137 results about "RF modulator" patented technology

An RF transmitter uses two digital-to-RF conversion modules to convert digital baseband signals into RF signals. In Cartesian mode, baseband signals are conveyed to the conversion modules for RF conversion. In polar mode, baseband signals are converted into amplitude and phase data parts. Phase data part is converted into I and Q data parts to be converted by the conversion modules into RF signals, which are modulated in a power amplifier by amplitude data part through the power supply of the power amplifier. Each digital-to-RF module uses parallel unit cells to perform D/A conversion function and upconversion function by an IF signal. Each unit cell, adapted to receive a control voltage indicative of a data signal value, is a mixer cell type converter having a differential data switch section connected in series to a differential LO-switch pair. LO-switch is further connected in series to a current source.

A presence detection system comprising, among other things, a radio transmitter and receiver is described herein. The transmitter includes a motion detection circuit, a microprocessor, and a radio frequency modulator. The motion detection circuit is configured to direct a motion detected signal to the microprocessor upon the transmitter being moved in a predetermined manner. The microprocessor is configured to generate an encoded message that includes a preamble denoting a beginning of the encoded message, an identification code denoting a type of transmitter, and a check message (such as a checksum) containing information about content of the encoded message. Finally, the radio frequency modulator is configured to modulate the encoded message at a transmitting frequency.

Distributed and highly software reconfigurable CMTS (CMRTS) device, based on MAC and PHY units with FPGA and DSP components, for a HFC CATV network. The various CATV RF modulators, such as QAM modulators, may be divided between QAM modulators located at the cable plant, and remote QAM modulators ideally located at the fiber nodes. A basic set of CATV QAM data waveforms may optionally be transmitted to the nodes using a first fiber, and a second set of IP/on-demand data may be transmitted to the nodes using an alternate fiber or alternate fiber frequency, and optionally using other protocols such as Ethernet protocols. The nodes will extract the data specific to each neighborhood and inject this data into unused QAM channels, thus achieving improved data transmission rates through finer granularity. A computerized “virtual shelf” control system for managing and reconfiguring the FPGA and DSP based CMTRS units is also disclosed.

A method and system for generating a frequency hopping electromagnetic signal based on a baseband data signal includes a frequency hopping pre-compensator. The frequency hopping pre-compensator determines a frequency hopping pre-compensation signal based on a desired frequency hopping sequence. The frequency hopping pre-compensation signal is combined with the baseband data signal to generate a pre-compensated baseband signal. An RF modulator modulates an RF carrier in accordance with the pre-compensated baseband signal to generate a modulated, frequency hopping RF carrier signal. An amplifier may then amplify the RF carrier signal as desired.

Distributed and software reconfigurable remote CMTS (CMRTS) device, based on MAC and PHY units with FPGA and DSP components, for a HFC CATV network. The various CATV RF modulators, such as QAM modulators, may be located entirely at the fiber nodes if desired. Although a basic set of CATV QAM data waveforms may optionally be transmitted to the nodes using a first fiber, in a preferred embodiment, all data may be transmitted to the nodes using other protocols such as Ethernet protocols. The nodes will extract the data specific to each neighborhood and inject this data into the cable portion of the system as RF waveforms, such as RF QAM channels. A computerized “virtual shelf” control system for managing and reconfiguring the FPGA and DSP based CMTRS units, as well as a new type of edge router based all-digital virtual head end (virtual converged cable access platform) is also disclosed.

A processing device includes a plurality of modulators, the plurality of modulators performing modulation according to a first modulation scheme, a combiner configured to combine outputs from the plurality of modulators, and a signal processor configured to receive a bit stream and convert the bit stream into a plurality of input signals for the plurality of modulators such that the combiner generates a modulated output according to a second modulation scheme. The plurality of modulators may be low order modulators and a modulation schemes of the modulated output may include, for example, rotated quadrature phase shift keying (QPSK), pulse amplitude modulation (PAM), high order quadrature amplitude modulation (QAM), and multi-resolution high order quadrature amplitude modulation (M-QAM).

