251 results about "Frequency agility" patented technology

A data-modulated ultra wideband transmitter that modulates the phase, frequency, bandwidth, amplitude and / or attenuation of ultra-wideband (UWB) pulses. The transmitter confines or band-limits UWB signals within spectral limits for use in communication, positioning, and / or radar applications. One embodiment comprises a low-level UWB source (e.g., an impulse generator or time-gated oscillator (fixed or voltage-controlled)), a waveform adapter (e.g., digital or analog filter, pulse shaper, and / or voltage variable attenuator), a power amplifier, and an antenna to radiate a band-limited and / or modulated UWB or wideband signals. In a special case where the oscillator has zero frequency and outputs a DC bias, a low-level impulse generator impulse-excites a bandpass filter to produce an UWB signal having an adjustable center frequency and desired bandwidth based on a characteristic of the filter. In another embodiment, a low-level impulse signal is approximated by a time-gated continuous-wave oscillator to produce an extremely wide bandwidth pulse with deterministic center frequency and bandwidth characteristics. The UWB signal may be modulated to carry multi-megabit per second digital data, or may be used in object detection or for ranging applications. Activation of the power amplifier may be time-gated in cadence with the UWB source thereby to reduce inter-pulse power consumption. The UWB transmitter is capable of extremely high pulse repetition frequencies (PRFs) and data rates in the hundreds of megabits per second or more, frequency agility on a pulse-to-pulse basis allowing frequency hopping if desired, and extensibility from below HF to millimeter wave frequencies.

The present invention is a hybrid RF-digital signal processor-based filter for multiband radio architectures systems capable of spectrum re-farming and software defined radios. It performs low-loss frequency agile multiple notch filtering at RF where a large dynamic range exists at a filter input between signals in a stopband and passband. It is a frequency dependent signal attenuation apparatus having two paths connected together by directional couplers. The first path comprising a component such as a delay component or duplexer. The second path comprising a bandstop filter connected to a down converter, a digital filter, and an up converter. At the output of a power amplifier, the invention can be used to attenuate spurs, or noise within bands with strict emission constraints. At the input of a low noise amplifier, the invention can be used to attenuate blockers and transmitter noise outside of the receiver passband.

A frequency-agile optical transceiver includes a shared local oscillator (LO), a coherent optical receiver and an optical transmitter. The LO operates to generate a respective LO optical signal having a predetermined LO wavelength. The coherent optical receiver is operatively coupled to the LO, and uses the LO signal to selectively receive traffic of an arbitrary target channel of an inbound broadband optical signal. The optical transmitter is also operatively coupled to the LO, and uses the LO to generate an outbound optical channel signal having a respective outbound channel wavelength corresponding to the LO wavelength.

Systems, methods, and apparatuses are provided for spectrum-sensing cognitive radios that are operative to detect and utilize available RF spectrum resources. The spectrum-sensing cognitive radios include at least one antenna and a frequency-agile radio front-end module in communication with the at least one antenna and configured to transmit and receive radio frequency signals via the at least one antenna. In addition, a spectrum-sensing module, which may include one or both of coarse-sensing and fine-sensing modules, may be in communication with the at least one antenna and be configured to generate RF spectrum usage information. A medium access control (MAC) module is operative to receive the RF spectrum usage information from the spectrum-sensing module. Based upon the received RF spectrum usage information, the MAC module is operative to direct a frequency of operation of the radio front-end module based at least in part on the received spectrum usage information.

A frequency-agile optical transceiver includes a shared local oscillator (LO), a coherent optical receiver and an optical transmitter. The LO operates to generate a respective LO optical signal having a predetermined LO wavelength. The coherent optical receiver is operatively coupled to the LO, and uses the LO signal to selectively receive traffic of an arbitrary target channel of an inbound broadband optical signal. The optical transmitter is also operatively coupled to the LO, and uses the LO to generate an outbound optical channel signal having a respective outbound channel wavelength corresponding to the LO wavelength.

This invention provides a method for improved frequency agility and preferably includes transmitting and receiving data on a primary channel; finding a secondary channel substantially free from interference during a period between data transmissions on the primary channel; and transmitting and receiving data on the secondary channel when an unacceptable level of interference is detected on the primary channel. In an alternate embodiment, data is preferably transmitted on a primary and a secondary channel during separate periods of a transmission interval. If an unacceptable level of interference is detected on either the primary or secondary channels, then the other channel is used for data transmission during one of the periods while another one of the periods is used to identify a new channel substantially free from interference to replace the bad channel.

A distributed block frequency converter that combines multiple channel signals into a combined radio frequency (RF) signal suitable for transport via selected media. The converter includes combiners that each combine at least two channel signals into a combined channel signal, an up-converter synthesizer that generates an up-converter local oscillator (LO) signal, up-converter mixers that each mix a combined channel signal with the up-converter LO signal to provide a corresponding intermediate frequency (IF) signal, bandpass filters that each filter an IF signal, down-converter synthesizers, down-converter mixers that each mix a down-converter LO signal with a corresponding filtered signal to provide a corresponding RF signal, and an RF combiner that combines the RF signals into a single RF signal. The down-converter synthesizers are adjustable to achieve frequency agility on a block by block basis.

A subscriber platform for broadband communication, according to various aspects of the present invention, includes an antenna, a plurality of transceivers, and a processor. The antenna supports communication via a plurality of directional beams. The plurality of frequency agile transceivers operate simultaneously, each transceiver being coupled to the antenna for communication via a respective directional beam. The processor is coupled to the plurality of transceivers. And, the transceivers are coupled to the antenna to communicate data among the directional beams as directed by the processor, communication including directional diversity and frequency diversity.

The invention describes a method of altering the transmitted frequency used in an ultrasonic ranging system for liquid level measurement in a fuel tank. The frequency agility of the system is an important component of performing liquid level measurement in an enclosed vessel.