摘要:

AbstractThe application of error‐correcting codes to the DCPSK system is discussed. Nakamura and Iijima have proposed a method in which the block code to be applied inside the differential coding is applied outside the differential coding. The method of Nakamura and Iijima is first investigated in detail from the viewpoint of coding theory. Based on the results it is shown that a paired error‐correcting code can be constructed in the block code from the random error‐correcting code by a linear transformation. Then, applying this to the convolution code, a method is devised for constructing the generating matrix for the paired error‐correcting code by carrying out a linear transformation of the generating matrix for the random error‐correcting code with differential coding. Search for a convolution code to be used in the DCPSK system is made on a computer. Finally, a code is constructed which can successfully correct the error caused by reference phase slip in synchronous detection as well as by random error in the channel. The usefulness of the code in the DCPSK system is dem

ISSN:8756-6621    

DOI:10.1002/ecja.4400651002

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper presents an automatic equalizer consisting of transversal‐type circuits which uses a block‐iterative algorithm for tap‐gain adjustment. The taps of an FIR filter are divided into groups. The proposed algorithm seeks the optimum tap gain for each group in one step. This algorithm may be regarded as an extension of the Gauss Seidel algorithm, which is a solution method for first‐order simultaneous equations. Unlike the ordinary steepest‐descent method, it is guaranteed to converge to the global optimum even for transmission lines having totally unknown channel distortion. Computer simulations reveal that the block‐iterative algorithm, by allocating two to three taps in a group, converges faster than the ordinary steepest‐descent method and requires fewer comput

ISSN:8756-6621    

DOI:10.1002/ecja.4400651003

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractWhen a unit impulse is incident on a constant‐resistance distributed coupled‐line network consisting of equally long multisection two‐wire coupled lines and a π‐type resistive network, the output response is an infinite pulse train with diminishing amplitudes. With an appropriate choice of element values it is shown that the amplitude ratio of a first few pulses is (1, Om, 1), (1, Om, ‐1), (2, Om, 1, Om, ‐1) and (1, Om, 2, Om, 1) and the remaining pulses become negligibly small. These first few pulses are considered to be signal components with the remaining pulses constituting the characteristic wave distortion. It is possible to reduce this distortion by increasing the number of coupled line sections. In this paper, the distortion rate is defined as the ratio of the characteristic wave distortion power to the signal power. With the total reflected power of the circuit expressed in terms of a complex integral, calculation of the distortion rate is possible. We quantitatively characterize the operational circuit as a symbol converter. Calculations have been made for coupled lines with up to 4 sections. Since the formulation becomes complicated as the number of sections increases, the numerical calculations are made o

ISSN:8756-6621    

DOI:10.1002/ecja.4400651004

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractFerrite is a non‐reciprocal material which is used in non‐reciprocal devices such as isolators or circulators for the microwave and optical bands. Waveguides containing ferrite, are usually analyzed by 2‐dimensional approximations but not by 3‐dimensional analysis. This paper utilizes a mode‐matching method to analyze ferrite image lines, and the analysis is compared with experiment. First, the mode‐matching method is applied to the mode analysis of a ferrite slab and we find its dispersion and field distribution. These modes are then used to analyze the image waveguide, especially its field patterns, which are quite different from those for the dielectric case; finally its validity is confirmed by

ISSN:8756-6621    

DOI:10.1002/ecja.4400651005

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractIt is important in determining system configuration to understand the length dependence of the baseband bandwidth of a graded‐index fiber. An actual fiber communication system is constructed from a number of connected fibers with different characteristics. In such cases, the length dependence of the baseband bandwidth becomes very complex due to mode conversion and mode dispersion compensation at the junction and no practical method exists to estimate the characteristics. Therefore, actual systems are approximated by setting an appropriate value of γ in the γth power expression. This paper first finds the length dependence (γ value) of the baseband bandwidth measured in a number of fiber systems actually installed. Next, to analyze factors determining the length dependence, experimental and theoretical investigations are conducted. It is found that an important factor determining junction characteristics is the mode dispersion compensation regulated by the group delay difference among principal mode groups as well as within a principal mode group. It is also found that mode conversion at the junction has a negligible effect. In an actual communication channel employing many fibers, correlation in the group delay difference among the principal mode groups and within the principal mode group of each fiber becomes small and the value of γ is restricted. In practice, it is possible to estimate the average baseband bandwidth by setting γ

