ATM's bandwidth flexibility and high switching speed advantages have made it the preeminent solution to the B-ISDN. However, networks based on ATM suffer from phenomena not encountered in the STM network, e.g., cell loss, and cell jitter. For ATM to support varied media, problems arising from these phenomena must be resolved. This paper discusses techniques which enable ATM to support CBR, VBR voice, VBR video, and connectionless services. We determine the problems to be resolved for each service and discuss solutions. We focus on dejittering and clock recovery for CBR service, on talk-spurt synchronization for VBR voice, and on video frame synchronization and lost-cell compensation for VBR video service. We show experimental results for a prototype HDTV codec and terminal adapter. For connectionless service, we show that connectionless service should be supplied by the B-ISDN itself using message handlers which support message routing and addressing, i.e., connectionless service functions (CLSF), as described by the CCITT. We propose a network topology of message handlers, which reduces the routing database and avoids transit message handler overload. We show an example of system configuration for connectionless service.

A technique was developed to reconstruct the cross-sectional image of the absorption distribution in a diffuse medium using backscattered light. In this technique, we illuminate an object with an ultra-short pulse, and measure the time-resolved pulse shape of the light backscattered from the object. The absorption distribution of the scattering object can be estimated using the propagation-path distribution of photons at each detection time and the optical impulse response of backscattered light. In a simulation, the effectiveness of this technique was verified in the cases of a layered absorber and a three dimensional absorber. The nonlinear relationship between the depth of the probing region and the propagation time was clarified. The accuracy of the image reconstruction was significantly improved by the aperiodic sampling of the backscattered impulse response according to the nonlinear relation. The feasibility of the proposed technique was verified in the experiment with a model phantom.

A color subcarrier in a television (TV) signal via a broadcasting satellite is expected to be an effective medium for future frequency dissemination. The difficulty inherent in use of the broadcasting satellite is the Doppler shift due to the drift around the geostationary orbit. Therefore, it is important to measure the Doppler frequency shift of the color subcarrier precisely and to establish a technique which cancels out the effect. The Doppler frequency shift measurements were carried out by using a Medium-Scale Broadcasting Satellite for Experimental Purposes (Yuri). This paper reports the results observed at Sapporo. The important results are as follows. The Doppler shift amounts to about 1108 in the worst case. However, when the transmitted frequency is controlled at the Kashima transmitting station, the Doppler shift may be canceled out to within a few parts in 1010 at Sapporo. Furthermore, it is expected that we may usually obtain the standard frequency with an accuracy of the order of 1012 if the Doppler shift compensation is employed at both transmitting and receiving points. These results are important when we construct a nationwide frequency dissemination system using a broadcasting satellite.