Abstract: According to one aspect of the present invention, an apparatus is provided to enable weather band radio signals to be received and processed using a digital signal processor (DSP). The DSP can include functionality to implement both frequency modulation (FM) demodulation and weather band data demodulation, i.e., specific area encoding (SAME) demodulation. In one such embodiment, soft decision samples of a SAME message can be combined, and based on a combined result, a hard decision unit can generate a bit value of weather band data.

Abstract: According to one aspect of the present invention, an apparatus is provided to enable weather band radio signals to be received and processed using a digital signal processor (DSP). The DSP can include functionality to implement both frequency modulation (FM) demodulation and weather band data demodulation, i.e., specific area encoding (SAME) demodulation. In one such embodiment, soft decision samples of a SAME message can be combined, and based on a combined result, a hard decision unit can generate a bit value of weather band data.

Abstract: According to one aspect of the present invention, an apparatus is provided to enable weather band radio signals to be received and processed using a digital signal processor (DSP). The DSP can include functionality to implement both frequency modulation (FM) demodulation and weather band data demodulation, i.e., specific area encoding (SAME) demodulation. In one such embodiment, soft decision samples of a SAME message can be combined, and based on a combined result, a hard decision unit can generate a bit value of weather band data.

Abstract: One aspect of the present invention is directed to an apparatus to perform impulse blanking of a received signal at multiple locations of a signal processing path. To effect such impulse blanking, multiple impulse detectors and blankets may be present, in addition to other circuitry. The impulse detectors may operate at different bandwidths, and the impulse blankers may be located at different locations of the signal processing path and may be differently configured.

Abstract: In one embodiment, the present invention includes a digital mixer to receive and digitally mix incoming weather band radio data with a control signal, a digital demodulator to demodulate the data to obtain a demodulated signal, and a digital feedback loop coupled between the demodulator and the digital mixer. The digital feedback loop includes a loop filter to receive the demodulated signal and to generate a filtered output and a fine tune controller to receive the filtered output and a frequency control signal and to generate the control signal based on them. In this way, audible artifacts caused by a frequency step change occurring in an analog front end to which the digital circuitry is coupled can be reduced or removed.

Abstract: In one embodiment, a method for processing radio frequency signals includes estimating an average value of a demodulated signal and a noise signal, both obtained from a radio frequency signal, estimating a noise floor based on the noise signal, generating a blend control signal based on the average values and the noise floor, and blending at least two path signals based on the blend control signal to obtain a blended signal. This blended signal may be output for further processing when multipath noise is detected.

Abstract: In one embodiment, a receiver includes parallel paths for signal channel processing and image channel processing. The paths may include a mixer to receive an intermediate frequency (IF) signal and to downconvert the IF signal to a channel baseband signal, a filter to generate a filtered channel value, a combiner to combine the channel baseband signal with a filtered channel value from the other path to obtain a channel path output, in addition to one or more controllers to generate a step control signal and update a weighting of the filters based at least in part on the step control signal.

Abstract: Embodiments of the present invention relate generally to receivers. A frequency modulated (FM) receiver includes an equalizer control unit coupled to receive at least one FM signal quality indicator and provide a control signal based on the FM signal quality indicator. An adaptive equalizer coupled to receive the control signal from the equalizer control unit and an FM signal and provide a filtered FM signal corresponding to the received FM signal. Coefficients of the adaptive equalizer are reset in response to the control signal. Another embodiment relates to a method for processing a frequency modulated (FM) signal. An FM signal is received. At least one FM signal quality indicator is used to provide a control signal. Based on the control signal, the received FM signal is filtered using one of an adaptive filter and a static filter to provide a filtered FM signal.

Abstract: In one embodiment, the present invention includes a method for receiving data corresponding to a portion of an incoming radio frequency (RF) spectrum, determining a set of estimates including one or more pairs of a channel frequency estimate and a symbol rate estimate from the data via a linear spectrum analysis, and determining a refined set of estimates from the set of estimates via at least one non-linear spectrum analysis.

Abstract: In one embodiment, the present invention includes a digital mixer to receive and digitally mix incoming weather band radio data with a control signal, a digital demodulator to demodulate the data to obtain a demodulated signal, and a digital feedback loop coupled between the demodulator and the digital mixer. The digital feedback loop includes a loop filter to receive the demodulated signal and to generate a filtered output and a fine tune controller to receive the filtered output and a frequency control signal and to generate the control signal based on them. In this way, audible artifacts caused by a frequency step change occurring in an analog front end to which the digital circuitry is coupled can be reduced or removed.

Abstract: According to one aspect of the present invention, an apparatus is provided to enable weather band radio signals to be received and processed using a digital signal processor (DSP). The DSP can include functionality to implement both frequency modulation (FM) demodulation and weather band data demodulation, i.e., specific area encoding (SAME) demodulation. In one such embodiment, soft decision samples of a SAME message can be combined, and based on a combined result, a hard decision unit can generate a bit value of weather band data.