ISSN:8756-6621    

DOI:10.1002/ecja.4400651006

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractIn this paper, a tube‐contacted slab dielectric waveguide for millimeter waves is proposed, and a theoretical analysis and experiments are performed to determine the propagation characteristics. This waveguide consists of a dielectric tube with its radius larger than the wavelength, placed on a guiding film. The guided wave energy is concentrated near the contact point between the tube and the film. Since the tube is easily bent due to its structure and the field distribution is similar to Gaussian, the structure can be used as a low‐dispersion flexible dielectric waveguide. Also, since the tube radius is larger than the wavelength, the waveguide can be used for high power transmission. The effective dielectric constant method has been used for analysis, and the field distribution and the phase constant have been computed. A waveguide has been fabricated for 35 GHz and the field distribution, propagation loss, guide wavelength, the field distribution at a bend and the bending loss have been measured. Measured results of the field distribution, guide wavelength and bending loss have agreed well with theoretical predictions. The propagation loss is 1.52 dB/m. In addition to the bending loss, variations of the field distribution at the transition from the straight guide to the bend have been measured. Based on these measured results, it is shown that the waveguide can be used for low‐dispersion flexible transmission line or for high power transmi

ISSN:8756-6621    

DOI:10.1002/ecja.4400651007

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractMicrostrip line slot‐array antennas consisting of slots placed on the ground plane on both sides of the microstrip line may be classified into resonant‐ and nonresonant‐types. Both types exhibit a beamtilt—namely, the main beam direction shifts as the operating frequency is changed away from the center frequency. This beam‐tilt causes the gain in the specified direction to degrade rapidly, which is a serious drawback in a system for receiving a signal with a given bandwidth from a fixed direction. To overcome this deficiency, a method available for waveguide slot‐array antennas is used and a design procedure is developed. Further, it is shown experimentally that beam‐tilt is almost nonexistent over a relatively broad frequency range and constant gain is obtained. The gain is higher than that of conventional antennas. Sidelobes are suppressed, especially for nonresonant arrays. The usefulness of the microstrip line slot‐array antenna with a reduced beam‐til

ISSN:8756-6621    

DOI:10.1002/ecja.4400651008

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe large change in the characteristics of MNOS memory results from the variation of the trapping level charge in the interface of SiO2and SiN with time. Thus, MNOS memory has the drawback of short life. It is difficult to understand the change in the aging characteristics by means of functional tests, but for digital LSI the operation‐limited supply voltage variation method can be used to characterize the variation of intrinsic device characteristics.In this paper the above‐mentioned method is actually applied to the MNOS memory, and a capacitor charging and discharging model is proposed to quantify the aging‐caused changes. The agreement between the test results and the model, the activation energy for the changes, as well as the calculation method for the lifetime are presented.It is shown that the MNOS device change can be estimated by the operation‐limited supply voltage test method, the magnitude of the change in the characteristics due to aging is modeled as an exponential function exp (‐t/τ) with respect to the time t and time constant τ, which can be shortened with an increase in temperature. Its activation energy is found to be 0.2 eV and the life is propor

ISSN:8756-6621    

DOI:10.1002/ecja.4400651009

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractThe single‐mode optical fiber, which has stable polarization characteristics, is one of the most important components in the high‐density optical communication system, and R&D interest is focused intensively on this component. This paper presents a vector mode analysis of a fiber with arbitrary refractive index distribution and without axial symmetry, such as an elliptic fiber with arbitrary refractive index distribution, which has been mentioned as one possible optical fiber. An approximate vector solution is proposed. The approximate vector analysis is a practical method of analysis, in that the numerical computation required is that employed in the approximate scalar solution itself, which is simple and obvious, since most of the computation is analytic, and it is possible to determine directly the difference of propagation constants of the two vector modes in the single‐mode optical fiber. The paper discusses the theory, accuracy and application of the approximate vector ana

ISSN:8756-6621    

DOI:10.1002/ecja.4400651010

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY

摘要:

AbstractIt is shown that when an external force is impressed on a single‐mode optical fiber to produce an axially symmetrical internal stress there is no coupling between left‐and right‐circularly polarized waves propagating in the fiber. It is also shown that the external force only affects the propagation constant, especially the phase constant, and its effect is equal for each circularly polarized wave. Based on those results the external force is shown to have no effect on the polarization characteristics of the fiber. The reflection for each propagation, mode affected by the external force is discussed, and the effect appears to be negligible. Finally, as a polarization‐maintaining method it is proposed that optical fiber holders that create these stresses be used—such as chuck‐ or shrin

ISSN:8756-6621    

DOI:10.1002/ecja.4400651011

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1982

数据来源: WILEY