NHK Spring (Japan)

We are developing a diverse reception system (DRS) to compensate for rain attenuation in satellite broadcasting that utilizes path diversity between a satellite channel and a best-effort (BE)-IP network for end users. The proposed DRS recovers signals lost on a satellite channel due to significant rain attenuation by supplementing them via a BE-IP network. The unique point of the DRS is that it uses a common forward error correction (FEC) for both channels by applying a FEC for satellite broadcasting to the error correction in BE-IP network. This allows both channels to be integrated at the FEC layer and improves the quality of service (QoS) in the satellite broadcasting thanks to sharing the decoding information between the two. In this paper, we propose an advanced error-correction technique that achieves a high QoS in the DRS by sharing each loglikelihood ratio (LLR) utilized for the FEC decoding of bits received over both channels. This technique, which we call the LLR sharing method, enables successful error correction even when neither a satellite channel nor a BE-IP network can individually achieve error-free transmission due to significant rain attenuation or burst packet loss, respectively. Computer simulation results confirm that the LLR sharing method can improve the required C/N in the satellite broadcasting. In addition, we discuss how to suppress the load of the BE-IP network and integrate both channels efficiently.

In this paper, we present a prototype transmitter and receiver with set partitioning (SP)-64 amplitude and phase shift keying (APSK) coded modulation we developed for expanding satellite transmission capacity. SP-multi-level coded modulation is a transmission scheme that can improve noise immunity by properly combining a modulation scheme, bit allocation, and error-correction codes. We designed SP-64APSK coded modulation on the basis of channel capacity for expanding satellite transmission capacity. We confirmed that it has higher robustness to additive white Gaussian noise (AWGN) than DVB-S2X’s 64APSK modulation with Gray mapping through computer simulation. We also developed a prototype transmitter and receiver to implement our SP-64APSK coded modulation and evaluated its transmission performances in an AWGN channel and in a non-linear channel simulating 12-GHz-band satellite transponder characteristics. We describe the method of designing our SP-64APSK coded modulation through computer simulation, the modulation/demodulation process, and transmission performances of the prototype transmitter and receiver. We also indicate that 8K ultra-high definition television (UHDTV) with an encoded bit rate of 150 Mbps can be transmitted using the prototype within 34.5 MHz, which is the bandwidth of a single transponder for satellite broadcasting in Japan.

Abstract A wide range of de novo protein structure designs have been achieved, but the complexity of naturally occurring protein structures is still far beyond these designs. To expand the diversity and complexity of de novo designed protein structures, we sought to develop a method for designing “difficult-to-describe”α-helical protein structures composed of irregularly aligned α-helices like globins. Backbone structure libraries consisting of a myriad of α-helical structures with 5- or 6-helices were generated by combining 18 helix-loop-helix motifs and canonical α-helices, and five distinct topologies were selected for de novo design. The designs were found to be monomeric with high thermal stability in solution and fold into the target topologies with atomic accuracy. This study demonstrated that complicated α-helical proteins are created using typical building blocks. The method we developed would enable us to explore the universe of protein structures for designing novel functional proteins.

In this study, we develop an air suspension with a variable length slit restriction and make clear its dynamic characteristics. The proposed air suspension can provide the optimum equivalent damping coefficient by automatic damping adjustment mechanism. The optimum equivalent damping coefficient, which provides the minimum resonance amplitude, increases as mass of supported object increases. The damping coefficient can be varied by varying slit length of restriction. In order to vary slit length, the damping adjustment mechanism consists of a fixed plate, which has a partially circular groove, and a rotating flat plate faced to grooved plate. The variable length partially circular slit is foamed by two plates. The damping coefficient is almost proportional to an adjustment angle of the rotating flat plate in the adjustment mechanism. The adjustment angle which provides the minimum resonance amplitude can be obtained by simplified equation of the supported mass. The proposed system consists of the air suspension, two pressure gauges measuring atmospheric pressure and static pressure in the cylinder, the damping coefficient tuning mechanism, a servo motor rotating the flat plate to tune the adjustment angle and a micro-computer calculating the optimum adjustment angle using signals of the pressure gauges. Even if the mass increases up to the third of the nominal value, the minimum resonance amplitude is archived using adjustment mechanism.

A superconducting joining method for high-temperature superconductors (HTSs) is one of the key technologies needed to realize persistent current operations in HTS magnets such as NMR and MRI. We have succeeded in developing a practical superconducting joining method between REBa2Cu3Oy (REBCO, RE: rare earth elements)-coated conductors with a microcrystalline REBCO precursor intermediate layer. The microcrystalline REBCO precursor intermediate layer is sandwiched between c-axis oriented REBCO layers and is joined with them. The crystal growth process during heat treatment has been investigated by observing cross-sectional views of the precursor layer. Cross-sectional TEM images showed that the precursor grew epitaxially from both the upper and lower surfaces of the c-axis-oriented REBCO layers. Then the entire precursor grew with both of the REBCO layers being joined with c-axis orientation. The iGS joint gives a critical current of >70 A at 77 K under self-magnetic fields. The total processing time, including joining heat treatment and oxygen annealing, is less than one day. This joining method allows us to operate a 400-MHz (9.4 T) HTS NMR magnet with a sufficiently stable magnetic field, and thus we have succeeded in obtaining NMR spectra.

For the 2020 Tokyo Olympics and Paralympics, NHK is preparing 8K devices for 8K regular broadcasting. However, the equipment is in the early stages of development; therefore, it is necessary to continue improving their performance and operability. Particularly, the sizes of the cameras and lenses are larger than those for HDTV. Furthermore, handling uncompressed data is challenging because of the sheer size of the data. In this presentation, we introduce the current 8K UHDTV technologies that are closely related to photonics technology and the challenges for its development. Moreover, we describe our expectations for the research and development in the field of photonics.

The design and development for a compact 1 GHz (23.5 T)-class NMR magnet are presented. The magnet uses inner coils wound with Ni alloy-reinforced Bi-2223 conductors in combination with LTS outer coils. The series-connected coils are operated in a power supply-driven mode. The total magnet size is very compact, and is comparable to that of a currently commercialized 600-MHz (14.1 T) NMR magnet. This owes to a high current density operation of the Bi-2223 inner coils, which contribute as much as 53% of the total magnetic field. This paper investigated the following properties of the Bi-2223 inner coils: First, joint resistance under external magnetic fields; second, tensile stress tolerances of the Bi-2223 conductor under bending condition; third, high compressive stress on Bi-2223 coils; fourth, the effect of screening current-induced magnetic field on the field homogeneity and stability; and fifth, the maximum permissible Joule heating to avoid a thermal runaway. Two Bi-2223 inner coils for the magnet were built and tested in liquid nitrogen, which provided important knowledge for the magnet excitation.