Method and apparatus for extracting the quadrature component of a complex signal from the in-phase component after baseband digitizing using a complex transform
AssigneeMotorola Solutions, Inc.
InventorsCharles R. Ruelke, Yadunandana M. Rao
Life of this patent
Estimating the term…
Abstract
A method and apparatus for a receiver system in a receiver that includes at least two front end branches, each branch having its own intermediate frequency (IF) mixer to shift a received signal to an IF. When receiving multiple independent signals, the signals are digitized and the receiver performs a digital complex transform on each signal to obtain the corresponding quadrature component. When receiving a single signal the signal is routed to two mixers that are 90 degrees out of phase to obtain the quadrature signal components in the analog section of the receiver.
Claims19
A receiver system capable of operating as a single watch receiver or a multi watch receiver, the receiver comprising:
- a controller that generates a receiver configuration control signal to configure the receiver to operate in a single watch mode or a multi watch mode;
- a receiver processing block to process one or more received signals based on the receiver configuration control signal, the receiver processing block comprising at least one intermediate frequency (IF) amplifier to optimize SNR of at least one received signal, a first mixer, a second mixer, a local oscillator connected to the first mixer, a first switch that selectively connects the output of the IF amplifier to the second mixer, and a second switch that selectively connects the second mixer to the local oscillator through a 90 degree phase shift,
- wherein in the single watch mode the first switch is configured to connect the IF amplifier to the second mixer and the second switch is configured to connect the second mixer to the local oscillator through the 90 degree phase shift to generate in-phase and quadrature-phase (IQ) constituent pair of the at least one received signal,
- further wherein in the multi-watch mode, the first switch is configured to disconnect the IF amplifier to the second mixer to generate at least one band pass intermediate frequency (BP-IF) signal from the at least one received signal;
- an analog to digital converter that digitizes the IQ constituent pair and the BP-IF signals generated by the receiver processing block to generate digitized IQ signal pair or digitized BP-IF signals;
- and
- a digital complex transform block which is enabled in the multi-watch mode and disabled in the single-watch mode and generates a constituent pair of in-phase (I) and quadrature-phase (Q) components from the digitized BP-IF signal.
A method of operating a receiver system including a receiver processing block having an intermediate frequency (IF) amplifier, first and second mixers, and a local oscillator connected to the first mixer, comprising:
- determining whether a received signal is to be processed to generate an in-phase/quadrature-phase (IQ) signal or a bandpass IF (BP-IF) signal by the receiver system;
- configuring a first switch to connect the IF amplifier to the second mixer when the receiver system is to process the received signal to generate the IQ signal, and to disconnect the IF amplifier from the second mixer when the received signal is to be processed to generate a BP-IF signal;
- configuring a second switch to connect the second mixer to the oscillator through a 90 degree phase shift when the receiver system is to process the received signal to generate the IQ signal;
- digitizing the IQ or BP-IF signal to produce either a digitized IQ signal pair or a digitized BP-IF signal;
- and
- applying a digital complex transform to the digitized BP-IF signal when the received signal is to be processed to generate the BP-IF signal, wherein the complex transform produces a digitized IQ signal pair from the digitized BP-IF signal.
A method for operating a receiver system, comprising:
- determining a mode in which to operate the receiver system, where the mode is either a dual watch mode or a single watch mode;
- configuring a set of switches, responsive to determining the mode, to route signals in the receiver system, wherein in the dual watch mode the switches are configured to route signals through each of at least two analog front end branches to a digital section, and wherein in the single watch mode the switches are configured to route a signal received at a first analog front end branch through mixers of both the first analog front end branch and a second analog front end branch and connect a common local oscillator to a mixer in the first analog front end branch and through 90 degree phase shifter to a mixer in the second analog front end branch to produce analog in-phase and quadrature signals;
- and
- selectively enabling a complex transform block in the digital section, wherein the complex transform is enabled in the dual watch mode to produce a corresponding quadrature signal component for each signal received, and wherein the complex transform is disabled in the single watch mode.
Dependencies are inferred from the claim text.