کاهش کلاتر برد-دوپلر با فیلتر فشرده سازی پالس وفقی به وسیله شکل موج فرکانس پله ای تصادفی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده مهندسی برق - دانشگاه جامع امام حسین (ع) - تهران - ایران

2 شرکت مهندسی محققان یاسین - تهران - ایران

3 دانشکده مهندسی برق و ارتباطات - دانشگاه جامع امام حسین (ع) - تهران - ایران

چکیده

در رادارهای پالس دوپلر معمولاً از فشرده‌سازی پالس و روش پردازش دوپلر برای آشکارسازی هدف متحرک از طریق تبدیل فوریه سریع استفاده می‌کنند. روش فشرده‌سازی پالس متعارف و خروجی فیلتر منطبق استاندارد برای آشکارسازی اهداف کوچک نزدیک به یک هدف بزرگ کارایی مناسبی ندارد، زیرا گلبرگ‌های جانبی خروجیِ فیلتر منطبقِ هدف بزرگ، باعث ماسک شدگی اهداف کوچک می‌شود. فشرده‌سازی پالس وفقی این مشکل را به‌طور قابل‌توجهی در نویز رفع می‌کند. اما هدف سریع یک شیفت فاز دوپلر به فرکانس سیگنال دریافتی القاء می‌کند که باعث عدم تطابق سیگنال دریافتی و سیگنال ارسالی می‌شود. درنتیجه نسبت توان سیگنال به نویز کاهش می‌یابد. از آنجائی که فیلتر منطبق در گیرنده رادار فقط با نسخه سیگنال ارسالی تطبیق دارد، به دلیل عدم تطبیق با سیگنال دریافتی از محیط، خروجی آن دچار تلف می‌شود. معمولاً فشرده‌سازی پالس وفقی در محیط صرفاً نویزی با یک تک پالس قابل‌اجرا است اما در حضور کلاتر قوی به چند پالس برگشتی از هدف نیاز دارد. در این مقاله برای تأمین این پالس‌ها، در فرستنده رادار مجهز به فشرده‌سازی پالس وفقی، شکل‌موج‌های متنوع به‌وسیله پرش فرکانسی تصادفی در شکل‌موج فرکانس پله‌ای (شکل‌موج فرکانس پله‌ای تصادفی) تولید می‌شود. با این روش اهداف ماسک شده در مجاورت یک هدف قوی و کلاتر با روش پیشنهادی آشکار می‌شود. نتایج شبیه‌سازی آشکارسازی اهداف متحرک ماسک شده با سایر روش‌های متداول مقایسه و بررسی می‌گردد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Range-Doppler Clutter Suppression with Adaptive Pulse Compression by Randomized Stepped Frequency Waveform

نویسندگان [English]

  • Reza Kayvan Shokooh 1
  • Alireza Zakeri 2
  • Younes Mohammadi 3
1 Faculty of Electrical and Communication, University of Imam Hossein, Tehran, Iran
2 Yasin Engineering Company, Tehran, Iran
3 Faculty of Electrical and Communication Engineering, University of Imam Hossein, Tehran, Iran
چکیده [English]

Pulse-Doppler radars typically use pulse compression and Doppler processing to detect moving targets through fast Fourier transforms. The conventional pulse compression method and the standard matched filter output for detection of small targets close to a large target do not work well, since the sidelobes of the match filter output by a large target could mask the smaller targets. Adaptive pulse compression resolves this issue significantly in noise. However, the fast targets induce Doppler phase shift in the received signal frequency, in which cause mismatch between the received signal and the transmitted signal. Consequently, the Signal to Noise Ratio is reduced. Whereas the matched filter in the radar receiver is only adapted to the transmitted signal version and its output will be wasted due to non-matching with the received signal from the environment. Adaptive pulse compression is generally applied with a single pulse in alone noise environment, but in the presence of strong clutter it is required to several return pulses. In this paper, to supply these pulses, in a radar transmitter equipped with adaptive pulse compression, waveforms diversity are generated by random frequency hopping in step frequency waveform. The simulation results of the detection of masked moving targets are compared with other conventional methods.

کلیدواژه‌ها [English]

  • Adaptive Pulse Compression
  • Waveform Diversity
  • Pulse Doppler
  • clutter
  • Randomized Stepped Frequency Modulation
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