Parallel Viterbi Decoding Implementation by Multi-microprocessors

The Viterbi algorithm is a well-established technique for channel and source decoding in high performance digital communication systems. However, excessive time consumption makes it difficult to design an efficient highspeed decoder for practical application. The central unit of a Viterbi decoder is a data-dependent feedback loop which performs an add-compare-select (ACS) operation. This nonlinear recurrence is the bottleneck for a high-speed parallel implementation. This paper describes the implementation of parallel Viterbi algorithm by multi-microprocessors. Internal computations are performed in a parallel fashion. The use of microprocessors allows low-cost implementation with moderate complexity. An organization network, separate memory blocks and programs provide proper operation. For a fixed processing speed of given hardware parallel Viterbi decoding allows a linear speed up in the throughput rate by a linear increase in hardware complexity

Wave normal direction of auroral hiss observed by the S-310JA-5 rocket

Wave normal directions of auroral hiss observed by the S-310JA-5 rocket are analyzed from the spin modulation data of electric field components picked up by a dipole antenna extended perpendicular to the rocket axis, and the angle between the wave normal direction and the rocket axis observed by the crossed loop antennas which are both perpendicular to the rocket axis. It is found that the wave normals were making large angles to the magnetic meridian plane, so that the ray paths tracing back to the source indicate an altitude which is not above 700km, when the electron and ion temperature are less than 800K. The electron density between 200km and 230km actually observed by same rocket showed a density gradient much less than that represented by the plasma temperature of 800K. This point will support our result for the source altitude of auroral hiss observed by rocket

Statistical feature of non-ducted Omega signal and associated ASE observed by ISIS-I and -II satellites

Non-ducted Omega signals and associated ASE (Artificially Stimulated Emission) triggered by the Omega transmitter located at Aldra (66°25′15″N, 13°09′10″E, geographic) in Norway were observed by ISIS-I and -II satellites. During the period from May 30,1976 to February 8,1980,VLF data including Omega signals were obtained for 42 out of 642 passes. VLF emissions triggered by the Omega transmitter were detected only for 8 passes out of these 642 passes. Most of the 42 passes were observed within ±15°of geomagnetic meridian through Aldra. Furthermore, the probability of the Aldra signal detection is relatively high in the daytime and for low Kp value mostly less than 3. IN spite of the fact that Aldra is located in high latitude, the delay times of direct pulses to ISIS-I and -II satellites in the conjugate hemisphere were between 0.8 and 1.5s in the L range of 2.4 to 4. The beginning latitude of each frequency component indicates that the frequency coincides with a quarter of minimum electron gryofrequency on a field line passing through the observing point

A Future Plan of Rocket Observations in Antarctica

Before planning future rocket exoeriments at Syowa Station in Antarctica, the IMS rocket projects already partly made and partly to be made at Syowa Station have been critically examined. For the post-IMS project, it is first proposed that the bandwidth of data transmission by rocket telemetry must be widened by powering up of the rocket-borne transmitter and by reconstructing the ground-based telemetry receiver. As to the kinds of observation, almost all IMS projects will be tried again with improving reliability of the experiments. A big comnlex payload will become feasible by an appearance of the S-500 type of rocket

S-310JA-1 and 2 Rocket Experiments : General Introduction and Summary (e. Event Session) (Proceedings of the Second Symposium on Coordinated Observations of the Ionosphere and the Magnetosphere in the Polar Regions : Part II)

The first part of this report summarizes the results of observations of waves and particles by means of the S-310JA-1 and 2 rockets which were launched both in February at one year's interval. Geophysical data simultaneously observed on the ground are also introduced. In the second part of this report, the correlation of the data, especially those of waves and particles, obtained by various kinds of instruments on board the rockets is described

S-310JA-1 2 ゴウキ ジッケン ガイカツ オヨビ マトメ e. イベント セッション ダイ2カイ キョクイキ ニオケル デンリケン ジキケン ソウゴウ カンソク シンポジウム PART 2

波動-粒子観測ロケットとして,1年あいて共に2月に打ち上げられたS-310JA-1,2号機による観測結果と地上同時観測の結果を概括し,また,まとめでは特に各機器の観測結果の関連性を検討し,また,ロケット観測上期待される波動-粒子の観測データの関連性について述べる.The first part of this report summarizes the results of observations of waves and particles by means of the S-310JA-1 and 2 rockets which were launched both in February at one year\u27s interval. Geophysical data simultaneously observed on the ground are also introduced. In the second part of this report, the correlation of the data, especially those of waves and particles, obtained by various kinds of instruments on board the rockets is described

電離層および外気圏における電波伝播に関する研究

京都大学0048新制・課程博士工学博士工博第40号新制||工||24(附属図書館)京都大学大学院工学研究科電気工学専攻(主査)教授 前田 憲一, 教授 清野 武, 教授 池上 淳一学位規則第5条第1項該当Kyoto UniversityDFA

ISIS-I and ISIS-II observation of emissions triggered by doppler-shifted Norway Omega signals

A great number of VLF spectra were collected by receiving the telemetry of ISIS satellites at Syowa Station, Antarctica, for about 6 years from May 1976 to February 1982. Norway Omega signals propagated in the non-ducted mode to the southern hemisphere and observed by the polar orbiting ISIS-I and ISIS-II satellites have shown very interesting latitudinal characteristics of their positive and negative doppler shift. According to EDGAR (J. Geophys. Res., 81,3327,1976), these characteristics are explicable by taking into account the wave normal direction at the satellite location, which can be estimated from the results of ray tracing. One very important result of our observation is that VLF emissions triggered by positively and negatively doppler-shifted Omega signals were discovered. From the doppler frequency shift of the triggering signal, we can determine their wave normal direction at the satellite as mentioned above, so that we have further tried to estimate their wave normal direction in the interaction region near the equatorial plane, where the triggered emissions are thought to have been generated. One such estimation for the case observed on November 28,1979 results in the wave normal angles at the equatorial plane to be around 10°-30°. Furthermore, in other Omega data, it can be shown that the wave normal angles for large doppler-shifted signals approach about 40°-60°at L<2.7

Intensity and polarization characteristics along the earth\u27s surface for the ELF-VLF waves emitted from a transmission cone in the high latitude

A computer code has been developed, which incorporates a full-wave treatment of down-going ELF-VLF wave injected at any altitude in the ionosphere. Ground conductivity is included as a variable in the code. The code expands a spatially confined electromagnetic wave into a finite set of plane waves. For each elemental plane wave, the field components are calculated by a full-wave method, and the field distribution is obtained by FFT analysis of the full-wave solutions. In this paper, numerical calculations are carried out for both daytime and nighttime ionosphere models in high latitude. The distributions of intensity as well as polarization on the ground are presented in the case that ELF-VLF waves having a spatial amplitude distribution are injected onto the ionosphere

Measurements of the Directions of Propagation Vector and Poynting Flux of Auroral Hiss by Means of the S-310JA-5 Rocket

Directions of the propagation vector and the Poynting flux of auroral hiss at 7kHz were measured by the S-310JA-5 rocket launched on 10 June 1978 from Syowa Station in Antarctica. The observation of the ratio of magnetic field intensity to electric field intensity of the hiss as well as the above-mentioned measurements result in a conclusion that the hiss has propagated down to the rocket with a large wave normal angle to the geomagnetic field so that the source region must be located in the vicinity of the altitudes of the rocket apex. The time variation of the hiss intensity showed a relatively good correlation with the flux of 4.45keV electrons with pitch angles from 3°to 34°