Lucent Technologies Inc.

Arild T Kolsrud

Walter Joseph Kaminski

Carmine James Pagano, Ii

Hui Wu

Norman Gerard Ziesse

Christopher F Zappala

Julio Antonio Garceran

Richard W Dimeo

Sanjay Kumar

A band edge amplitude reduction system changes the filtering characteristics of a receiver based on the amplitude of signal(s) adjacent to an edge of the operating band of the receiver and/or of signals not under the power control of the receiver. For example, the receiver measures the power level over a bandwidth at the band edges of the operating band of the receiver. If the signals adjacent to the operating band are strong enough relative to the signal power within the operating band, overload protection circuitry changes the filtering characteristics of the receiver to improve the attenuation of the signal(s) from the adjacent band(s). In certain embodiments, the overload protection circuitry switches in filter(s) with a narrower bandwidth to attenuate the signal(s) from adjacent band(s) at the edge(s) of the operating band of the receiver, thereby preventing interference with or the overload of the receiver by signals from outside the operating band and/or not under the power control of the receiver.

Band edge amplitude reduction system and method

An amplifier bias system and method has only reduced resonances at least throughout the envelope frequency of the signal to be amplified. Thus, the amplifier bias system can provide bias current to the amplifier with minimal voltage variations over the envelope frequency band, especially during signal peaks. For example, the amplifier bias system can be used as an amplifier gate or drain bias network where the amplifier bias system is coupled between the power supply and the gate or drain terminals of the amplifier. The amplifier bias system can include an amplifier bias filter having an impedance which is relatively low at least throughout the envelope frequency of the input signal and relatively high at radio frequency. Because the amplifier bias filter has an impedance which is relatively low through at least the envelope or baseband frequency of the input signal and relatively high at radio frequency (RF), the voltage will be relatively constant due to the low voltage drops over the bias network from energy within the envelope frequency band. To reduce the propagation of frequency components within the envelope frequency through the amplifier bias system, an energy handling device can filter energy within the envelope frequency, for example by acting as a short to ground for certain frequencies within the envelope frequency. For signal peaks within the envelope frequency, the energy handling device can provide current through the amplifier bias filter to the amplifier.

Amplifier bias system and method

In the method, an emergency broadcast station receives report of an impending or current disaster-related situation from a local authority. The geographic area to be affected by the impending or current disaster-related situation is served by an existing communication system, such as a cellular network. The emergency broadcast station generates a signal representing an emergency broadcast message that contains a frequency of an accessible main emergency channel at the emergency broadcast station, and a priority level classifying the emergent or impending disaster-related situation. The signal is transmitted to one or base stations, each serving a plurality of users of the system, which in turn send the signal to the users. The users tune to the frequency of the channel to receive the emergency broadcast message.

Cellular base station broadcast method and system

A digital transmitter converts a digital signal into analog form with a digital to analog converter (DAC) and uses an analog signal image produced from the DAC to provide an analog signal at a transmission frequency and/or uses a projected analog signal image to produce analog signals for transmission. Rather than removing analog signal images with a low pass filter at the output of the DAC and/or using analog signal images and analog mixers for frequency conversion, the digital transmitter uses the analog signal images from the DAC to produce the analog signals at the desired frequency/frequencies. By setting and/or adjusting the conversion rate for the DAC and/or the digital signal frequency/frequencies, the analog signal images produced from the DAC can be positioned in the desired frequency band(s). For example, the digital transmitter can position the digital signals within non-overlapping portions of a conversion bandwidth defined as one-half the conversion rate for the DAC. When the digital signals are converted into analog form, the DAC produces analog signal images periodically repeated at multiples of one-half the conversion rate such that analog signal images are produced at the appropriate frequency band(s) for amplification and transmission.

Digital transmitter system and method

A method and an apparatus are provided for filtering a substantially square wave signal. At least a portion of the substantially square wave signal is applied to a first filter adapted to pass a range of frequencies adjacent the fundamental frequency and produce a first filtered signal. At least a portion of the substantially square wave signal is also applied to a plurality of second filters, where each of the second plurality of filters is adapted to pass a range of frequencies adjacent an odd harmonic component of the fundamental frequency and produce a second filtered signal. The first signal and the plurality of second filtered signals are combined to produce a representation of a square wave signal having a frequency substantially corresponding to the fundamental frequency.

Method and apparatus for filtering a clock signal

A receiver receives analog signals at radio frequency (RF), and the RF analog signals are converted into the digital domain. As such, the receiver does not require frequency conversion stage(s) prior to analog to digital conversion. For example, the receiver can comprise at least one antenna(s) which receives radio frequency (RF) analog signals at different frequency bands. The analog RF signals are provided to a single analog to digital (A/D) converter, and the A/D converter converts the analog RF signals at the different frequency bands into digital signals within the Nyquist bandwidth. By properly selecting the sampling rate of the A/D converter for the RF analog signals, the A/D converter can produce replicas of the different frequency bands of the analog signals in non-overlapping portions of the Nyquist bandwidth.

