Abstract: A radio receiver (100) has an equalizer (500) that operates in the time domain to remove residual interference that is not removed by an IF filter (200) operating in the frequency domain that is caused by an adjacent interfering FM station. The equalizer (500) includes a modified constant modulus algorithm (CMA) to generate a tap update signal from the output of the equalizer (500). The equalizer (500) uses the modified CMA to reduce an amplitude fluctuation of the received signal caused by the adjacent interfering station. The CMA is modified to use an infinite impulse response (IIR) filter (540) to generate the tap update. The IIR filter (540) also speeds up a convergence of the modified CMA to provide better performance.

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 demodulator (20) extracts a digital sub-carrier signal from a modulated signal and provides the sub-carrier signal in clock and data format. Demodulation occurs with two mixing stages (32, 40, 42) and at sampling frequencies that are independent from the frequency of transmission of the modulated signal. Matched filters (44, 46) try to match the received sub-carrier signal with a predefined bi-phase pulse shape. Phase correction is applied at a low sampling frequency. After phase correction, digital interpolation is used to re-sample the sub-carrier signal.

Abstract: Embodiments of the present invention relate generally to receivers. One embodiment relates to a digital FM receiver having multiple sensors (e.g. antennas). In one embodiment, the digital receiver includes a baseband unit having a channel processing unit. In one embodiment, the channel processing unit is capable of calculating or estimating a phase difference between the incoming signals prior to combining them. One embodiment uses phase estimation method for diversity combining the signals while another embodiment utlizes a hybrid phase lock loop method. Also, some embodiments of the present invention provide for echo-cancelling after diversity combining. An alternate embodiment of the channel processing unit utilizes a space-time unit to diversity combine and provide echo cancelling for the incoming signals.

Abstract: A radio receiver (100) has an equalizer (500) that operates in the time domain to remove residual interference that is not removed by an IF filter (200) operating in the frequency domain that is caused by an adjacent interfering FM station. The equalizer (500) includes a modified constant modulus algorithm (CMA) to generate a tap update signal from the output of the equalizer (500). The equalizer (500) uses the modified CMA to reduce an amplitude fluctuation of the received signal caused by the adjacent interfering station. The CMA is modified to use an infinite impulse response (IIR) filter (540) to generate the tap update. The IIR filter (540) also speeds up a convergence of the modified CMA to provide better performance.

Abstract: Embodiments of the present invention relate generally to receivers. One embodiment relates to a digital FM receiver having multiple sensors (e.g. antennas). In one embodiment, the digital receiver includes a baseband unit having a channel processing unit. In one embodiment, the channel processing unit is capable of calculating or estimating a phase difference between the incoming signals prior to combining them. One embodiment uses phase estimation method for diversity combining the signals while another embodiment utlizes a hybrid phase lock loop method. Also, some embodiments of the present invention provide for echo-cancelling after diversity combining. An alternate embodiment of the channel processing unit utilizes a space-time unit to diversity combine and provide echo cancelling for the incoming signals.

Abstract: Embodiments of the present invention relate generally to receivers. One embodiment relates to a digital FM receiver having multiple sensors (e.g. antennas). In one embodiment, the digital receiver includes a baseband unit having a channel processing unit. In one embodiment, the channel processing unit is capable of calculating or estimating a phase difference between the incoming signals prior to combining them. One embodiment uses phase estimation method for diversity combining the signals while another embodiment utlizes a hybrid phase lock loop method. Also, some embodiments of the present invention provide for echo-cancelling after diversity combining. An alternate embodiment of the channel processing unit utilizes a space-time unit to diversity combine and provide echo cancelling for the incoming signals.

Abstract: A demodulator (20) extracts a digital sub-carrier signal from a modulated signal and provides the sub-carrier signal in clock and data format. Demodulation occurs with two mixing stages (32, 40, 42) and at sampling frequencies that are independent from the frequency of transmission of the modulated signal. Matched filters (44, 46) try to match the received sub-carrier signal with a predefined bi-phase pulse shape. Phase correction is applied at a low sampling frequency. After phase correction, digital interpolation is used to re-sample the sub-carrier signal.