Abstract: One embodiment of the present invention relates to noise control of one or more signals. In one embodiment, impulsive-type noise events, such as multipath noise events or pops, may be detected and suppressed to reduce signal distortion. For example, in one embodiment related to a radio receiver (100), a predictor (436) having an adaptive filter (402) is used in combination with a fast attack slow decay mechanism (434) to provide noise control signals (352, 358) which may then be used to suppress noise events. In one embodiment, the fast attack slow decay mechanism includes applying a wide bandwidth filter at the onset of a noise event to quickly track variations in an error signal and applying a narrow wide bandwidth filter a peak of the noise event is detected in order to smooth variations in the error signal (410). This allows for improved psycho-acoustic perception. In one embodiment, the radio receiver is a mobile radio receiver.

Abstract: An asynchronous sample rate converter including a feedback loop configured to generate a control signal corresponding to an output sample rate that is synchronous with an output clock signal and a normalized time distance value corresponding to a plurality of input samples and an interpolator configured to generate an output sample in response to receiving the control signal using the normalized time distance value and outputs of at least two polyphase filter components that are generated from at least the plurality of input samples is provided.

Abstract: A noise blanker (40, 106) monitors and removes noise from a sampled signal by adaptive filtering (98, 150) the sampled signal to generate trained adaptive filter prediction coefficients. The sampled signal is provided as an output signal when the noise blanker is in a training mode. A noise monitor (34, 154) detects whether noise contained within the sampled signal exceeds a predetermined threshold and provides a control signal in response to the detecting. The noise blanker is placed in a prediction mode for a predetermined amount of time in response to asserting the control signal. A prediction output signal is generated using a plurality of prediction coefficients as an all-pole filter. The prediction output signal has minimal noise content.

Abstract: In one embodiment, the present invention includes a method for receiving data corresponding to a portion of an incoming radio frequency (RF) spectrum, determining a set of estimates including one or more pairs of a channel frequency estimate and a symbol rate estimate from the data via a linear spectrum analysis, and determining a refined set of estimates from the set of estimates via at least one non-linear spectrum analysis.

Abstract: An AM/FM DIF radio has an IF to audio converter that provides an audio signal from an IF signal responsive to a clock signal. During the processing of the IF signal, a spurious signal is intentionally generated. The spurious signal is based on the predetermined offset which is included in the IF signal applied to an A/D converter. The predetermined offset is greater than or equal to half of the AM bandwidth and less than or equal to the system bandwidth. The spurious signal is generated at a frequency proportional to the sum of an imprecision offset and the predetermined offset. A low pass filter removes the spurious signal while preserving the desired portion of the audio signal.

Abstract: A method for stopping on a radio station includes calculating a radio signal quality (205) using a multipath echo indicator and determining if the radio signal quality is greater than a predetermined signal quality threshold (210). A zero crossings indicator of a demodulated signal may be used (225) to reduce a false alarm rate. An apparatus includes an antenna (105), a local oscillator (110) coupled to the antenna, an analog-to-digital converter circuit (115) coupled to the local oscillator, a demodulator circuit (120) coupled to the analog-to-digital converter circuit, a signal strength determining circuit (125) coupled to the analog-to-digital converter circuit, a logarithmic circuit (150) coupled to the signal strength determining circuit, a multipath echo bandpass filter (155) coupled to the logarithmic circuit, and a stop-on-station circuit (145) coupled to the demodulator circuit, the multipath echo bandpass filter, and the logarithmic circuit.

Abstract: A radio receiver (100) has an IF (intermediate frequency) filter (200) for automatically adjusting its intermediate frequency. The filter (200) includes a filter bank (304), an accumulative sub-band formation (322) and an accumulative sub-band power estimator/switch control (324). The filter bank (304) generates sub-bands, each sub-band having a predetermined frequency range. The accumulative sub-band formation (322) selectively sums the sub-bands to provide lowpass filters having incrementally increasing bandwidth. Power estimates of the lowpass filters are used to determine which lowpass filter output is appropriate for adjacent station interference. Also, if there is no adjacent station interference, the IF filter (200) selects the appropriate filter output depending on the signal strength of the desired station.

Abstract: Embodiments of the present invention relate generally to receivers. A frequency modulated (FM) receiver includes an equalizer control unit coupled to receive at least one FM signal quality indicator and provide a control signal based on the FM signal quality indicator. An adaptive equalizer coupled to receive the control signal from the equalizer control unit and an FM signal and provide a filtered FM signal corresponding to the received FM signal. Coefficients of the adaptive equalizer are reset in response to the control signal. Another embodiment relates to a method for processing a frequency modulated (FM) signal. An FM signal is received. At least one FM signal quality indicator is used to provide a control signal. Based on the control signal, the received FM signal is filtered using one of an adaptive filter and a static filter to provide a filtered FM signal.

Abstract: An AM/FM DIF radio has an IF to audio converter that provides an audio signal from an IF signal responsive to a clock signal. During the processing of the IF signal, a spurious signal is intentionally generated. The spurious signal is based on the predetermined offset which is included in the IF signal applied to an A/D converter. The predetermined offset is greater than or equal to half of the AM bandwidth and less than or equal to the system bandwidth. The spurious signal is generated at a frequency proportional to the sum of an imprecision offset and the predetermined offset. A low pass filter removes the spurious signal while preserving the desired portion of the audio signal.