Subjective quality tests have proven that embedded adaptive differential PCM (ADPCM), known to tolerate information loss through bit dropping, does not maintain sufficient speech quality when directly applied to asynchronous transfer mode (ATM) due to the fixed-length cell transmission scheme unique to ATM. We propose a coding and transmission scheme which enhances the performance by adjusting the embedded ADPCM coding rate according to input speech characteristics, thereby taking advantage of the ATM environment, where the transmission of variable rate sources is feasible. By varying the number of code bits of an embedded ADPCM coder from 6bits per sample, or 48kbps, for blocks of speech with a high prediction gain, to 2bits, or 16kbps, for silent blocks, a good compromise between coding bit rate and speech quality with gradual degradation due to information loss is achieved. The results of subjective evaluation tests showed the speech quality of the proposed scheme to be over 3.5 mean opinion score (MOS) on a scale of 1 to 5 at a cell loss rate of 10%. A prototype of the codec and the ATM cell assembly/disassembly functions were also fabricated using 3 conventional digital signal processors (DSPs) for real-time conversation tests.

Superconducting Transition edge sensor (TES) coupled with a heavy metal absorber is a promising microcalorimeter for Gamma-ray (γ-ray) spectroscopy with ultra-high energy resolution and high detection efficiency. It is very useful for the non-destructed inspection of the nuclide materials. High resolving power of γ-ray peaks can precisely identify multiple nuclides such as Plutonium (Pu) and Actinides with high efficiency and safety. For this purpose, we have developed the TES coupled with a tin absorber. We suggest the new device structure using the gold bump post which connects a tin absorber to the thermometer of the superconducting Ir/Au bilayer. High thermal conductivity of the gold bump post realized strong thermal coupling between the thermometer and the γ-ray absorber, and it brought the benefit of large pulse height and fast decay time. Our TES achieved the good energy resolution of 84 eV FWHM at 59.5 keV. Using this TES device, we also succeeded to demonstrate the nuclear material measurements. In the measurement of a Pu sample, we detected the sharp γ-ray peaks from 239Pu and 240Pu, and of a Fission Products (FP) sample, we observed fluorescence X-ray peaks emitted by the elements contained in FP. The TES could resolve the fine structures of each fluorescence X-ray line like Kα1 and Kα2. In addition to that, we developed the TES coupled with tantalum absorber, which is expected to have higher absorption efficiency for γ-rays. This device reported the best energy resolution of 465 eV at 662 keV.