Described herein are systems and methods that allow for correcting a residual frequency offset in the GHz frequency range by using low-complexity analog circuit implementations of a broad-band frequency detector that comprises two analog polyphase filters in a dual configuration. Each filter comprises an RC network of cross-coupled capacitors that facilitate filters with opposite passbands and opposite stop-bands. In various embodiments, the outputs of the two filters are combined to obtain power metrics that when subtracted from each other, deliver a measure of the imbalance between the positive and negative halves of a frequency spectrum. Since the measure is substantially proportional to a frequency offset within a linear range spanning 5 GHz or more, the polyphase filters may be used in a broad-band frequency detector that, based on the measure, adjusts the frequency offset.

Described herein are systems and methods that allow for correcting a residual frequency offset in the GHz frequency range by using low-complexity analog circuit implementations of a broad-band frequency detector that comprises two analog polyphase filters in a dual configuration. Each filter comprises an RC network of cross-coupled capacitors that facilitate filters with opposite passbands and opposite stop-bands. In various embodiments, the outputs of the two filters are combined to obtain power metrics that when subtracted from each other, deliver a measure of the imbalance between the positive and negative halves of a frequency spectrum. Since the measure is substantially proportional to a frequency offset within a linear range spanning 5 GHz or more, the polyphase filters may be used in a broad-band frequency detector that, based on the measure, adjusts the frequency offset.

Described herein are systems and methods that allow for correcting a residual frequency offset in the GHz frequency range by using low-complexity analog circuit implementations of a broad-band frequency detector that comprises two analog polyphase filters in a dual configuration. Each filter comprises an RC network of cross-coupled capacitors that facilitate filters with opposite passbands and opposite stop-bands. In various embodiments, the outputs of the two filters are combined to obtain power metrics that when subtracted from each other, deliver a measure of the imbalance between the positive and negative halves of a frequency spectrum. Since the measure is substantially proportional to a frequency offset within a linear range spanning 5 GHz or more, the polyphase filters may be used in a broad-band frequency detector that, based on the measure, adjusts the frequency offset.

The present disclosure teaches methods for digitally transmitting data. An example method may include: receiving a modulated signal containing at least one useful signal or noise or interference signals; repeatedly estimating at least one parameter of the received signal relevant to the demodulation of the useful signal; monitoring changes in the repeatedly estimated parameters; and detecting a useful signal based at least in part on whether one or more changes in the repeatedly estimated parameters satisfy at least one particular, predefined condition.