Method and apparatus for receive channel noise suppression

A method in a receiver of suppressing noise, comprising the steps of:

• receiving an inbound signal comprising a desirable signal component and an internal noise component;
• splitting the inbound signal into substantially identical first signal and second signals;
• generating a first LO frequency signal and a second LO frequency signal, where the first LO frequency signal and second LO frequency signal differ from one another by an offset in frequency;
• mixing the first signal with the first LO frequency signal to create a first mixed signal, and mixing the second signal with the second LO frequency signal to create a second mixed signal;
• filtering the first mixed signal by a first bandpass filter thereby generating a first filtered signal;
• filtering the second mixed signal by a second bandpass filter thereby generating a second filtered signal, wherein said second filtered signal consists substantially of said internal noise component and said first filtered signal comprises said desirable signal component;
• shifting the phase of the second-filtered signal approximately 180 degrees to create a phase-shifted second filtered signal;
• shifting the phase of the first filtered signal to create a phase-shifted first filtered signal that corrects for offset in frequency;
• and
• combining the phase-shifted first filtered signal and the phase-shifted second filtered signal to create a noise suppressed output signal having said desirable signal component wherein said internal noise component is substantially suppressed.

A noise suppression apparatus for use in a receiver, comprising:

• an input terminal adapted to receive an inbound signal comprising a desirable signal component and an internal noise component;
• a mixer coupled to the input terminal and configured to receive the inbound signal;
• a local oscillator coupled to the mixer and configured to generate a LO frequency signal;
• wherein the mixer is configured to mix the inbound signal with the LO frequency signal to create a mixed signal;
• a channel splitter coupled to the mixer and configured to split the mixed signal into a substantially identical first signal and second signal;
• a first bandpass filter coupled to the channel splitter having a first passband frequency range and configured to generate a first filtered signal;
• a second bandpass filter coupled to the channel splitter having a second passband frequency range and configured to generate a second filtered signal;
• wherein LO frequency signal and said first and second passband frequency ranges are selected such that said first filtered signal comprises said desirable signal component and said second filtered signal consists essentially of said internal noise component;
• a first phase shifting structure coupled to the second band pass filter and configured to shift the phase of the second filtered signal approximately 180 degrees to create a phase-shifted second filtered signal;
• a second phase shifting structure coupled to the first bandpass filter and configured to fine tune the phase of the first filtered signal to create a phase-shifted first filtered signal that corrects for an offset in phase between the first filtered signal and the second filtered signal;
• and
• a combiner coupled to the first bandpass filter and the second bandpass filter and configured to combine the phase-shifted first filtered signal with the phase-shifted second filtered signal to create a noise suppressed output signal having said desirable signal component and wherein said internal noise component is substantially suppressed.

A method in a receiver of suppressing noise, comprising the steps of:

• receiving an inbound signal comprising a desirable signal component and an internal noise component;
• mixing the inbound signal with an LO frequency signal to create a mixed signal;
• splitting the mixed signal into a substantially identical first signal and second signal;
• filtering the first mixed signal by a first bandpass filter thereby generating a first filtered signal;
• filtering the second signal by a second bandpass filter thereby generating a second filtered signal, wherein said second filtered signal consists substantially of said internal noise component and said first filtered signal comprises said desirable signal component;
• shifting the phase of the second filtered signal approximately 180 degrees to create a phase-shifted second filtered signal;
• shifting the phase of the first filtered signal to create a phase-shifted first filtered signal that corrects for an offset in phase between the first filtered signal and the second filtered signal;
• and
• combining the phase-shifted first filtered signal with the phase-shifted second filtered signal to create a noise suppressed output signal having said desirable signal component and wherein said internal noise component is substantially suppressed.