@article{oai:jaxa.repo.nii.ac.jp:00035134,
 author = {東口, 實 and HIGASHIGUCHI, Minoru},
 issue = {8},
 journal = {東京大学航空研究所集報},
 month = {Dec},
 note = {機上ドプラレーダ受信信号について理論的に解析し,従来いわれていた受信信号が濾波器を通過した雑音信号に等しいという点について検討したものである.第2章においては相対性理論に基づく効果を考慮に入れて地表面における単一の反射体からの受信信号を位相おくれおよび周波数変化に重点をおいて検討した.ここでは空中線ビーム方向が一定で航空機が等速直線運動を行なう場合と,空中線ビームが機械的に回転している場合とに分けて取り扱い,特殊および一般相対性理論の効果を見た.その結果このような機上ドプラレーダ受信信号の解析は受信機が静止しているものとして行なうべきことが明らかになった.次に第3章においては空中線ビームに幅があり,したがって多くの反射体からの合成波が受信される場合の受信信号について検討した.個々の反射体からの信号は波束の形を持っていると考えられる.この波束の継続時間は反射体がビーム中に含まれる時間に等しく,かつその瞬時周波数は反射体の方向の変化にしたがって低い方に徐々に変化する.そこで機上ドプラレーダ受信信号のスペクトルは数多くの線スペクトルから出来ており,その包絡線は空中線ビームの形に対応して一定であるが,個々の線スペクトルの位置は刻々変化しているものと考えられる.すなわち無数の反射体が存在すれば連続スペクトルとして観測されるであろう.さらに詳細なスペクトルの成り立ちについてはまだ検討を要するが,一応御報告することとした., The received signal of airborne Doppler radars is analyzed theoretically in this paper. The objective is to clarify a question, why the received Doppler signal has to be characteristics of filtered noise, as was treated so far. In Chapter 2, a rigorous representation of the fundamental received signal is obtained analytically, including the effect of relativity. Two cases are cosidered herein: Case 1. An aircraft carrying a fixed antenna flys on straight line and with a constant velocity. Case 2. An airborne antenna beam directed to the ground is rotated conically with some mechanical devices. The main result of the analysis is that the received signal analysis should be performed in the reference frame of the receiver; in other words, the received signal should be considered as if the receiver were at rest. In Chapter 3, the true received signal is considered to be random superposition of many wave packets reflected back from targets on the ground. The duration of each wave packet (elementary signal) is equal to the time target being illuminated, and its instantaneous frequency decreases down slowly, as the aircraft progress. The conclusion may be drawn as follows: the true received signal has a broad power spectrum consisting with many line spectrums. The spectrum envelope is stationally and its shape corresponds to the antenna beam pattern, however, the frequency of each line spectrum is slowly shifting in accordance with the instantaneous frequency. Consequently, with a number of targets, the power spectrum is observed to be a continuous one. As yet, more detailed explanation is necessary to explain true situations., 資料番号: SA4135015000},
 pages = {481--509},
 title = {機上ドプラレーダ受信信号について},
 volume = {2},
 year = {1961}
}