Abstract: The invention relates to a velocity determination apparatus (1) for determining a velocity of an object (2). A Doppler frequency measuring unit is adapted to measure Doppler frequencies in at least three different frequency directions, wherein a Doppler frequency calculation unit is adapted to calculate a Doppler frequency for a calculation frequency direction being similar to one of the at least three different frequency directions depending on the Doppler frequencies measured for at least two further frequency directions of the at least three different frequency directions. The velocity can then be determined depending on the calculated Doppler frequency and the measured Doppler frequencies. Since in the calculation frequency direction the measured Doppler frequency is not needed for determining the velocity, a reliable velocity can be determined also in the calculation frequency direction, even if the measurement of the Doppler frequency in this calculation frequency direction is disturbed.

Abstract: A demodulating system (100) for demodulating a phase-modulated input signal (Si) comprises: a complex demodulator (110), having a first input (111) for receiving the phase-modulated input signal (Si) and being designed to perform complex multiplication of this signal with an approximation of the inverse of the phase modulation; a spectrum analyzing device (130) receiving the demodulated product signal produced by the complex demodulator (110) and capable of analyzing the frequency spectrum of the demodulated product signal.

Abstract: A method for detecting motion direction of an object (4) comprises the steps of: laser output light (L1) is generated, using a semiconductor laser (2) having a thermal response frequency (fr); the laser is driven with rectangularly modulated DC current (I) having a modulation frequency higher than said thermal response frequency (fr) and preferably higher than twice said thermal response frequency (fr), such as to triangularly modulate the wavelength of the laser output light; the laser output light is directed to the object; a portion of reflected light (L3) is allowed to interfere with light (L0) within the laser; a portion of the laser light is used as measuring beam (5); the frequency spectrum of the measuring beam (5) is analyzed in conjunction with the modulated laser current in order to determine the direction of movement of the object (4).

Abstract: The invention relates to a velocity determination apparatus (1) for determining a velocity of an object (2). A Doppler frequency measuring unit is adapted to measure Doppler frequencies in at least three different frequency directions, wherein a Doppler frequency calculation unit is adapted to calculate a Doppler frequency for a calculation frequency direction being similar to one of the at least three different frequency directions depending on the Doppler frequencies measured for at least two further frequency directions of the at least three different frequency directions. The velocity can then be determined depending on the calculated Doppler frequency and the measured Doppler frequencies. Since in the calculation frequency direction the measured Doppler frequency is not needed for determining the velocity, a reliable velocity can be determined also in the calculation frequency direction, even if the measurement of the Doppler frequency in this calculation frequency direction is disturbed.

Abstract: A method for detecting motion direction of an object (4) comprises the steps of: laser output light (L1) is generated, using a semiconductor laser (2) having a thermal response frequency (fr); the laser is driven with rectangularly modulated DC current (I) having a modulation frequency higher than said thermal response frequency (fr) and preferably higher than twice said thermal response frequency (fr), such as to triangularly modulate the wavelength of the laser output light; the laser output light is directed to the object; a portion of reflected light (L3) is allowed to interfere with light (L0) within the laser; a portion of the laser light is used as measuring beam (5); the frequency spectrum of the measuring beam (5) is analyzed in conjunction with the modulated laser current in order to determine the direction of movement of the object (4).

Abstract: A demodulating system (100) for demodulating a phase-modulated input signal (Si) comprises: a complex demodulator (110), having a first input (111) for receiving the phase-modulated input signal (Si) and being designed to perform complex multiplication of this signal with an approximation of the inverse of the phase modulation; a spectrum analyzing device (130) receiving the demodulated product signal produced by the complex demodulator (110) and capable of analyzing the frequency spectrum of the demodulated product signal.