22 results about "Radio frequency signal" patented technology

A swimming pool drowning prevention safety system. The swimming pool drowning prevention safety system comprises: an article wearable by a person, a radio frequency transmitting device coupled to the article for transmitting a radio frequency signal, a microprocessor controlled radio frequency receiving station for receiving the radio frequency signal from the radio frequency transmitting device when the radio frequency transmitting device is within a user adjustable radio reception range of the radio frequency receiving station, and an alert signaling device coupled to the radio frequency receiving station for signaling when the person wearing the article has come within the user adjustable radio reception range of the radio frequency receiving station. The swimming pool drowning prevention safety system is further comprised of an adjustable gain control for varying the RF sensitivity of the radio frequency receiving station, and an RF sensitivity trigger circuit coupled to an audio messaging system for broadcasting at least one selected alert message. The swimming pool drowning prevention safety system further comprises telephone circuitry connection equipment for automatically connecting to a telephone system and transmitting the selected alert message. The swimming pool drowning prevention safety system further comprises a microprocessor that controls and integrates operation of the radio frequency receiving station.

In a communication system, an access point in communication with one or more stations identifies a first subset of wireless stations from the set of wireless stations. The first subset of wireless stations is identified based on RSSI values for radio frequency signals received from each of the stations exceeding an RSSI threshold. The first subset of wireless stations is assigned to a first reception window. The access point transmits an identifier of each of the subset of wireless stations and an identifier of the reception window via the radio frequency channel.

The invention relates to a final three-route power synthesizing amplifying circuit applied to a power amplifier of a mobile communication base station system. The invention is characterized in that the circuit comprises a first coupler, a first absorption load, a first microstrip line, a Doherty synthesizing amplifier, a fourth microstrip line, a third final amplifier, a seventh microstrip line, a third coupler and a third absorption load. A 0 degree output end of the first coupler is connected to an input end of the Doherty synthesizing amplifier by the first microstrip line; a -90 degree output end of the first coupler is connected to an input end of the third final amplifier by the fourth microstrip line; an output end of the third final amplifier is connected to a 0 degree input end of the third coupler by the seventh microstrip line; an output end of the Doherty synthesizing amplifier is connected to a 90 degrees input end of the third coupler; an output end of the third coupler outputs amplified radio-frequency signals. The circuit satisfies requirement of high efficiency, has low cost, and also guarantees reliable and stable work of power amplifier.

The present invention discloses a method for processing IQ data of radio-frequency remote unit (RRU), the method comprising: after receiving IQ data sent by a baseband processing unit (BBU) via a dual carrier, the RRU conducts parallel processing on IQ data on the dual carrier, modulates the processed dual carrier into a radio-frequency signal and outputs the signal to an antenna terminal. The present invention discloses an IQ data processing system and a radio-frequency remote unit at the same time. The technical solution of the present invention enhances the capability of an active antenna for transmitting data and reduces cost.

The present invention provides a radio frequency (RF) filtering circuit and a plasma processing apparatus employing the RF filtering circuit, wherein the RF filtering circuit comprises a primary filter and a secondary filter, the secondary filter comprises two or more filters connected in parallel, the primary filter is selectively connected to one of the secondary filters through a switch; the RFfiltering circuit further comprises a heating means and a DC power supply for heating the heating means; the primary and secondary filters are disposed between the heating device and the DC power source for filtering radio frequency signals from the heating device into the DC power supply. Utilizing the RF filtering circuit of the present invention may greatly reduce the tuning difficulty, improving the accuracy of the RF filtering circuit.

The invention provides an unfreezing device. The unfreezing device includes a cylindrical body, a device door body, a radio frequency generation module, an upper electrode plate and a lower electrodeplate; the cylindrical body is limited to have an unfreezing cavity having a forward opening and used for placing a to-be-processed object; the device door body is arranged on the forward opening of the unfreezing cavity and used for opening and closing the unfreezing cavity; the radio frequency generation module is configured to generate radio frequency signals; the upper and lower electrode plates are respectively and horizontally arranged on the top and bottom walls of the unfreezing cavity and electrically connected to the radio frequency generation module to generate radio frequency wavesof corresponding radio frequency in the unfreezing cavity according to the radio frequency signals and unfreeze the to-be-processed object in the unfreezing cavity; the cylindrical body and the device door body are respectively provided with electromagnetic shielding characteristics; and the electromagnetic shielding characteristic arranged on the cylindrical body and the electromagnetic shielding characteristic arranged on the device door body are arranged in conductive connection so as to reduce magnetic leakage from the unfreezing device when the device door body is closed. Thus, the magnetic leakage of the unfreezing device can be effectively reduced, and the harmfulness to users can be reduced.