A remote control unit for controlling a locomotive by transmitting signals to a remote receiver mounted onboard the locomotive is provided. The remote control unit includes an input for receiving a signal indicative of a command selected from a set of available commands. A signal transmitting unit transmits a signal indicative of the selected command repetitively to create a succession of signal transmission events. In a first example, each signal transmission event is spaced in time from a previous signal transmission event by a certain time interval having a duration conditioned at least in part on the basis of the selected command. In a second example, each signal transmission event includes a message portion and a header portion and the message portion of the signal has a length conditioned at least in part on the basis of the selected command. In a third example, each signal transmission event is characterized by a signal level conditioned at least in part on the basis of the selected command. The signal transmitting unit includes an RF modulator adapted for modulating data indicative of the selected command to generate a succession of modulated signals, each modulated signal corresponding to a respective signal transmission event in the succession of signal transmission events.

The invention discloses a rapid local oscillator leakage calibrating device facing an IQ modulator. A radio frequency signal source provides a local oscillator signal and a spectrum analyzer is used for measuring amplitude of the local oscillator signal output by an IQ modulator. During actual operation, the radio frequency signal output end of the a radio frequency signal source is connected to a local oscillator signal input end of the IQ modulator; and the spectrum analyzer is connected to the radio frequency signal output end of the IQ modulator. By controlling the IQ modulator, the output level of direct current bias compensation DAC of an internally arranged I path and a Q path are changed for five times, and direct current bias error compensation values of the I path and the Q path of the IQ modulator can be obtained via calculation, thereby further finishing calibration of local oscillator leakage of the IQ modulator.

A method and a highway addressable remote transducer (HART) soft modem device for modulating and demodulating one or more analog signals with HART messages are provided. A phase coherent frequency shift keying (FSK) modulator modulates and transmits the analog signals, and a phase coherent FSK demodulator receives and demodulates the analog signals. The FSK modulator outputs 1 or 0 for transmission. With oversampling and low pass filtering, digital modulation performed by the FSK modulator results in low jitter and a good signal to noise ratio. The FSK demodulator applies a fast energy detect algorithm and dynamically reduces or increases a clock speed of a central processing unit (CPU) of the HART soft modem device for reducing power consumption of the CPU. Furthermore, the HART soft modem device uses direct memory access and runs multiple instances of a HART soft modem integrated within a microcontroller to reduce an overall power consumption.

This invention discloses a method for generating radio signals and wire baseband at the same time by a double-arm modulator and a single-wavelength light source in a radio-on-fiber(ROF) communicastion system and a system for transmitting two kinds of signals simultaneously on a same wavelength by fiber, which utilizes a dual-webbing modulation and a optical filter theory to generate dual-webbing signals and filter ROF mm waves and baseband data signals from down link to be provided to different users, and this invented system is not only used in single-channel ROF system but also used in WDM ROF system.

There are provided a digital RF converter capable of improving a dynamic range and a signal to noise ratio of a transmitter and a digital RF modulator and a transmitter including the same. The digital RF converter may include: a delta-sigma modulated bits (DSMB) sub-block that generates a current magnitude corresponding to least-significant n bits among input signals at a first sampling speed; a least-significant bit (LSB) sub-block that generates a current magnitude corresponding to intermediate k bits among the input signals at a second sampling speed lower than the first sampling speed; and a most-significant bit (MSB) sub block that generates a current magnitude corresponding to most-significant m bits among the inputs signals at the second sampling speed.

A Wireless Neural Data Acquisition System, including a headstage, an RF receiver, an analog-to-digital converter, a digital signal processor, and a communication interface; the headstage including: at least one input pre-amplifier band-pass filter and amplifier, a multiplexer (MUX), an RF Modulator comprising a voltage control oscillator (VCO), a transmitting antenna, and a power supply; the RF receiver including: at least one receiving antenna, at least one bandpass filter, at least one amplifier, at least one attenuator, and an FM Demodulator. Also, wireless neural data acquisition headstage and a device for amplifying a signal. Also, a method of neural data monitoring.

