Apparatus for deriving in-phase and quadrature-phase baseband signals from a communication signal
First Claim
1. An apparatus for deriving in-phase (I) and quadrature-phase (Q) baseband signals from a digitized signal having a sampling rate, the apparatus comprising:
- band pass filter coupled to the digitized signal for band pass filtering the digitized signal to produce a band passed signal;
delay element coupled to the band pass filter for delaying the band passed signal to produce a delayed band passed signal;
decimator means coupled to the band pass filter for decimating the band passed signal and the delayed band passed signal by a predetermined amount to produce, respectively, a decimated signal and a decimated delayed signal; and
low pass filter means coupled to the decimator means for low pass filtering the decimated signal and the decimated delayed signal to produce, respectively, the I and Q baseband signals.
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Abstract
In-phase (I) and quadrature-phase (Q) baseband signals (312, 314) are derived from a digitized signal (318) having a sampling rate. The digitized signal is band pass filtered (604) to produce a band passed signal (320), and the band passed signal is delayed (606) to produce a delayed band passed signal (322). The band passed signal and the delayed band passed signal are decimated (608) by a predetermined amount to produce, respectively, a decimated signal (328) and a decimated delayed signal (330). The decimated signal and the decimated delayed signal are low pass filtered (610) to produce, respectively, the I and Q baseband signals.
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Citations
12 Claims
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1. An apparatus for deriving in-phase (I) and quadrature-phase (Q) baseband signals from a digitized signal having a sampling rate, the apparatus comprising:
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band pass filter coupled to the digitized signal for band pass filtering the digitized signal to produce a band passed signal; delay element coupled to the band pass filter for delaying the band passed signal to produce a delayed band passed signal; decimator means coupled to the band pass filter for decimating the band passed signal and the delayed band passed signal by a predetermined amount to produce, respectively, a decimated signal and a decimated delayed signal; and low pass filter means coupled to the decimator means for low pass filtering the decimated signal and the decimated delayed signal to produce, respectively, the I and Q baseband signals. - View Dependent Claims (2, 3, 4)
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5. A baseband derivation circuit for deriving in-phase (I) and quadrature-phase (Q) baseband signals from an analog signal, the baseband derivation circuit comprising:
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a sigma-delta analog-to-digital converter coupled to the analog signal for producing a digitized signal having a sampling rate; a band pass filter coupled to the sigma-delta analog-to-digital converter for band pass filtering the digitized signal to produce a band passed signal; a delay element coupled to the band pass filter for delaying the band passed signal to produce a delayed band passed signal; first and second decimators coupled, respectively, to the band pass filter and the delay element for decimating the band passed signal and the delayed band passed signal by a predetermined amount to produce, respectively, a decimated signal and a decimated delayed signal; and first and second low pass filters coupled, respectively, to the first and second decimators for low pass filtering the decimated signal and the decimated delayed signal to produce, respectively, the I and Q baseband signals. - View Dependent Claims (6, 7, 8)
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9. A communication receiver, comprising:
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an antenna for intercepting a radio signal comprising information; a receiver element coupled to the antenna for down-converting the radio signal to derive an analog signal and for demodulating the analog signal; a processing system coupled to the receiver element for processing the information; a user interface coupled to the processing system for conveying the information to a user; and user controls coupled to the processing system for providing control of the communication receiver by the user, wherein the receiver element comprises a baseband derivation circuit for deriving in-phase (I) and quadrature-phase (Q) baseband signals from the analog signal, the baseband derivation circuit comprising; a sigma-delta analog-to-digital converter coupled to the analog signal for producing a digitized signal having a sampling rate; a band pass filter coupled to the sigma-delta analog-to-digital converter for band pass filtering the digitized signal to produce a band passed signal; a delay element coupled to the band pass filter for delaying the band passed signal to produce a delayed band passed signal; first and second decimators coupled, respectively, to the band pass filter and the delay element for decimating the band passed signal and the delayed band passed signal by a predetermined amount to produce, respectively, a decimated signal and a decimated delayed signal; and first and second low pass filters coupled, respectively, to the first and second decimators for low pass filtering the decimated signal and the decimated delayed signal to produce, respectively, the I and Q baseband signals. - View Dependent Claims (10, 11, 12)
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Specification