36 results about "FM transmitter" patented technology

An accessory for an electronic device detects manipulation of a user input of the device and alters an operating parameter of the accessory in response to the detected manipulation of the device's controls. The accessory is preferably an FM transmitter designed to be coupled to a portable media player such that an audio signal from the player is broadcast by the accessory. The user controls of the player can be used to select a transmission frequency of the accessory. The accessory can also preferably control the display of the device such that an image corresponding to the selected transmission frequency is generated by the accessory and displayed on a screen of the player.

The invention discloses a radio system electromagnetic interference test system which is installed in a semi-anechoic chamber and comprises an amplitude modulation transmitter, a frequency modulationtransmitter, a receiver, a first transmitting antenna, a second transmitting antenna and a receiving antenna. The first transmitting antenna is connected with the amplitude modulation transmitter, thesecond transmitting antenna is connected with the frequency modulation transmitter, and the receiving antenna is connected with the receiver. The amplitude modulation transmitter is in communicationconnection with the receiver through the first transmitting antenna and the receiving antenna. The frequency modulation transmitter is in communication connection with the receiver through the secondtransmitting antenna and the receiving antenna. The amplitude modulation transmitter is installed at a first preset distance of the frequency modulation transmitter, and the receiving antenna is arranged at a position where the vertical distance between the amplitude modulation transmitter and the frequency modulation transmitter is a second preset distance. The invention also discloses a radio system electromagnetic interference test method, which can effectively eliminate other electromagnetic interferences in the space and reduce the hardware requirements of the test equipment, thereby effectively reducing the test difficulty and improving the accuracy of the test result.

There is disclosed a multi-unit communication system having, at each unit, both an FM receiver and a FM transmitter as well as a digital receiver and transmitter. The primary communication of an information signal from the system to a plurality of mobile hand held transceivers is through the FM transmitters. The digital receiver and transmitter provides a back channel to provide communication of the message throughout the set of units to assure that the information is available at each unit for conversion from digital to analog form so as to be broadcast by the FM transmitter.

Digital values representing an audio signal are formed in a FM transmitter. The deviation of the amplitude of the audio signal as represented by the digital values, from a reference amplitude level, is measured. The audio signal is filtered based on the deviation measured by processing the digital values, with the filtering designed to filter different frequency components of the audio signal with different respective magnitudes. Another set of digital values representing the filtered audio signal is generated, and used to frequency modulate a carrier signal to generate a FM signal. Over-modulation of the FM signal is thereby controlled.

The invention relates to a safety alarm system and method in a road tunnel. The system is composed of a warning board (1), a bracket (2), a fluorescent strip (3), a camera (5), a shooting speed-measuring device (6), a loudspeaker box (7), a deceleration strip groove (8), a bottom plate (9), a deceleration strip (10), a lifting device (11), a puncturing device groove (12), a separation board (13),a steel nail plate (14), a lighting lamp (15), a signal receiving processor (16), a solar cell panel (17), a through hole (18), a lane light (19), and a frequency-modulation transmitter. The bracket is connected to the lower end of the warning board; the camera is installed at the top inside the tunnel; the loudspeaker box and the signal receiving processor are arranged at the center of the top inside the tunnel; the deceleration strip groove is formed in the bottom of the tunnel; and the puncturing device groove is formed in the right side of the deceleration strip groove.

The invention discloses a radio system electromagnetic interference testing system, which is installed in a semi-anechoic chamber and includes: an AM transmitter, a FM transmitter, a receiver, a first transmitting antenna, a second transmitting antenna and a receiving antenna; the first transmitting antenna It is connected with the AM transmitter, the second transmitting antenna is connected with the FM transmitter, and the receiving antenna is connected with the receiver; the AM transmitter is connected with the receiver through the first transmitting antenna and receiving antenna, and the FM transmitter is connected through the second transmitting antenna, receiving The antenna is communicatively connected to the receiver; the AM transmitter is installed at a first preset distance from the FM transmitter, and the receiving antenna is set at a second preset distance from the AM transmitter to the FM transmitter. The invention also discloses a radio system electromagnetic interference test method, which can effectively eliminate other electromagnetic interference existing in the space, reduce hardware requirements of test equipment, thereby effectively reducing test difficulty and improving test result accuracy.

The present invention provides an intelligent vehicle-mounted network connection terminal, an audio information sending method, and a noise reduction method, including: a control module, an audio processing module, and an FM transmitting module; wherein, the control module is used to send digital audio information to be played to the audio processing module, and send a state control signal to the FM transmitter module according to the working status information of the audio processing module; the audio processing module is used to convert the received digital audio information into analog audio information, and send the analog audio information to the FM transmitter module , and feed back the working status information of the audio processing module to the control module; the FM transmitting module is used to modulate the analog audio information, transmit the modulated signal through the corresponding frequency point, and determine the working status according to the status control signal sent by the control module . In the present invention, when there is no audio information to be transmitted, the FM transmission module is set to a MUTE state, thereby effectively reducing the influence of background noise on the user's hearing experience.

The invention discloses a data security signal transmission system of the Internet of Things, which includes a photoelectric conversion amplifier circuit, a voltage comparison circuit, a sine wave oscillation circuit and a frequency modulation transmission circuit. The signal is sampled and its optical power is converted into a fiber optic voltage. The voltage comparison circuit compares the fiber optic voltage with the upper limit of the standard voltage and the lower limit of the standard voltage. The power detection signal is obtained, the sine wave oscillation circuit determines the frequency of the sine wave modulation signal according to the positive and negative of the power detection signal, and the frequency modulation transmitting circuit performs FM modulation on the sine wave modulation signal to obtain the power conditioning signal, and transmits the power conditioning signal to the radio and television material Network power monitoring and control terminal, so that the radio and television Internet of Things power monitoring and control terminal can adjust the optical power of the radio and television Internet of Things optical transmitter.

The invention discloses a frequency modulation transmitting device. The device comprises a single-chip microcomputer module, an FPGA module, an analog-to-digital conversion module, a phase discrimination module, a loop filtering module and a voltage controlled oscillation module. The single-chip microcomputer module performs frequency setting on the phase discrimination module according to a preset working mode to adjust the input voltage of the phase discrimination module acting on the coarse tuning end of the voltage controlled oscillation module, so that the output signal of the voltage controlled oscillation module is the same as the setting value of the phase discrimination module. The FPGA module performs high-speed sampling on the received external data signals and controls the input voltage of the digital-to-analog conversion module according to the frequency offset control word of the code rate corresponding to the received external data signal. The digital-to-analog conversion module controls the input voltage of the digital conversion module acting on the fine tuning end of the voltage controlled oscillation module according to the current input voltage, so that the precision of the output signal of the voltage controlled oscillation module reaches a preset value. According to the frequency modulation transmitting device, coarse tuning and fine tuning of the output signal of the voltage controlled oscillation module is realized, and the effects that the output signal frequency of the transmitting device is stable, the spectrum purity is high, and the resonance clutter suppression degree is high are achieved.