摘要:

AbstractFor fast convolution operations on one‐dimensional signal sequences there is the fast cyclic convolution (FCC) method based on sectioning. Also, for a two‐dimensional signal sequence in the convolution operation of a rectangularly sampled signal sequence and a convolving sequence arranged in rectangular blocks, an FCC method based on rectangular sectioning has been reported. On the other hand, two‐dimensional signals band‐limited over a circular region are sampled hexagonally. This arrangement of the convolving sequence in hexagonal blocks to provide it with 12‐fold symmetry is most effective. This paper describes an FCC method based on sectioning for such types of hexagonally sampled signal sequence and convolving sequence arranged in hexagonal blocks, Presupposing the use of a fast Fourier transformation (FFT) of base number 2 in the discrete Fourier transformation in FCC, two types of FCC (hexagonal sectioning and parallelogrammatic sectioning) are proposed and overlap‐and‐save algorithms for these two are given. Also, it is shown that there exists an optimal sectioning block size for which the number of numerical operations becomes minimum in both methods. Next, for both types, the number of numerical operations are calculated and compared. Due to the limited memory capacity useable in FFT calculation, if convolution is not possible with optimal sectioning, the hexagonal sectioning method is advantageous. However, when the memory size is sufficiently large, it is difficult to say which of the

ISSN:8756-6621    

DOI:10.1002/ecja.4410650402

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

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper proposes an ϵ‐separating nonlinear digital filter (called an ϵ‐filter). This filter is intended for effective filtering of low‐amplitude noise superposed on the signal with sharp discontinuities and can be realized by combining a simple nonlinear element with a conventional linear filter. In this paper, the basic ϵ‐filter and its modifications to a trend‐adaptive filter and a two‐dimensional filter are described. The effectiveness of the new filter is demonstrated by computer simulation. Some of its application to EEG analysis, image processing and coding are

ISSN:8756-6621    

DOI:10.1002/ecja.4410650403

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

年代:1982

数据来源: WILEY

摘要:

AbstractRecently, various methods have been reported for two‐dimensional image enhancement with the development of satellite image and medical image processing. This paper proposes a two‐dimensional filter for the image with a nonseparable autocovariance function in order to reduce the memory storage and processing time. Also, a simple method of estimating the necessary statistics to compose the filter is considered. The proposed two‐dimensional filter is a stable one which satisfies an estimation criterion of unbiasness and minimum variance. Also, the filter introduced here is completely equivalent to the Kalman filter algorithm when the filter parameters a1, a2, a3are such that a3= 0 and a1or a2= 0. Thus, the proposed filter is a natural extension of a classical Kalman filter into a two‐dimensional system. Finally, we compare existing methods with the proposed method by simulation, and examine qualitatively the contention that the estimation accuracy and computation time of the proposed method are superior to the

ISSN:8756-6621    

DOI:10.1002/ecja.4410650404

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

年代:1982

数据来源: WILEY

摘要:

AbstractOne method for realizing a rational transfer function as a lattice digital filter is the procedure of Gray et al. using tap coefficient devices. Use of these devices should be avoided from the viewpoint of minimizing the number of multipliers. We have derived a discrimination condition and divided the structures into two classes; those realizing the rational transfer functions with lattice structures only and those requiring tap coefficient structures. A method is proposed for constructing lattice digital filters based on the state‐variable procedure. This method is systematic and suited for computer‐based design. The analysis is also simple. In the case of a general nth order filter it is shown that the coefficient sensitivity is low and a zero‐input limit cycle never occurs in complement trunc

ISSN:8756-6621    

DOI:10.1002/ecja.4410650405

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

年代:1982

数据来源: WILEY

摘要:

AbstractARQ (Automatic Repeat Request) schemes are methods for controlling the error in data transmission. Among the schemes previously proposed are the selective repeat, the GO‐BACK‐N, and the combinations as well as the modifications of these schemes. The analysis of these schemes has been performed on the basis of a simplified model. This paper presents the analysis of several ARQ schemes using a more complex model which takes into account the long propagation delay (such as satellite links), transmission delay associated with retransmission, the system internal time, and the buffer size of the sending station. A concept of equivalent channel holding time is used in conjunction with a M/G/1 queueing model for the analysis of the system throughput as well as other characterist

ISSN:8756-6621    

DOI:10.1002/ecja.4410650406

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

年代:1982

数据来源: WILEY

摘要:

