In this paper, leakage of pulses through the outer sheath of a coaxial cable was examined empirically. Corresponding to two kinds of propagation constants, there must be two modes of propagation, which was observed in the experiments. Because of the difference of their propagation speeds, the leak waveform changes the shape as the propagation. It was shown that a ferrite toroidal core works effectively as a suppressor for the noise current, and the cores work more effectively if they are spreadly located over the cable length because the leaking wave increases during the propagation on tha cable. The penetration phenomena of outer EM waves into the cable were also observed. These empirical results revealed that the EM waves which had once got into the cable were hard to remove. So the cores as the noise reduction parts should be set at the nearer point to the EM source.

A principle of new Parallel Fourier Transform (PFT) system using a differential transform matrix (DTM) is presented, and its hardware implementation is carried out. The PFT is one of the methods which can execute real-time Discrete Fourier Transform with a low-cost parallel processing. In this paper, the derivation of PFT using DTM is mentioned from the original PFT using polyphase system. It is shown that the PFT using DTM can execute the DFT by 2.5N digital additions or subtractions (where N is the number of input signal points) for each Fourier component, and its hardware is shown. Finally a typical experiment of the PFT is presented.

The reception level of a round-trip signal from a VSAT (Very Small Aperture Terminal) was monitored continuously for three years starting October 1991.For these experimental measurements, a commercial satellite channel (up-link 14GHz/downlink 12GHz, bandwidth 100kHz) was used and rainfall was measured simultaneously. Data gathering time interval of 2 seconds was adopted to elucidate very rapid variation and lower percentage statistics. In this paper, attenuation due to rainfall is shown using the data obtained in this three-year period. It is shown that so far, the measured rain attenuation agrees very well with the values estimated using the CCIR model, and limits the range where the cumulative time exceeds 0.01%, even for our VSAT system in Tagajo, Miyagi Prefecture, Japan.

In this paper, an argumental approach is introduced for an expression of correlation functions between two arbitrary codewords. The real parts of the correlation values are mapped onto the argument vector, then the components of the vector are plotted on a unit circle by each angle. The imaginary parts are expressed on the another unit circle by the same manner. The distinctive features of the proposed method are described in comparison with recent expression methods, and some examples of the application are demonstrated along with numerical results. The argumental expression is shown to be a generalized way to indicate correlation functions for all possible codewords.

For grasping the electromagnetic environment, the visualization as a pattern of electromagnetic field distribution is effective. Generally, the electromagnetic field distribution pattern is composed of several fields caused by different electromagnetic wave sources. In this paper, a method of pattern decomposition of overlapped electric field pattern is proposed. This method is based on the least square estimation of intensity of electromagnetic wave sources under the assumption that the location of every source has been given. The estimation formula of electric field intensity of sources is derived. This method is applied to decompose the real patterns measured in semi-anechoic chamber. These experimental results show that the method of pattern decomposition can be used to eliminate or extract the unwanted reflected and scattered field with less error.

This letter deals with a newly developed automatic system, which measures the rate of malfunction of digital circuits owing to noise induced by breaking electric contacts. In this system, a personal computer is used for the detection and the count of the malfunction in the digital circuit. Its experimental results are reported here.