Correlation Time Delay Estimation Research Articles

A Sound Source Localization Method Based on Frequency Divider and Time Difference of Arrival

In recent years, sound source localization, as a passive localization technique with higher safety and convenience compared with other localization techniques such as active emission of electromagnetic waves, has received more and more attention in academia. This paper researches and improves the far-field sound source localization algorithm based on the generalized cross-correlation method (GCC) Time Difference of Arrival (TDOA) estimation algorithm and completes the design and implementation of the microphone array sound source localization system. This paper adds a frequency divider to the traditional generalized correlation time delay estimation algorithm for pre-processing, sampling, and localization of sound source acoustic waves and adopts a low-cost microphone array deployment scheme as far as possible to improve the flexibility and practicality of the localization system; at the same time, the “Minimum Sphere Method” is used at the back end of the algorithm to classify the localization coordinates at different frequencies and, finally, output reasonable sound source coordinates. In the back-end of the algorithm, the “Minimum Sphere Method” is used to classify the localization coordinates at different frequencies and, finally, output the reasonable sound source coordinates. The experimental results show that the sound source localization system designed in this paper has good performance in terms of localization accuracy and cost-effectiveness and overcomes the failure of the generalized mutual correlation algorithm in the original application of high noise environment and multi-source environment localization.

A sound source localization method based on improved second correlation time delay estimation

The sound source localization (SSL) system based on the microphone array has important applications in audio and video conference, security monitoring and intelligent cockpit. However, the SSL method based on time difference of arrival is susceptible to ambient noise. Therefore, an improved second correlation delay estimation algorithm is proposed in this paper. The pure source signal is obtained by wavelet denoising, and then the time delay is calculated by the second correlation time delay estimation algorithm with the weighting functions of the smoothed coherence transform and the Roth processor. The position of the sound target is calculated from the time delay. Aiming at the moving target, an extended Kalman filter is introduced to track the moving trajectory of the sound source. The static and moving SSL simulations are conducted and the results of the proposed algorithm are compared with those of the single-weighted quadratic correlation (SQC) algorithm and the high-power quadratic correlation algorithm. The static sound source positioning errors of the proposed algorithm under −10 dB SNR are respectively 3.97 m and 5.86 m smaller than those of the HQC algorithm and the SQC algorithm. The moving SSL trajectory based on the proposed algorithm is still closest to the real track under −10 dB SNR. This indicates that the proposed algorithm has high precision and strong robustness for sound source location in the low signal-to-noise ratio (SNR) environment. In the experiment, the proposed algorithm can accurately calculate the direction of arrival (DOA) of static sound source and stably track DOA of moving sound source. This is consistent with the simulation results, which further verifies the effectiveness and practicability of the algorithm. This novel algorithm with high time delay estimation accuracy is of great significance for SSL in low SNR environment.

Wind Speed and Direction Measurement Based on Three Mutually Transmitting Ultrasonic Sensors

The existing ultrasonic anemometer is influenced by the ambient temperature and humidity, shadow effect, and has weak suppression ability for fixed frequency interference, which directly affects the measurement accuracy of the ultrasonic anemometer. In this letter, we propose a three mutually transmitting ultrasonic sensors wind measurement method, which uses a three mutually transmitting ultrasonic sensors array structure combined with the cyclic correlation time delay estimation algorithm for ultrasonic transmission time estimation, and then obtains wind speed and direction values based on the relationship between ultrasonic transmission time and wind vector. The proposed method can effectively reduce the effects of temperature, humidity and shadowing effects on wind vector measurements, suppress interference at different frequencies, and reduce the computational complexity of the time delay estimation algorithm. Finally, we perform simulation experiments to verify the superiority of the proposed algorithm. At the same time, the validity of the proposed method is verified by actual measurement experiment of the three mutually transmitting ultrasonic wind measurement system built. The relative error of wind speed measurement is 3% and the error of wind direction measurement is 3° in the actual measurement environment.

A Method to Improve the Performance of Active Noise Control System Based on Time Delay Estimation

Noise control is a research topic that has been widely concerned for in recent years. When a noise space has a certain volume and/or with complex channel, the method of active noise control (ANC) can be used to reduce or eliminate noise interference. The main channel delay in the active noise control system has an important impact on the performance of the ANC system, however, the traditional method, such as filtered-x least mean square algorithm (FxLMS), lacks the estimation of the main channel delay. This results that the system output cannot be accurately synchronized. Especially in the case of time-varying delay, the effect is less desirable. In this paper, the correlation time delay estimation is combined with FxLMS. A method to improve the performance of active noise control system (CTDE-FxLMS) is proposed based on time delay estimation. In CTDE-FxLMS method, the correlation time delay estimation is used to calculate the main channel delay, and the frequency response of the main channel is calculated by FxLMS. CTDE-FxLMS method improves the synchronization accuracy between the system output and the original noise in the time domain and the frequency domain. The computer simulation results show that the CTDE-FxLMS method has better noise reduction effect than the FxLMS method both the conditions of fixed delay and time-varying delay.

