Detection and Parameter Estimation Analysis of Binary Shift Keying Signals in High Noise Environments.

In this paper, a new method for detecting and estimating the parameters of a binary phase shift keying (BPSK) signal, based on a cross-correlation function, is proposed. The proposed method consists of two stages. The first stage is used to detect or estimate a signal carrier frequency, and the second stage is used to estimate its pulse width or symbol rate. Firstly, the proposed method is investigated by use of a simulated BPSK signal in the form of Barker Codes 7, 11, and 13 in the MATLAB environment. Based on the simulation results, the functionality of this method is verified using a real-time BPSK signal generated by an E8267C generator. This is described in the second part of this paper. The experimental test results confirm that the proposed method is able to detect and estimate the parameters of all BPSK signals with SNR≥−21 dB.

Precise experimental determination of electrical equivalent circuit parameters for ultrasonic piezoelectric ceramic transducers from their measured characteristics.

The letter is devoted to a method for determining electric equivalent circuit parameters of piezoelectric ceramic transducers from their resonance characteristics. These parameters represent equivalents of mechanical damping, effective weight of the oscillating element, compliance of the mechanical element and static capacitance associated with the transducer material. This method is considered cost efficient, focuses on transducers commonly available on the market and is presented on a specific transducer - transmitter. The acquired parameters are important for performing subsequent simulations and defining their suitability for a particular application. However, these parameters are not included in the usual technical documentation of the commercially available piezoelectric ceramic transducers. The key part of this letter is an iterative process of finding the parameters. Before starting the iteration process, it is very important to set default values of these parameters. Then, a linearized system of equations, based on expressing a real part of the impedance, is used to determine these parameters. The advantage of this method is its simplicity to measure only the two above-mentioned characteristics, from which the required parameters can be then calculated. Thus, there is no need for expensive circuit analyzers, which are able to determine these parameters directly. Although the iterative process includes a large number of steps, and therefore can be relatively time consuming, it can be performed on a commercially available computer technology.

Phase-Coded Modulation-Based Time-of-Flight Measurement Improvement for Piezoelectric Ceramic Transducers.

Ultrasonic time-of-flight (ToF) measurement is commonly used in a variety of scenarios when using small bandwidth ultrasonic transducers with 40-kHz central frequency. With these transducers, the threshold detection technique is commonly implemented, but the small bandwidth can cause inaccurate results. This article proposes a variant of correlation method for the improvement of the ToF measurement accuracy and stability with these transducers. Barker 13 and derived codes are proposed for this purpose, together with the selected code band narrowing techniques. The performance of these codes was evaluated experimentally, where 1000 measurements of each code and modulation schemes took place in several fixed transmitter-receiver settings. As the main criterion for comparison of the performance of the codes and the threshold detection technique, a sample standard deviation (SSD) was selected, showing the stability of the measured results. The best results were produced by quadriphase codes and codes with implemented fluent phase change technique, where the measured SSD was smaller than 20% of the SSD of the threshold detection techniques with all the used codes and was also smaller than 10% for the best-recorded cases.