The invention provides a radio frequency digitized modulation method based on DDS and DSP. The method comprises a step of transmitting digital singals obtained by an A/D converter to the DSP. The DSP calculates instantaneous frequency offset of the DDS according to the maximum sampling value and digital signal instantaneous value which are output by the A/D converter and calculates instantaneous frequency control word of the DDS according to bits, clock frequency and radio frequency carrier frequency of the DDS. The DDS carries out frequency modulation on the radio-frequency signals according to the instantaneous frequency control word, and generates frequency-modulated signals. The method realizes complete digitized radio frequency modulation. Compared with an analogue modulation method, the radio frequency digitized modulation method has simple circuits, good consistency and high reliability, and is particularly suitable for high speed frequency-hopping sending channels such as high speed frequency-hopping broadcasting station, short frequency conversion time and high data transmission rate.

The invention discloses a QPSK-DS communication detecting method based on delay multiplication. A system is initialized and begins to scan a target frequency band to amplify signals entering the system from the radio frequency front end, radio frequency signals are converted into fixed middle frequency to be amplified through a difference frequency method, digital signals can be achieved through analog-digital conversion, delay multiplication operation is carried out, digital lowpass filtering is carried out to obtain lowpass signals, and a frequency spectrum of the lowpass signals can be achieved through an FFT algorithm. The QPSK-DS communication detecting method has the advantages of adopting a linear and non-linear processing method to achieve full detection on QPSK-DS communication through simple comprehensive analysis and processing on time frequency domains and being simple to achieve, strong in operability and strong in capacity adapting to low signal to noise ratio. Meanwhile, the method adopts the middle frequency analysis instead of radio frequency or baseband processing to avoid high requirements for performance of processing capacity of a receiver as possible. Furthermore, the method can achieve real-time processing easily and is strong in practicability.

The invention discloses an RFID technology-based book detector and a detection method. The detector comprises an information input module, a main control module, a radio frequency reception/transmission module and an information prompt module, wherein the information input module is used by a user to input information of a target book; the main control module is used for receiving information sentby the information input module and analyzing the information; the radio frequency reception/transmission module is used for sending a radio frequency signal according to an instruction of the main control module, receiving a radio frequency signal, carrying book information, reflected through an RFID label and sensing the radio frequency signal to the main control module; and the information prompt module is used for prompting the user according to the instruction of the main control module. The RFID technology-based book detector and the detection method are simple in principle and easy torealize, and have high cost performance and high popularization value when being compared with intelligent book shelves.

An emergency warning system for warning vehicles and electronic devices is disclosed. The emergency warning system comprises a first system. The first system is provided in a building or highway or road construction zone or in a first vehicle indicative of an emergency vehicle. The first system comprises an actuator, a radio-frequency signal generator communicatively coupled to the actuator. The radio-frequency signal generator is used to generate radio frequency signals at a particular frequency. Further, the first system comprises a transmitter for broadcasting the signals generated by the radio-frequency signal generator. Further, the emergency warning system comprises a second system provided in a second vehicle and at least one electronic device, present within a predefined distance of the first system. In order to warn the approach or presence of the first system, the actuator is actuated to generate and broadcast the radio frequency signals such that the second system and the at least one electronic device receives the signals warning users of the second system and the at least one electronic device of the approach or presence of the first system.

The invention discloses an all-optical sampler, comprising a continuous laser which is used for generating continuous signal light; an optical modulator which is driven by a radio frequency signal and is used for modulating an analog radio frequency signal through combination with the signal light, thereby generating continuous analog signal light; a polarization controller which is used for controlling a polarization state of the analog signal light; a first coupler which is used for allocating the low-power analog signal light into two ways of light according to a proportion; a Mach-Zehnder interferometer, wherein a first interference arm and a second interference arm of the Mach-Zehnder interferometer are used for receiving the two ways of analog signal light allocated by the first coupler; and a second coupler which is used for receiving the analog signal light output by the Mach-Zehnder inter-ferometer, coupling the analog signal light and then outputting sample signal light. According to the all-optical sampler, through utilization of cross-phase modulation effect of pump light for the analog signal light, the phase difference of the signals on the two interference arms is changed, so transmittance of the signals is changed; when the pump light exists, the signals are transmitted; and when the pump light does not exist, the signal transmittance is 0, thereby sampling the signals.

The invention discloses an intermediate frequency direct current detuning calibration DCOC circuit applied to a radio frequency signal receiver, the intermediate frequency direct current detuning calibration DCOC circuit comprises an operational amplifier OPA1, an NMOS transistor M1, an NMOS transistor M2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1 and a capacitor C2, one output end of the operational amplifier OPA1 is connected with the resistor R2, and two ends of the capacitor C1 are respectively connected with the output end and an in-phase input end of the operational amplifier OPA1. The other output end of the operational amplifier OPA1 is connected with the resistor R4, and the two ends of the capacitor C2 are connected with the output end of the operational amplifier OPA1 and the inverted input end of the operational amplifier OPA1 respectively. The source electrode of the NMOS transistor M1 is connected with the in-phase input end of the operational amplifier OPA1, and the drain electrode of the NMOS transistor M1 is connected with one end of the resistor R1. The source electrode of the NMOS transistor M2 is connected with the inverted input end of the operational amplifier OPA1, and the drain electrode of the NMOS transistor M2 is connected with one end of the resistor R3. According to the invention, low direct-current offset calibration high-pass turning frequency and small layout area can be realized, the overall area of a chip is reduced, and the manufacturing cost is reduced.