AbstractWhen an optical cable is installed on an aerial line, it will be affected strongly by the temperature and vibration due to wind. Therefore, it is necessary to grasp these effects quantitatively and establish a design method for the optical cable which will not be controlled by weather conditions. For this reason, we hypothesize a line close to the actual form and construct a 48‐core optical cable using a lashing machine, and then investigate the effects of temperature between ‐20°C and 60°C on the optical cable. The mechanical behaviors of the cable include the following: (1) Relative displacement between the strand and the optical cable accompanies temperature variations. The displacement is approximately 30 mm maximum at the end of a cable 57 m long; (2) Relative displacement between cable sheath and core occurs due to the release of the residual strain during manufacturing. It is 18 mm in the case of a 57 m cable; and (3) About 200 kg thermal stress occurs at the cable end, however, only about 10 kg in the vicinity of the slack. Based on the above experiment, the mechanical behavior of the optical cable is analyzed theoretically by setting up a simple model. It is confirmed that the analytical results agree very well with the experiment results. Variation of optical loss increases at approximately 0.15 dB/km at 60°C and this is about the same change as drum‐wou

ISSN:8756-6621    

DOI:10.1002/ecja.4410650407

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

年代:1982

数据来源: WILEY

摘要:

AbstractIn this report, the line code structures of optical transmission systems are compared from the viewpoint of providing bit sequence independence (BSI). Repeater fault location schemes are also studied. Initially, we shall describe what considerations should be made to avoid consecutive identical codes as well as pseudo‐synchronism in accordance with the inherent meaning of BSI, and we shall show a specialized code pattern to be considered for protecting pseudo‐synchronism and a frame format to avoid pseudo‐synchronism. Furthermore, we shall show the repeater fault location schemes for the phase‐difference‐detection type of CMI code transmission system and the m BIP code transmission system with odd parity, and we shall indicate how simple they are to realize. Then the transmission line code schemes of the 100 Mb/s optical cable transmission system are compared, and it is concluded that the preferable frame format is that in which frame synchronization pulses are inserted at positions different from the parity bits based on the 7 BIP code. In addition, experimental studies of the characteristics of the timing system in the repeater of the DF‐100M system [1] will indicate the appropriateness of the design jitters and the selection of the frame format of t

ISSN:8756-6621    

DOI:10.1002/ecja.4410650408

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

年代:1982

数据来源: WILEY

摘要:

AbstractThis paper explains the input/output power and AM‐PM conversion characteristics of an amplitude limiter using GaAs MESFET. It is also pointed out that the AM‐PM conversion can be minimized conveniently by adding inductance in parallel to the gate terminal. In this paper the FET equivalent circuit is used for a calculation from which the relationship between the AM‐PM conversion and the gate series resistance, driving source impedance and the added inductance is clarified; the design method for minimizing AM‐PM conversion is established. The measured charactersitics are found to be the same as predicted by theory, and the correctness of the analysis is co

ISSN:8756-6621    

DOI:10.1002/ecja.4410650409

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

年代:1982

数据来源: WILEY

摘要:

AbstractA method is presented for broadbanding an n‐way power divider in which an absorbing resistor is used in one section. In the conventional Wilkinson power divider, it is known that the waves, equally reflected at the terminations, are absorbed by a resistor at the center frequency if a quarter‐wave line is connected to one of the output ports. To construct a 2n‐way power divider from a combination of these two‐way power dividers, 2n sections of lines are needed. In this paper, we constructed a network, which absorbs reflected waves, by connecting a 1/4‐wavelength section to an n‐way one‐section power divider if the characteristic impedance of the line and the absorbing resistor are optimized by numerical calculation. The circuit shown in the text has a broadband VSWR characteristic if attenuation of the transfer at the center frequency is permitted. The transmission characteristics then become flat, and the isolation characteristics are

ISSN:8756-6621    

DOI:10.1002/ecja.4410650410

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

年代:1982

数据来源: WILEY

摘要:

AbstractA high‐speed logic circuit, which is compatible on a single chip with I2L (integrated injection logic) and high‐voltage analog circuits is proposed. It is well known that the I2L features low power consumption and high packing density, but that its speed is lower than that of other bipolar circuits. On the other hand, high‐speed bipolar logic circuits consume a lot of power and occupy large area on a silicon chip. This paper proposes a new logic circuit which fills the gap in speed and density between the high‐speed bipolar and I2L circuits and reports the results of experiment. The new logic circuit uses a pnp transistor as a load device and a Schottky‐clamped npn transistor as a driver. An experimental circuit fabricated using an analog‐compatible technology showed a minimum delay time of 1.5 ns and a power‐delay product of 0.5 pJ. A counter circuit was operated at a freque

ISSN:8756-6621    

DOI:10.1002/ecja.4410650411

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

年代:1982

数据来源: WILEY