Shusou Wadaka

A high resolution ultrasonic range measurement method using double frequencies and phase detection

An ultrasonic range measurement method is presented which uses a pair of transmit signals with different frequencies from each other and phase detection of a pair of received signals corresponding to the pair of transmit signals, respectively. Uncertainty of detected phases in relation to integral multiples of 2 /spl pi/ is eliminated using the pair of phases and one of the envelopes of the received signals. High resolution can be obtained since the range is detected based on the information of the phases of the received signals. Experiments were done in air using the frequencies of 180 kHz and 210 kHz, and resolution of 1% of the wavelength corresponding to the frequency of 210 kHz was obtained.

Performance of Discrete-Fourier-Transform-Based Velocity Estimators for a Wind-Sensing Coherent Doppler Lidar System in the Kolmogorov Turbulence Regime

The performance of discrete-Fourier-transform (DFT)-based velocity estimators for wind-sensing coherent Doppler lidar systems in the Kolmogorov turbulence regime is summarized using Monte Carlo simulations. Furthermore, a signal model, a simulation procedure, velocity estimators, and simulation conditions are explained. The relationships between signal-to-noise ratio, line-of-sight velocity estimation precision, and signal detection probability are simulated and summarized. In addition to the basic DFT estimator, signal matching estimators which utilize DFT are studied. The performances in the Kolmogorov turbulence regime and those in the Gaussian autocovariance signal model are compared. The performances are compared for wavelength regions of 1.5, 2, and 10 mum.

Film bulk acoustic wave filters using lead titanate on silicon substrate

A film bulk acoustic wave resonator and filter at GHz frequencies is reported. The resonator and filter employ lead titanate (PbTiO/sub 3/) as the piezoelectric thin film. The films are formed by RF magnetron sputter deposition on silicon (Si) substrates. Platinum (Pt) is used as top and bottom electrodes. The thickness of the piezoelectric film is about 1 /spl mu/m, and that of the electrodes is 0.1 /spl mu/m. The chip size of the resonator and filter is 0.69/spl times/0.55 (mm). The resonant frequency of the fabricated resonator is 1.4 GHz. The top electrode size of the resonator is 50/spl times/50 (/spl mu/m), and the quality factor Q is about 70. The insertion loss of the fabricated filter is 13.6 dB at the frequency of 1.5 GHz, and the 3 dB bandwidth is 47 MHz.

Ink mist jet generation using low frequency focused ultrasonic waves and nozzle

A print head using low frequency focused ultrasonic waves and a nozzle has been recently reported, In this paper, the efficiency of the print head is analyzed to achieve efficient electroacoustic conversion and efficient focusing. In the analysis of the electroacoustic conversion using a piezoelectric transducer, the KLM equivalent circuit is used. In the analysis of the focusing process using a reflection wall, a sound ray tracing model is used and a complex reflection coefficient at each point on the reflection wall is taken into consideration. A print head operating at 10 MHz is fabricated based on the analysis. The sound pressure is measured using a hydrophone placed at the focal point. The measured sound pressure is in good agreement with that of the calculated one. The loss of the fabricated print head is estimated to be about 4 dB.

Microwave properties of La-doped lead titanate piezoelectric films for bulk acoustic wave resonators

The bulk acoustic wave resonators at GHz bands were fabricated by using La-doped and non-doped lead titanate piezoelectric films which were deposited by RF magnetron sputtering method. Though crystallinity of the La-doped PT film was inferior to that of the non-doped PT film, the dense and pore less film with columnar structure was obtained. The non-doped PT film had superior crystallinity, but some pores were observed. Resonances for the bulk acoustic mode occurred around 1.4 GHz. The electrical Q of La-doped and non-doped PT films were estimated to be 100 and 70, respectively. By doping La, the dense PT films were obtained and the improvement of the Q value was accomplished.

A SAW contiguous filter bank with an m derived ladder

An m-derived ladder for combining SAW (surface acoustic wave) filters in a contiguous filter bank is proposed. The series element in each m-derived ladder section is composed of a parallel resonant circuit. The input transducer of a SAW filter is used as the shunt element in each section. A pole of attenuation is produced at the resonant frequency of the series element. Thus, the third-harmonic spurious response of the SAW filter is greatly suppressed by setting the pole of attenuation in the vicinity of the third harmonic. A ten-channel version of the filter bank was constructed, operating in the frequency range from 110 to 200 MHz. The insertion loss was 10+or-1.7 dB, which was as low as that of a constant k ladder filter bank, and the attenuation was greater than 42 dB in the third harmonics from 330 to 600 MHz.<<ETX>>