A system and a method that enable two or more dispersed platforms to simultaneously use respective frequency-modulated continuous-wave radar systems in a typical radar application such as synthetic-aperture radar for terrain mapping, moving-target indicator radar to track targets on the ground and air-to-air tracking of other aircraft. The systems use the same RF spectrum in their operation and also communicate through their respective radar systems while simultaneously reducing their interplatform interference through the use of both filters and coded waveforms.

By changing frequencies of an oscillation signal and an injection signal, a frequency-converted self-injection-locked radar has an oscillation frequency different to a frequency of a transmitted signal from a transceiver antenna element such that the frequency-converted self-injection-locked radar with high sensitivity and penetration or with high sensitivity and low cost is achieved.

By changing frequencies of an oscillation signal and an injection signal, a frequency-converted self-injection-locked radar has an oscillation frequency different to a frequency of a transmitted signal from a transceiver antenna element such that the frequency-converted self-injection-locked radar with high sensitivity and penetration or with high sensitivity d low cost is achieved.

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.

Wideband polar receivers and method of operation are described. A phase-modulated input signal is received at a polar receiver that includes an injection-locked oscillator. The injection-locked oscillator includes a plurality of injection points. Based on the frequency of the input signal, a particular Nth harmonic is selected, and the input signal is injected at the set of injection points corresponding to the selected Nth harmonic. The injection-locked oscillator generates an oscillator output signal, and the phase of the input signal is determined from the phase of the oscillator output signal. In some embodiments, the oscillator output signal is frequency-multiplied by N, mixed with the input signal, and filtered for use in amplitude detection. The input signal is decoded based on the phase and amplitude information.

A lock-in amplifier includes a clock signal generator configured to generate a first demodulation clock signal and a second demodulation clock signal having a phase difference of 90 degrees and a same demodulation frequency; and a detector configured to, based on an input signal, the first demodulation clock signal, and the second demodulation clock signal, provide an offset voltage corresponding to an offset of the lock-in amplifier in a first operation mode, and provide a first output voltage and a second output voltage, each of which correspond to a demodulation frequency component of the input signal in a second operation mode.

Aspects of this disclosure relate to a very low intermediate frequency (VLIF) receiver with multi-decade contiguous radio frequency (RF) band coverage. Non-quadrature local oscillator (LO) signals drive mixers. The non-quadrature signals can be generated from low noise digital dividers having non-traditional division ratios. The non-traditional division ratios can be prime number ratios such as 5 and 7. The systematic non-quadrature nature of the LO/mixer can be subsequently corrected by a deterministic I-Q coupling network prior to complex signal processing.

An apparatus and a method using no switching elements for multiplexing and reading arrays of sensors whose electrical resistance is modulated by the signals to be measured are proposed. Sensor elements are arranged in groups and columns where each column is fed with a continuous voltage waveform of different amplitude, frequency and phase characteristics which then produce current signals that are modulated by the variable resistance signals to be measured. Modulated currents are summed row-wise and collected at the read-out circuits, either by applying a constant voltage to each row of the array or by connecting a capacitor and converting these current summations into output voltage signals. The read-out circuits de-multiplex each individual sensor signal to be measured by lock-in demodulation according to the frequencies and phases employed for the stimulation of each column.

An IF filter band-limits an intermediate frequency signal outputted from a mixer. An AFC unit controls the oscillation frequency of a PLL so that the frequency of the intermediate frequency signal is a predetermined frequency. When the AFC unit controls the oscillation frequency of the PLL, a band control unit controls the passing characteristic of the IF filter to the passing characteristic of a wide band, and after the completion of the control, controls the passing characteristic of the IF filter to the passing characteristic of a narrow band. A frequency correction unit refers to a filter information storage unit, and corrects the oscillation frequency controlled by the AFC unit according to the difference between the center frequency of the passband of the passing characteristic of the wide band and the center frequency of the passband of the passing characteristic of the narrow band.

A measuring device in which a non-electrical variable is converted into an electrical measurement signal via an electrical alternating current having a frequency, wherein the measurement signal contains a signal portion dependent on the non-electrical variable and is double the frequency, and a fault signal portion dependent on the alternating current and is at the frequency, where the measurement signal is pre-processed and digitized to generate a digital signal that is detected and processed to generate a measured value proportional to the non-electrical variable and to generate a fault signal value, wherein the fault signal value is utilized to normalize the measured value that is normalized in a normalizing stage, by forming the quotient using the square of the fault signal value, and is output as a normalized measured value.