A gate is pivotally mounted on an upstanding post located adjacent a juncture of intersecting travel paths. To prevent collisions of persons and/or vehicles moving along the intersecting travel paths at the travel path juncture, a kinetic energy harvesting switch is carried by the upstanding post and has a spring-projected push button or plunger-type operator that is depressed relative to a housing of the switch when the gate begins to open to admit a person and/or a vehicle to the travel path juncture. Energy harvested by the switch is utilized to transmit a radio frequency signal that can be received by a device that displays a visual warning and/or emits an audible warning, advising that collision avoidance measures are likely to be needed to prevent a collision at the travel path juncture.

The invention discloses a microwave power amplifier capable of realizing polarization mode selection, which comprises a power divider, a first amplification branch consisting of a first phase shift control module and a first amplifier module, a second amplification branch consisting of a second phase shift control module and a second amplifier module, and a 90-degree bridge, a first signal and a second signal which are respectively generated by the power divider output to the first amplification branch and the second amplification branch are input to the 90-degree bridge, and radio frequency signal output is carried out by the horizontal polarized antenna and the vertical polarized antenna which are connected with the 90-degree bridge. The working states of the first amplifier module and the second amplifier module are controlled by controlling the phase shift quantity output of the first phase shift control module and the second phase shift control module, so that output control of circularly polarized waves, horizontal polarization, vertical polarization, linear polarization, left-hand circular polarization and right-hand circular polarization is realized, low-cost multi-polarization selection is realized, and the multi-polarization selection is realized. The problem of power loss during horizontal polarization and vertical polarization is solved.

The invention relates to a mobile terminal. The mobile terminal comprises a Type-C interface, a radio frequency assembly, a first switch assembly and an antenna, wherein the radio frequency assembly is connected with the first switch assembly; the first switch assembly is also connected with the antenna and a target pin of the Type-C interface. According to the technical scheme provided by the embodiment of the invention, the first switch assembly is arranged in the mobile terminal, and the first switch assembly is connected with the radio frequency assembly and is also respectively connectedwith the built-in antenna of the mobile terminal and the target pin of the Type-C interface, so on one hand, a radio frequency signal can be transmitted through the built-in antenna; on the other hand, the radio frequency signals can be transmitted through the Type-C interface, and the mobile terminal can select a proper transmission path of the radio frequency signals according to actual requirements, so that the transmission rate of the radio frequency signals is improved, the signal quality of the mobile terminal is improved, and meanwhile, the function of transmitting the radio frequency signals through the Type-C interface is expanded.

The invention discloses a high-frequency multi-protocol high-power reader-writer for radio frequency identification and belongs to technologies in the radio frequency identification field. The reader-writer comprises a radio frequency base station circuit, a microcontroller and a turning circuit, wherein the tuning circuit is connected with the radio frequency base station circuit, and an antennais connected to the tuning circuit; a first access and a second access are connected between the tuning circuit and the radio frequency base station circuit; the first access comprises a first demodulating circuit and a first amplifying circuit which are connected in series; the second access comprises a second demodulating circuit and a second amplifying circuit which are connected in series; anda radio frequency signal generated by the radio frequency base station circuit is sent out by the antenna after passing through the tuning circuit, and the signal received by the tuning circuit is transmitted to the radio frequency base station circuit through the first access or the second access. The technical scheme has the advantages that functions of the reader-writer are highly integrated,the reader-writer can read and write radio frequency cards adopting a TYPE A protocol and a TYPE B protocol, and the reader-write is high in extensibility and adaptability.

The invention relates to an antenna system of switchable external antennas. The antenna system comprises a plurality of built-in antennas, a switching circuit, an external antenna control circuit anda first external antenna connector. The built-in antennas include at least a first built-in antenna and a second built-in antenna, and the first built-in antenna and the second built-in antenna are used for receiving or transmitting radio frequency signals. The switching circuit is used for switching between the first built-in antenna and the second built-in antenna to receive or transmit the radio frequency signals. The external antenna control circuit is used for transmitting a control signal to the switching circuit. When the first external antenna connector is connected with an external antenna, the external antenna control circuit transmits the control signal of a first logical electrical level to the switching circuit, and the switching circuit switches to the external antenna to perform the function of receiving or transmitting the radio frequency signals.