BACKGROUND

Field of the Invention

The invention relates to communications technology and more particularly to communication using radio technology.

Description of the Related Art

Operation of a radio receiver in a noisy environment introduces noise into the received signal. In an exemplary radio application, a desired modulated radio frequency signal is corrupted by a substantial interfering signal (e.g., a constant tone or a modulated signal in the target frequency band). For example, a constant tone may be introduced as a result of operating an electric motor proximate to the radio receiver or a modulated interfering signal may be introduced into the received signal by operating the radio receiver near a radio using a different communications protocol. A substantial interfering signal in the target frequency band may increase the dynamic range of the received signal beyond the dynamic range needed to represent the desired information in the received signal. Accordingly, transmission of the received signal having that increased dynamic range, e.g., to an external demodulator, may require a transceiver to operate at a higher data rate, use a faster clock signal, or communicate more information than needed to recover the desired information. Accordingly, techniques for reducing the dynamic range of a received radio frequency signal are desired.

SUMMARY OF EMBODIMENTS OF THE INVENTION

In at least one embodiment of the invention, a method for reducing a dynamic range of a received radio frequency signal includes receiving digital IQ signals corresponding to an in-phase component of the received radio frequency signal and a quadrature component of the received radio frequency signal. The method includes demodulating the digital IQ signals to generate an instantaneous frequency signal. The method includes selecting a center frequency of a selectable filter according to whether an interfering signal is detected in a target frequency band of the received radio frequency signal. The center frequency is selected from a predetermined frequency and an estimated center frequency determined using the instantaneous frequency signal. The method includes filtering the digital IQ signals using the selectable filter configured using the center frequency to generate output digital IQ signals.

In at least one embodiment, a receiver includes a receiver signal path configured to provide digital IQ signals corresponding to an in-phase component of a received radio frequency signal and a quadrature component of the received radio frequency signal. The receiver includes a demodulator configured to provide an instantaneous frequency signal based on the digital IQ signals. The receiver includes a selectable filter configured to provide output digital IQ signals based on the digital IQ signals and a center frequency. The receiver includes a select circuit configured to select the center frequency of the selectable filter according to whether an interfering signal is detected in a target frequency band of the received radio frequency signal. The center frequency is selected from a predetermined frequency and an estimated center frequency determined using the instantaneous frequency signal.

In at least one embodiment, a program product is encoded in a tangible machine-readable medium. The program product includes instructions executable by a processor to: receive digital IQ signals corresponding to an in-phase component of a received radio frequency signal and a quadrature component of the received radio frequency signal; demodulate the digital IQ signals to generate an instantaneous frequency signal; select a center frequency of a selectable filter according to whether an interfering signal is detected in a target frequency band of the received radio frequency signal, the center frequency being selected from a predetermined frequency and an estimated center frequency determined using the instantaneous frequency signal; and filter the digital IQ signals using the selectable filter to generate an output digital signal.

