delay corresponding to the length of time required by the power supply circuit 2a to start up.

Abstract: When main power is turned on by a switch SW, a pulse shaper 12 feeds a pulse signal having a pulse width Tp through an OR circuit 14 to a power supply circuit 2a to turn it on. Moreover, a delay generator 13a gives the pulse signal a delay and then feeds it to a control signal generator 15a so that a microcomputer 3 is turned on with a delay corresponding to the length of time required by the power supply circuit 2a to start up.