3 results about "Carrier modulation" patented technology

The invention relates to the field of strong directivity parametric array loudspeaker. In the loudspeaker, audio signal and ultrasonic carrier signal are modulated, and by utilizing the strong directivity of the ultrasonic carrier, the audio signal beam with strong directivity is obtained. In particular, the invention relates to a parametric array loudspeaker and a method for treating signal thereof; the method uses conversion transducer units with different frequencies to form a transmitting array to transmit the ultrasonic carrier modulation signal after power amplification, thereby improving ultrasonic radiant intensity, outputting stable enough signal, making audio signal select a proper carrier frequency, further expanding frequency response of audio frequency and improving loudspeaker performance; and the method can be widely applied to the filed of controlling noise jamming.

The invention provides a power line carrier modulation method, a demodulation method, a circuit and a chip. The modulation method comprises the following steps of: detecting narrow-band nongaussian noise frequency in a power line; selecting non-noise frequency from a preset carrier frequency band as modulation carrier frequency; generating a modulation carrier according to the modulation carrier frequency; modulating a digital signal to be modulated to the modulation carrier to generate a power line carrier signal. By using the modulation method, the narrow-band nongaussian noise frequency can be avoided, the change of noise environment of the power line can be adapted, and the quality of power line communication can be improved.

The invention discloses a power line carrier communication apparatus used for overocean communication. The apparatus comprises a carrier transmitting terminal, a carrier receiving terminal and a neutral buoyancy cable. The carrier transmitting terminal emits a carrier signal and the carrier signal is transmitted to the carrier receiving terminal through the neutral buoyancy cable so as to be received. The carrier transmitting terminal comprises an upper computer serial interface, a master control chip, a power line carrier modulation module, an emission coupling circuit and a coupling transformer. The carrier receiving terminal comprises the upper computer serial interface, the master control chip, the power line carrier demodulation module, a receiving coupling circuit and a decoupling transformer. The neutral buoyancy cable is a light-buoyancy-material counter-weight coaxial cable. In the invention, during communication, a special communication cable is not added so that engineering cost and construction difficulty are greatly reduced; multichannel coupling is used so as to reach a high parallel communication rate; independent coupling and decoupling circuits of each channel guarantee effective modulation and demodulation of each independent channel carrier wave; and the special coaxial cable is used so that communication reliability is increased.