[in Japanese]

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[in Japanese]

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A microstrip antenna with a small size and light weight is useful for wireless cameras. The antenna used for wireless cameras is required to have a gain of 10-12 dBi. To get a gain of 10-12 dBi, the microstrip antenna is usually constructed in a planar array. However, it can be also made by arraying a parasitic element in the radiating direction over the radiator. On the other hand, the impedance bandwidth of the antenna increases by locating a parasitic element over the radiator. In this papar, we propose a microstrip antenna composed of three elements : the radiator, the first parasitic element to widen the bandwidth of impedance and the second parasitic element to increase the gain. The characteristics of this stacked antenna are investigated experimentally and the utility for a wireless camera system is discussed.

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A new model-based coding system for video-telephone and video-conference systems is proposed. In this system, a facial image in the remote terminal of a speaker without any specific expression is transmitted over a telephone line, and a wireframe model of the face is made and stored in the receiving terminal in advance of a conversation. During the conversation, displacement of 34 feature points on the speaker's face is measured and transmitted to the receiving terminal. Also, by modifying the wireframe and model image with this displacement data, the speaker's facial image is reconstructed. Parallel with the displacement data, isodensity lines delineating equal gray level picture elements in the facial image are transmitted and used to compensate density errors in the reconstructed images. There images are generated by changes of surface angles between the facial parts and the illumination source resulting from facial expressions.
This system requires 19 kbps to transmit the facial images, and the quality of the output images in this system is excellent.

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This paper introduces an example of telecommunications for the hearing impaired, which is realized by transmitting speech parameters using a telephone channel and by synthesizing them as a visually integrated pattern in the receiving side.
The realized speech-visualization system and the features in the patterns are briefly described, and then the data format for the transmission by a telephone channel is discussed. The data format is determined on the basis of a transmission rate, a real-time representation and bit-allocations of the speech parameters.
The results show that if about a 100 ms delay time is permitted, it is possible to make the chromaticity change by quantization below the just noticeable difference.
Finally, possibilities for the communication are investigated by word tracking tests. Based on those results, we conclude that a person can understand the patterns well if the speaker talks slowly making pauses.

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As an aid with which a hearing impaired person can understand telephonic speech, a speech visualization system is being developed. This paper describes methods to estimate speech parameters that include the third formant frequency (F₃) and pitch frequency (F₀). These frequencies are necessary to realize the system, but may not exist in the telephone frequency band.
The third formant frequency is estimated from the first and second formant frequencies by a quadratic equation based on the analysis of multiple regression. For the pitch extraction, we have proposed a method to restore a fundamental component from the harmonic ones using a nonlinear processing and also to measure the periods.
According to the examples of short sentences processed by the above methods, the third formant trajectories and the pitch patterns in telephonic speech almost agree with those in real speech which is recorded at the same time.

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[in Japanese]

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[in Japanese]

View full abstract