Bezpośrednia cyfrowa synteza częstotliwości realizowana dla potrzeb techniki radarowej

• Autorzy: Olech B.

Warianty tytułu

EN

Direct Digital Synthesis (DDS) for radar applications

• Języki publikacji: PL

Abstrakty

PL

Bezpośrednia synteza cyfrowa częstotliwości (DDS) jest wykorzystywana w radarach niemal zawsze, jeśli wymagane są: duża rozdzielczość nastawy częstotliwości (poziom Hz i mniej) i duża prędkość przełączania (mniej niż 1 žs). Synteza taka zapewnia bardzo dobry poziom szumów fazowych, małą niestałości przełączania (jitter) oraz ciągłość fazową przełączania, jednak generuje bliskie harmoniczne. W artykule przedstawione zostało porównanie standardowych rozwiązań DDS na tle realizacji z użyciem FPGA.

EN

Direct Digital Synthesis (DDS) is widely used in radar systems when high resolution frequency setting is the must (1 Hz or less). And, when modulation scheme of Continuous Wave (CW) radar requires fast changing in shape, or switching (1 žs or less) the frequency. DDS is less power consuming and more compact in hardware than direct analog synthesis. DDS preserves or even enhances noise level of the source clock, guarantees phase continuity during switching. The main disadvantage of DDS is the spurious level generated as the result of angle discrete integration in time and discrete voltage levels of the output periodic signal. Another disadvantage is the limited bandwidth of a few hundreds of MHz. In this paper a few standard DDS chips are presented. Examples are representative for high quality and high speed demands. Since FPGA technology covered a great piece of digital applications, it is also often used in radar technology. Apart from fast and parallel DSP applications, FPGA can generate arbitrary modulated CW signals. However, FPGA works with lower clocks than standard (or ASIC) chips, it further limits the bandwidth available. But because of the FPGA re configurability, some dedicated improvements for spurious reduction are available. This makes FPGA the attractive solution, making also system on chip integration possible. For these reasons, in this paper an example of FPGA implemented DDS is analyzed too, giving a reference in relation to the standard solutions.

Słowa kluczowe

PL

bezpośrednia synteza częstotliwości; reprogramowalne tablice logiczne; radar

EN

DDS; FPGA; radar

• Wydawca: Wydawnictwo PAK
• Czasopismo: Pomiary Automatyka Kontrola
• Rocznik: 2012
• Tom: R. 58, nr 7
• Strony: 572--574
• Opis fizyczny: Bibliogr. 9 poz., rys., tab., wzory

Twórcy

autor

Olech B.

• Zachodniopomorski Uniwersytet Technologiczny w Szczecinie, Wydział Informatyki, ul. Żołnierska 47, 72-210 Szczecin,

Bibliografia

• [1] Stavenick Peter: Synthesizers Offer Submicrosecond Switching, Microwaves & RF, No. 51, pp. 98-102, June 2002.
• [2] Chenakin Alexander: Frequency Synthesizers Concept to Products, Artech House, Inc., ISBN 13: 978-1-59693-230-2, 2011.
• [3] Khitrovskiy V. A.: Circuitry and Technological Aspects of Frequency Synthesizers Design for Modern Radars, MSMW’O4 Symposium Proceedings. Kharkov, Ukraine, June 21-26, 2004.
• [4] Kroupa Venceslav F.: Phase and Amplitude Disturbances in Direct Digital Frequency Synthesizers, IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, Vol. 46, No. 3, pp. 481-486, May 1999.
• [5] Cushing Rick: Single-Sideband Upconversion of Quadrature DDS Signals to the 800-to-2500-MHz Band, Analog Dialogue 34-3, 2000.
• [6] Chao Huang, Li-xiang Ren, Er-ke Mao, Pei-kun He: A Systematic Frequency Planning Method in Direct Digital Synthesizer (DDS) Design, Wireless Communications & Signal Processing, 2009. WCSP 2009. International Conference on, pp. 1-4, 13-15 Nov 2009.
• [7] Flanagan Michael J. and Zimmerman George A.: Spur-Reduced Digital Sinusoid Synthesis, IEEE Transactions on Communications, Vol. 43, No. 7, pp. 2254-2262, July 1995.
• [8] Omran Hesham, Sharaf Khaled and Ibrahim Magdy: An All-Digital Direct Digital Synthesizer Fully Implemented on FPGA, Design and Test Workshop (IDT), 2009 4th International, pp. 1-6, 2009.
• [9] Analog Devices, Inc., A Technical Tutorial on Digital Signal Synthesis, 1999.