Patent ID: 6256358
Filing Date: 2001-07-03
Classification: H03D

Abstract:
A digital signal processor for a multiband radio receiver that processes audio signals from a radio tuner including a narrowband IF signal from a first broadcast band and a wideband IF signal from a second broadcast band, said digital signal processor comprising:a half-complex mixer block selectably responsive to said narrowband IF signal when said processor is in a narrowband mode or said wideband IF signal when said processor is in a wideband mode to generate a digital complex IF signal at a predetermined IF frequency and at a first sample rate, said complex IF signal including an in-phase component and a quadrature-phase component;a decimator block with dual sections coupled to said half-complex mixer block, each section of said decimator block decimating a respective one of said in-phase component and said quadrature-phase component of said complex IF signal by a predetermined ratio to produce a sample-rate reduced complex IF signal at a second sample rate;a reconfigurable digital filter block with dual sections, each section of said digital filter block having selectable sets of filter coefficients including a first set corresponding to said narrowband mode and a second set corresponding to said wideband mode, said first set of filter coefficients configuring said digital filter block as a decimator to further reduce the sample rate of said sample-rate reduced complex IF signal to a third sample rate when in said narrowband mode, and said second set of filter coefficients configuring said digital filter block as a channel lowpass filter to reject undesired signals from said sample-rate reduced complex IF signal without further sample rate reduction when in said wideband mode; anda programmable processor block receiving outputs from said dual sections of said digital filter block, said programmable processor block including a program memory and a program sequencer, said program memory containing a first executable code block for use in said narrowband mode and a second executable code block for use in said wideband mode, said first executable code block performing a channel filtering and narrowband detection function at said third sample rate, and said second executable code block performing a wideband detection function at said second sample rate.