A dual-band antenna matching system and a method for dual-band impedance matching are provided. The method comprises: accepting a frequency-dependent impedance from an antenna; and, selectively supplying a conjugate impedance match for the antenna at either a first and a second communication band, or a third and a fourth communication band. More specifically, the method comprises: tuning a first tuning circuit to a first frequency; and, simultaneously tuning a second tuning circuit to a second frequency. In response, a conjugate match is supplied to the antenna in the first communication band in response to the first frequency. Simultaneously, the antenna is matched in the second communication band in response to the second frequency. When the first tuning circuit is tuned to a third frequency, and the second tuning circuit is tuned to a fourth frequency, then conjugate matches are supplied for the third and fourth communication bands, responsive to the third and fourth frequencies, respectively.

System and method for dual-band antenna matching

A mismatch detector including a directional device adapted to couple signals across the device and a detector coupled to a port on the directional device and configured to measure a reflected power a second detector coupled to a port on the directional device and configured to measure a transmit power. The mismatch detector may be used in wireless communication devices, including, but not limited to mobile wireless devices, base stations, and communication systems.

Systems and methods for controlling output power in a communication device

A supervisory communications device, such as a headend device within a communications network, monitors and controls communications with a plurality of remote communications devices throughout a widely distributed network. The supervisory device allocates bandwidth on the upstream channels by sending MAP messages over its downstream channel. A highly integrated media access controller integrated circuit (MAC IC) operates within the headend to provide lower level processing on signals exchanged with the remote devices. The enhanced functionality of the MAC IC relieves the processing burden on the headend CPU and increases packet throughput. The enhanced functionality includes header suppression and expansion, DES encryption and decryption, fragment reassembly, concatenation, and DMA operations

Highly integrated media access control

A system for transmitting digital programming includes a program source providing digital information, circuitry for modulating the digital information onto a visual carrier modulated with analog television programming, and a visual transmitter coupled to the modulating circuitry. Using a phase modulation method, the system phase modulates the digital information onto a visual carrier, reduces the baseband frequencies of the phase modulated visual carrier, and amplitude modulates the phase-modulated video carrier onto a video signal. The amplified and encoded video signal are combined with an amplified sound signal and transmitted. Using an additive method, the system modulates the sidebands of the video carrier with the digital information and amplitude modulates the video signal onto the video carrier. The data-modulated sidebands are phase-shifted such that they will be in quadrature with the amplitude-modulated video signal. The system combines the amplitude-modulated video carrier and the data-modulated quadrature sidebands. With a blended multiplicative/additive method, the system provides phase modulation and quadrature sideband addition to provide an optimized result.

Expanded information capacity for existing communication transmission systems

A dirctional signal processing system for beamforming information signals. The system includes an oversampled filterbank, which has an analysis filterbank for transforming the information signals in time domain into channel signals in transform domain, a synthesis filterbank and a signal processor. The signal processor processes the outputs of the analysis filterbank for beamforming the information signals. The synthesis filterbank transforms the outputs of the signal processorto a single information signal in time domain.

Directional audio signal processing using an oversampled filterbank

A voltage tunable bandpass filter consisting of a plurality of parallel resonators electromagnetically coupled and having tuning diodes coupled to a first end. The resonators are DC isolated at a second or RF grounded end of each resonator. A voltage source reverse biases the tuning diodes from the second or less critical end of the resonators.

Voltage tunable bandpass filter

A method and apparatus for automatic tuning calibration of electronically tuned filters which comprises a programmable frequency generator for producing a calibration frequency signal, a filter for filtering the calibration frequency signal, a detector for producing a detector voltage, a processor for programming the frequency generator to specific test frequencies and for producing a stepped filter tuning voltage and storing the detector voltage in response to the stepped filter tuning voltage, and a converter for digital-to-analog conversion of the stepped filter tuning voltage. Calibration frequency signal versus tuning voltage responses are stored for a number of calibration iterations within the usable range of the filter and the resulting table can be used to determine the correct tuning voltage for the filter when operating at any frequency within the usable filter range.

Method and apparatus for automatic tuning calibration of electronically tuned filters

A radio frequency amplifier includes a bipolar and a field effect transistors (FET) which are cascoded for efficient operation and simultaneous gain control. Bias circuitry is connected to the control electrode of the FET to stabilize the output bias thereof. Negative feedback circuitry is connected between the output electrode of the FET and the control electrode of the bipolar transistor to stabilize the other bias levels within the circuitry. An AGC circuit is connected to the feedback circuitry to provide an automatic gain control function.

Low noise ultra high frequency amplifier having automatic gain control

A direct conversion receiver (DCR)(10) comprises amplitude modulated interference (AMI) nulling circuitry (32) for achieving enhanced cancellation of AMI. The AMI nulling circuitry (32) includes a first signal processor (42) and a second signal processor (44) for processing first and second differential output signals, respectively, from a mixer (24a). The first signal processor (42) includes an adjustable transfer function that is controlled by a controller (50). The controller (50) adjusts the transfer function of the first signal processor (42) to equalize the magnitudes of AMI components in the first and second differential output signals. The first and second differential output signals are then combined in a manner which cancels the equalized AMI components.

Method and apparatus for reducing amplitude modulated interference in a receiver

A receiver which converts the RF carrier to a very low frequency and incorporates a PLL demodulator which allows the IF to be AC coupled. This PLL demodulator does not include the IF filters. The bandwidth of the PLL demodulator is wide enough to demodulate FM. Also, components of the receiver can be switched to a transmission mode capable of FM or PSK modulation with a simple circuit. Finally, the receiver includes an AM or PSK coherent amplitude detector which is modified into an imageless spectrum analyzer.

Michael Newton Pickett

Papers

Voltage tunable bandpass filter

Method and apparatus for automatic tuning calibration of electronically tuned filters

Low noise ultra high frequency amplifier having automatic gain control

Method and apparatus for reducing amplitude modulated interference in a receiver

Nearly DC IF phase locked transceiver