Receiver system using analog to digital conversion at radio frequency and method

A receiver provides received analog signals to a plurality of channel branches, and on at least one of the channel branches, the frequency of the received analog signals is adjusted independent of the relative positions of the corresponding analog signals in the radio frequency (RF) spectrum. The analog signals on the channel branches are then combined, and the combined analog signals are converted into the digital domain. For example, the receiver comprises at least one antenna(s) which receives radio frequency (RF) analog signals. A channel branch arranger receives the analog RF signals from the antenna(s) and provides the RF analog signals to a plurality of channel branches. A frequency conversion arrangement comprising at least one frequency converter on at least a respective one of the channel branches adjusts the frequency band of the analog RF signals on the respective channel branch independent of the relative positions of the corresponding analog signals in the RF spectrum of the different channel branches. The analog signals on the channel branches are combined, and a single analog to digital converter converts the combined analog signals into digital signals. In converting the composite analog signals into the digital domain, the frequency bands of the analog signals are positioned in a plurality of Nyquist zone channels in the digital domain. By properly selecting the frequency bands for the analog signals on the channel branches and the sampling rate for the A/D converter, the available bandwidth for the A/D converter can be more efficiently used, and/or time coherence and/or phase coherence can be provided.

Multiple branch receiver system and method

An analog to digital conversion (A/D) system produces a corrected output of an analog to digital (A/D) converter using at least one past signal sample. For example, the A/D system estimates a reference value or point, such as a reference amplitude, for the at least one past sample. In response to an indication that the A/D converter is saturated, the A/D system uses the reference value to predict a next reference value, such as a next amplitude value, from which a corrected digital sample value is produced to replace the saturating sample.

Method and apparatus for performing analog-to-digital conversion using previous signal sample(s)

The high-power selective signal attenuator includes an attenuator attenuating analog main signals, and a first analog-to-digital converter converting output of the attenuator to digital. A digital-to-analog converter reconverts the digital output of the first ADC to analog, and a cancellor receives the main signals and the analog output from the DAC. The cancellor cancels the analog output of the DAC from the main signals to substantially eliminate high-power signals. A second ADC receives the output of the cancellor and generates a digital output. Based on the digital output, control circuitry dynamically controls the attenuation of the attenuator to prevent saturation of the second ADC and to improve information throughput.

High-power selective signal attenuator and method of attenuation

An analog-to-digital (A/D) converter system which converts an attenuated analog input signal into a digital value and shifts the position of the digital value within the digital output depending on the attenuation of the analog input signal. For example, in response to an analog input signal which saturates a first A/D converter, a second A/D converter receives and converts an attenuated analog input signal, and the output of the second A/D converter is used to produce the more significant bits of the digital output value to convert a higher amplitude range (power or voltage level range) for the analog input signal. In another example, a level detector can detect the amplitude of the analog input signal and provide an indication of the amplitude of the analog input signal. In response, the analog input signal is attenuated and provided to an A/D converter. The A/D converter converts the attenuated analog input signal and produces a digital value as the bits of the digital output where the position of the digital value within the digital output depends on the attenuation of the analog input signal.

Method and apparatus for analog-to-digital conversion using attenuated analog signals

Piezoelectric crystals are arranged to function as variable resonators. In one embodiment, three crystals are arranged as an array, with a center crystal between two outer crystals. An electrical excitation of the outer crystals causes a mechanical displacement in the crystals along a common axis. This displacement squeezes the center crystal, resulting in a shift of the crystal's resonant frequency. By this arrangement, signals input to the outer crystals vary the resonant properties of the inner crystal.

Piezoelectric array devices

An analog-to-digital (A/D) converter system converts an analog input signal into a digital output value by combining a plurality of digital sample values. For example, an A/D converter converts an RF analog signal into digital sample values. The A/D system comprises averaging circuitry which takes the average of N digital sample values from the A/D converter. The average is produced as the digital output value for digital processing circuitry. The signal to noise ratio (SNR) of the A/D system is thereby increased because in the averaging process noise components tend to cancel due to their random nature. The increase in the SNR provided by averaging the digital sample values enables the use of higher sampling rates because the processing gain achieved by averaging the digital signal samples counters the degradation caused by clock jitter. As such, a higher speed A/D converter can be used to directly convert an RF analog signal, thereby reducing the need for frequency conversion stages. In certain embodiments, the data rate or speed is reduced to produce digital output values at a data rate compatible with the digital processing circuitry.

Method and apparatus for analog-to-digital conversion by combining digital sample values

An analog-to-digital converter (ADC) includes a dither signal generator configured to add an analog dither signal to the analog input signal of the ADC prior to digitization (i.e., quantization). The amplitude of the dither signal is selected based upon the power levels of one or more carriers present in the bandwidth for which the ADC is designed to operate. Addition of the dither signal to the input signal in the analog domain reduces quantization noise such as conversion spurs that result from non-linearities in the ADC transfer function.

Carrier-dependent dithering for analog-to-digital conversion

A filter including an enclosure, a dielectric material within the enclosure, at least two microstrip antennas within the enclosure, and at least one frequency selective surface including a metallic pattern. The frequency selective surface is utilized to filter an electromagnetic signal propagated within the enclosure. The geometry of the antennas and the frequency selective surfaces as well as the resonant frequencies of the frequency selective surfaces determine whether the filter is a bandpass, bandstop, notched, or combination filter. If the frequency selective surface is omitted, the combination acts as a delay circuit for delaying the electromagnetic signal, where the time delay is a function of the dielectric constant of the dielectric material.

Filter including a microstrip antenna and a frequency selective surface

A microstrip feeds a patch antenna through a slot in a two part RF ground plane. The dual RF ground planes permit DC control of a varactor positioned over a slot in the ground planes while maintaining a high degree of AC coupling between the two planes. The AC coupling between the two ground planes is increased by increasing the capacitive coupling between the planes using an interlocking finger pattern.

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Malabar, FL, United States of America

Arild T Kolsrud