39 results about "Goertzel algorithm" patented technology

A method and system for stabilizing and demodulating an interferometer at quadrature are described. In response to receipt of a signal indicative of optical power of the interferometer, an interferometer control system determines an optical path length correction required to stabilize the interferometer at quadrature utilizing signal amplitudes appearing at multiple harmonics of the signal. In a particularly preferred embodiment, the signal amplitudes are calculated utilizing the Goertzel algorithm, a computationally efficient discrete Fourier transform. The interferometer control system then outputs an error signal indicative of the optical path length correction. In a preferred embodiment, the error signal forms the DC component of a composite stabilization signal, whose AC component is the reference modulation signal utilized to excite a transducer to modulate the optical path length of the interferometer. With the interferometer stabilized at quadrature, the interferometer control system determines a first signal amplitude of a particular harmonic without target oscillation and a second signal amplitude of the same harmonic with target oscillation. Based upon the relative magnitudes of the first and second signal amplitudes, the interferometer control system determines a solution set for the displacement amplitude of the interferometer target. Any ambiguity in the displacement amplitude can then be eliminated utilizing additional information gained from the signal amplitude present at a harmonic of a target oscillation frequency.

A method to determine and / or monitor at least one process variable of a medium with at least one vibration-capable unit. The vibration-capable unit is excited to mechanical vibrations by means of an electrical excitation signal of an adjustable frequency; wherein the mechanical vibrations are transduced into a received electrical signal, which is characterized at least by a frequency and / or a phase and / or an amplitude. The excitation signal is generated based on the received signal; wherein the voltage values of the received signal are sampled at specified predetermined points in time, starting from the excitation signal. The real part and the imaginary part of the received signal are determined from the sampled voltage values of the received signal by means of a Goertzel algorithm; wherein at least one Goertzel coefficient-in particular the number of the sample values and / or an operating frequency and / or a sample frequency-is provided for performing the Goertzel algorithm. At least the current phase and / or the current amplitude of the received signal are calculated from the real part and the imaginary part of the received signal; wherein the frequency of the excitation signal is adjusted such that a predeterminable phase shift is present between the excitation signal and the received signal; and wherein the at least one process variable is determined.

An acoustic transducer and audio system are checked for operability continuously during operation without interfering with their operation. An inaudible test signal is added on top of a normal audio signal of an electronic device. A mix of the test signal and the normal audio signal is converted to a digital signal which is processed by a type of Fourier transformation, e.g. the Goertzel algorithm, to derive the magnitude of the digital signal at the test signal frequency. The derived magnitude is used to gain knowledge about the functionality of the acoustic transducer and its electrical connection to the electric device, as well as a common audio path.

Exemplary embodiments relates to a demodulator for frequency-shift keyed signals by using the Goertzel algorithm according to the general recursive calculating rule, wherecre=2*cos⁡(2*π*fgfs)with the sampling frequency fs and the specified frequency fg. To reduce the mathematical complexity in feed-power-limited devices, it is proposed that the sampling frequency fs is an integral multiple of the frequency fg of a specified discrete spectral component.

The invention discloses a voice squelch method in a civil aviation VHF anti-jamming transceiver. Firstly, the carrier frequency estimation method based on the Goertzel algorithm is used to judge whether there is a signal or whether the quality is good or bad; The voice detection method distinguishes whether there is a voice signal in the signal; secondly, in conjunction with the AM modulation degree judged in real time by the system, the audio squelch threshold is adaptively adjusted to realize the automatic on-off of the demodulated output voice; the method proposed by the present invention can be used in During normal voice communication, there will no longer be intermittent and some special noises that cannot be turned off, which effectively solves the problem of voice communication quality caused by squelch, and improves the output voice quality level of civil aviation VHF anti-jamming transceivers.

The invention discloses an underwater acoustic communication node wake-up signal detection method based on a frame synchronization signal. According to an existing method, due to the influence of impulse noise and specific environmental noise, the reliability of a detection result is not high, and the computational complexity of a frequency detection and cross-correlation detection related methodin the long-time underwater detection process is high. The method comprises the following steps: firstly, constructing a corresponding MT signal for each node in a communication network, setting two equal-length sliding windows at a receiving end to realize preliminary energy provider detection, and then performing MT frequency confirmation on the signal detected by the preliminary energy providerby using a Goertzel algorithm to realize reliable signal arrival detection. The method is suitable for an underwater communication network with a plurality of communication nodes, accurate awakeningof a target node is realized through an MT signal, the calculation complexity is low, and the energy consumption of long-time signal detection of the underwater communication network node in a dormantstate can be reduced.

The application discloses a DTMF signal detection device, which includes a sequentially connected total energy threshold judgment unit, a Goertzel algorithm DFT amplitude calculation unit, a DFT amplitude basic criterion unit, a frequency-divided FFT energy calculation unit, and a frequency-divided FFT energy enhancement judgment unit. Data unit, DTMF dual-tone frequency retrieval unit. The application also discloses a DTMF signal detection method. The present application improves the accuracy and stability of DTMF signal detection in a complex environment, that is, under interference conditions, and reduces the probability of false alarms through the double judgment mode of DFT operation and judgment and FFT operation and judgment.

Disclosed herein is a method for automatic gain control based on signal spectrum sensing. Spectral sensing techniques may be employed to detect the presence or absence of interference and also determine a frequency location of the interference and power level estimates of a desired signal. The method includes running an algorithm to measure the energy periodically to track the changes as blockers that were not prominent while experiencing deep fade and those that will affect performance when it is out of the deep fade. The method enables predicting a level of degradation for various front-end settings and enables selection of an optimum setting. In an embodiment, the spectral sensing may be performed either in analog domain using narrowband tunable filters. In an embodiment, the spectral sensing may be performed digitally using Fast fourier transform (FFT), Goertzel algorithm, or power detection techniques.

The invention relates to a pseudo passive power grid impendence recognition system and a method based on a Goertzel algorithm. The system comprises a grid-connected inverter, a sampling module, a control module and a PWM driving module, wherein the grid-connected inverter outputs a current set value into a power grid, the sampling module can sample lineside voltage and current through a voltage sensor and a current sensor, the control module can utilize the Goertzel algorithm to extract harmonic component signals of the sampled lineside voltage and current; finally, the harmonic component signals are utilized to calculate the power grid impendence. The pseudo passive detection method comprises the steps of monitoring power grid impendence and injecting harmonic wave into a power grid to measure power grid impendence when larger change happens. The method has the advantages of higher accuracy and smaller system disturbance. The Goertzel algorithm can effectively reduce a controller calculation amount and storage space and further reduces code complexity. In the occasions when only several frequency points need to be analyzed, the Goertzel algorithm has a higher efficiency than FFT.