An apparatus and a method for synchronizing a Digital Frequency Shift (DFS) for a signal to be transmitted over a wireless channel are disclosed. For example, the method, by a synchronizer, transmits a DFS trigger to a Digital Front End (DFE) processor and a Local Oscillator (LO) trigger to an LO in a synchronous manner, the method, by the DFE processor, applies a DFS on received data in response to receiving the DFS trigger, the method, by the LO, applies a complementary shift on a carrier signal in response to receiving the LO trigger, the method, by the upconverter, digital-to-analog converts and radio frequency modulates the digital frequency-shifted received data and the complementary-shifted carrier signal. In another example, the method, by the synchronizer, transmits a phase error to a phase error corrector that performs a phase error correction.

The embodiments described herein provide systems and methods for digital correction in low intermediate frequency (IF) receivers. Specifically, the embodiments described herein use digital correction techniques that can correct for signal distortions in low IF receivers caused by I-Q imbalance, including both I-Q magnitude imbalance and I-Q phase imbalance. In general, the embodiments described herein are implemented to at least partially cancel an image of a blocking signal in the complex digital signal. Such a cancellation can be implemented to at least partially cancel an image of blocking signal where that image occurs at or near the intermediate frequency. In one embodiment, a corrector is implemented in a low RF receiver and is configured to receive a complex digital signal that includes an image of a blocking signal. Such a low RF receiver can further include a corrector controller to selectively enable the corrector.

A mixer includes: a VGA (12) configured to amplify one of divided two portions of an input signal at a gain of cos ; a VGA (13) configured to amplify another one of the divided two portions of the input signal at a gain of sin ; an IQ generator (15) configured to input an LO wave, and output an LO wave in phase with the input LO wave and an LO wave having a phase difference of 90 with respect to the input LO wave; a mixer (16) configured to input the signal output from the VGA (12) and the LO wave which is output from the IQ generator (15) , to output an RF signal; a second mixer (17) configured to input the signal from the VGA (13) and the LO wave which is output from the IQ generator, to output an RF signal; and a combiner (18).

IQ mismatch correction for analog chain IQ mismatch impairments is based on a two-filter architecture. In either RX or TX, an IQmc mismatch corrector (digital chain) filters I and Q digital signals, and includes an I-path to receive the I signal, and a Q-path to receive the Q signal, and is configured with two filters: an in-path filter to filter either the I signal or the Q signal received in the same path; and a cross-path filter to filter either the I signal or the Q signal received in the other path. The IQmc mismatch corrector can include: an I-path delay element to provide a delay to the I signal corresponding to a delay through either the in-path filter or the cross-path filter; and a Q-path delay element to provide a delay to the Q signal corresponding to a delay through either the in-path filter or the cross-path filter.

For example, an apparatus may include a Local Oscillator (LO) generator configured to generate a distributed modulated LO signal by modulating an LO signal based on a reset signal; and a plurality of Physical Layer (PHY) chains to receive the distributed modulated LO signal, which is distributed to the plurality of PHY chains by the LO generator, a PHY chain of the plurality of PHY chains including a reset detector configured to detect the reset signal based on the distributed modulated LO signal, and, based on a detection of the reset signal, to reset one or more Radio Frequency (RF) elements of the PHY chain.

A method of providing wireless communications in a wireless network can include wirelessly receiving a chirp spread-spectrum modulated signal at a first gateway device, the chirp spread-spectrum modulated signal being transmitted by a remote client device. The chirp spread-spectrum modulated signal can be demodulated at the first gateway device to provide demodulated data at the first gateway device. The demodulated data can be processed to provide an indication that a decode of a packet including the demodulated data failed. Time adjacent chirps included in the demodulated data can be combined to provide combined data at the first gateway device. A message can be transmitted from the first gateway device to a remote server responsive to an amplitude of the combined data exceeding a threshold value and the indication that the decode of the packet including the demodulated data failed.

A method of providing wireless communications in a wireless network can include wirelessly receiving a chirp spread-spectrum modulated signal at a first gateway device, the chirp spread-spectrum modulated signal being transmitted by a remote client device. The chirp spread-spectrum modulated signal can be demodulated at the first gateway device to provide demodulated data at the first gateway device. The demodulated data can be processed to provide an indication that a decode of a packet including the demodulated data failed. Time adjacent chirps included in the demodulated data can be combined to provide combined data at the first gateway device. A message can be transmitted from the first gateway device to a remote server responsive to an amplitude of the combined data exceeding a threshold value and the indication that the decode of the packet including the demodulated data failed.

A transmitter generates programmable upstream and downstream signal pulses for transmission through a fluid whose flow rate is being measured. A receiver receives the upstream and downstream signal pulses and stores digital representations of the pulses. A multiple pass algorithm such as a time domain windowing function and/or an algorithm that equalizes amplitude operates on the stored digital representations prior to demodulation. A quadrature demodulator generates in-phase and quadrature components of the digital representations and an arctangent function using the in-phase and quadrature components determines angles associated with the upstream and downstream signal pulses. The difference between the upstream and downstream angles, from which a difference in time of flight between the upstream and downstream signal pulses can be derived, is used to determine flow rate.

Certain aspects of the disclosure are directed to in-phase/quadrature (IQ) mismatch detection and correction in radio frequency receivers. According to a specific example, a method of manufacture or use comprises, in a quadrature radio-frequency receiver configured to process signals using I and Q components, providing parameters indicative of IQ mismatches associated with circuitry of the quadrature radio-frequency receiver due to changes in signal gain. The method further includes, while using the quadrature radio-frequency receiver to receive and process a received radio signal, correcting for the IQ mismatches by using the parameters in response to actual signal gain change.

In a communication device and corresponding methods to determine a phase offset imbalance, an input signal (e.g. oscillator signal) is phase shifted to generate a set of phase-shifted values. The set of phased-shifted values and the input signal are mixed to generate a respective set of mixed signals. The phase offset imbalance (e.g. phase error) is calculated based on the set of mixed signals and a gradient value.