The Performance Correlation Hilbert Time-Delay Estimation for Passive Detection

Passive time difference detection method is distance, high speed and good concealment which has broad military application prospects. One of the key technologies for passive detection is to extract the time lag through effective signal processing. Relevant method is the most basic method to estimate the time difference and is the basic theory of all correlative time-delay estimation algorithms. The method is simple. But good results rely on the spectrum characteristics of signal and noise is ideal. Time delay estimation based on Hilbert transform is the expansion of the generalized correlation time-delay estimation method which changes the correlation function from accidentally symmetry into odd symmetry. Detecting correlation peak is converted into zero crossing detection. The method sharps the main peak value point and improved the precision of time delay estimation which gets better time-delay estimation performance in the narrowband signal.

Laser time-of-flight measurement based on time-delay estimation and fitting correction

We describe a method based on multichannel time-delay estimation with linear fitting correction for laser time-of-flight (TOF) measurement. The laser TOF measurement system is constructed with a laser source, a stop receiver channel, a reference receiver multichannel, an analog to digital converter (ADC) sampling unit, and a digital signal processing unit. Limited by the sampling rate, the precision of laser TOF measurement is restricted no more than the ADC sampling period in conventional methods. As this problem is considered, multichannel correlation time-delay estimation with linear fitting correction is devised. It is shown that the measuring precision is better than 2 ns with multichannel time-delay estimation and not influenced by signal-to-noise ratio. The experimental results demonstrate that the proposed method is effective and stable.

Lightning VHF radiation location system based on short-baseline TDOA technique — Validation in rocket-triggered lightning

A lightning VHF radiation location system based on short-baseline time-difference of arrival (TDOA) technology is newly developed. Based on the orthogonal 10m-baseline antenna array with four identical broadband flat plane antennas, this system receives the lightning broadband VHF radiation signals and calculates TDOA between antennas in order to determine the location of lightning radiation sources in two dimensions (elevation and azimuth). To reduce noise and improve estimation accuracy of time delay, a general correlation time delay estimation algorithm based on direct correlation method and wavelet transform is proposed. Moreover, parabolic interpolation algorithm is used in the fractional delay estimation to improve the time resolution of the positioning system. In this paper, a rocket-triggered lightning discharge and a cloud lightning discharge are analyzed respectively, combining with simultaneous observations of high-speed camera and fast/slow electric field changes. The results indicate that the TDOA location system could effectively map the lightning radiation sources in 2 dimensions and are in a good agreement with the high-speed video camera images.

Leak Detection and Location Using Generalized Correlation Time Delay Estimation Algorithm

The generation of leak along the pipeline carrying crude oils and liquid fuels results enormous financial loss to the industry and also effects the environment and public health. Therefore, the leak detection and localization problem has always been a major concern for the corporation. Pipeline detection and location system plays a key role in many industrial processes and activities. In this paper, a leak detection scheme based on generalized correlation time delay estimation algorithm is proposed to solve the problem of leak detection. By estimating the time delay of the two received signals, the system can provide the information of the leak. The experimental results indicate the effectiveness of this approach.

Interferometric synthetic aperture processing: a comparison of sonar and radar

Interferometric aperture synthesis is an inverse problem that attempts to form an elevation map of the earth (in the case of radar) or a bathymetric map of the seafloor (in the case of sonar). In both cases, a pair of (nominally) vertically displaced transducers is configured as an interferometer. After aperture synthesis is performed to produce a pair of images, the height of each resolvable scatterer can be estimated using time delay estimation between the image pairs and knowledge of the system geometry. While interferometric synthetic aperture sonar (InSAS) seems like an obvious extension of the methods of interferometric synthetic aperture radar (InSAR), the height estimation algorithms are surprisingly different. In this paper we start with the principle of generalised correlation for optimal time delay estimation. This filters the signals to maximise their coherence since the accuracy of the time delay estimates, and thus the height estimates, strongly depends upon the signal coherence. We then consider the fundamental differences between InSAR and InSAS; namely the relative signal bandwidth, aperture sampling rate, and geometry and show how application of generalised correlation time delay estimation leads to the differences in how InSAS and InSAR signals are processed.