The invention provides an optical transmitter with a hybrid modulation format. The optical transmitter is applied to a passive optical access network and a long-distance optical transmission system, wherein the passive optical access network is formed by integrating a wavelength division multiplexer and an optical branching device. The optical transmitter comprises an I/Q modulator 1, an I/Q modulator 2, a delay line interferometer and a Mach-Zehnder modulator. The I/Q modulator 1 is in cascade connection with the delay line interferometer, then is in cascade connection with the I/Q modulator 2 and lastly, is in cascade connection with the Mach-Zehnder modulator. The two I/Q modulators are respectively provided with two data input ports, and the Mach-Zehnder modulator is provided with one data input port. The optical transmitter is controlled to output an optical signal with the self-adaptation hybrid modulation format by controlling the on-off and the signal amplitude of the data input ports and the bit and the phase position delay of the delay line interferometer. By means of the optical transmitter, QPSK modulation, 8 QAM modulation and circular 16 QAM modulation can be achieved, and hybrid transmission formed by various modulation formats in any proportional mode can also be achieved. The optical transmitter can be applied to complex transmission links under the wavelength division multiplexing passive optical network environment, and the frequency spectrum utilization efficiency can be effectively improved.

An RF modulator supporting wide-band signals includes IQ modulation by interleaving the in-phase and quadrature signals. The modulator can be implemented using an integrated circuit having a baseband in-phase stage that receives an in-phase analog input signal, a baseband quadrature stage that receives a quadrature analog input signal, and a switching mixer having a plurality of switches. The switching mixer receives in-phase and quadrature signals from the baseband in-phase stage and the baseband quadrature stage. The switching mixer produces a differential signal combining the in-phase and quadrature signals by interleaving the signals over a plurality of phases of a carrier period.

A method and apparatus prevents interference between a radio signal from RDS-TMC service provider for receiving traffic and travel data by an RDS-TMC receiver and a radio signal for transmitting audio, text, or image data from an FM modulator. The method includes the steps of starting an operation of the receiver system, stopping an operation of the FM modulator while keeping operation of the RDS-TMC receiver, examining whether an RDS-TMC signal from a service provider is available at a current location, receiving the RDS-TMC signal and retrieving RDS-TMC data therefrom, sending the retrieved RDS-TMC data to an audio/video system, and starting the operation of the FM modulator while allowing to output an FM signal from the FM modulator at allowable frequency bands which are outside of a blocked range to send data to the audio/video system.

An aircraft entertainment system employing a hybrid video distribution system that permits distribution of direct broadcast satellite television programming to passengers of the aircraft. The aircraft entertainment system has a video control center 11, a plurality of groups of set display units 40, and a plurality of audio and video processors 20 that control routing of programming to each seat display unit. A plurality of seat junction boxes 30 may be interposed between the audio and video processors 20 and the groups of seat display units 40. An antenna 12 is receives programming from a satellite, and a splitter 13 generates a plurality of channels of programming received by the antenna 12. A decoder 14 decodes the channels to provide video and audio signals, and an RF modulator 16 modulates the decoded audio and video signals for distribution. Each seat display unit 40 has a keypad 44 for selecting channels and controlling audio volume, a logic circuit 45 for outputting channel addresses of the selected channels, an address decoder 47 for decoding the channel addresses, and a channel display 46 for displaying the number of the selected channel. A video display 53 displays the television programming, and an audio output device reproduces the audio signals. The audio and video processors 20 convert the modulated RF video signals to baseband video for distribution to the seat display units 40. Each processor comprises a plurality of tuners 25, and non-blocking audio crosspoint switches 26, 27 having a predetermined number of audio and video outputs that are a selected multiple of the number of inputs. A processor 28 is coupled to the audio and video crosspoint switches and to the address decoder of each seat display unit for processing the decoded channel addresses and selecting which channels are output to each seat display unit.