徑向速度對頻率步進(jìn)雷達(dá)目標(biāo)距離像影響分析
Analysis of radial velocity effect on range profile of stepped-frequency waveform
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摘要: 脈間頻率步進(jìn)波形是一種高距離分辨率信號形式,它通過子脈沖載頻的步進(jìn)變化來獲得大的有效帶寬,顯著降低了系統(tǒng)的瞬時帶寬和對接收機(jī)硬件的要求。但該信號對目標(biāo)徑向速度非常敏感,雷達(dá)與目標(biāo)間的徑向運(yùn)動將造成距離像峰值的移動、衰減和發(fā)散。該文深入分析了目標(biāo)徑向速度對頻率步進(jìn)雷達(dá)一維合成距離像的影響,推導(dǎo)出不同距離取樣分辨率條件下的距離像偏移因子和發(fā)散因子表達(dá)式。通過對復(fù)數(shù)距離像相位的分析,證明了采用補(bǔ)零法來增加逆傅里葉交換點(diǎn)數(shù)只能提高距離取樣分辨率,而不會影響雷達(dá)的距離分辨率。Abstract: Stepped-frequency is a kind of high range resolution waveform, which is used to obtain broad effective bandwidth by sequentially changing of carrier frequency over sub-pulses in one burst, so it reduces requirements on instantaneous bandwidth and receiver. However, this waveform is so sensitive to radial velocity between radar and targets that the loss of range resolution and loss of SNR are brought to SAR system. In the paper, the effect of radial velocity on synthetic range profile is discussed thoroughly first, then two important parameters, target range shift and range spread, are defined in terms of the phase of synthetic range function. Furthermore, the enhancement of the range sample resolution only makes the synthetic range profile present more details, but it will not change the range resolution.
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D.R. Wehner, High Resolution Radar (2nd ed), London, Artech House, 1994, Chaper5.[2]R.T. Lord, M. R. Inggs, High resolution VHF SAR processing using synthetic range profiling.Proc. IEEE Geoscience Remote Sensing Symp., IGARSS96, Lincoln, Nebraska, June 1996, vol.1.454-456.[3]G.S. Gill, Step frequency waveform design and processing for detection of moving targets in clutter, IEEE International Radar Conference, Washington D. C., May 1995, 573-578.[4]安建平,張潤寧,白克壯,應(yīng)用于SAR的一種波形及多普勒效應(yīng)補(bǔ)償技術(shù),系統(tǒng)工程與電子技術(shù),2000,22(1),59-62.[5]K. Ruttenberg, et al., High range resolution by means of pulse to pulse frequency shifting, EASCON68 Record, Washington D. C., Sep. 1968, 47-51.[6]張澄波,綜合孔徑雷達(dá)原理、系統(tǒng)分析與應(yīng)用,北京,科學(xué)出版社,1989,30-33.[7]吳湘淇,信號、系統(tǒng)與信號處理(上),北京,電子工業(yè)出版社,1996,118-122. -
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