• 천문학회보
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• 제37권2호
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• pp.228.1-228.1
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• 2012

Digital waveform generation technology for SAR payload can be divided into DDS(Direct Digital Synthesizer) method and Memory Mapped(M/M) method. DDS is the single chip which consists of the Sine Table, NCO(Numerically Controlled Oscillator), DAC, and so on. DDS method is a very simple method because the circuit configuration is not complex but has a disadvantage that can not control phase and amplitude easily by using NCO. M/M method has the complexity of the circuit configuration because it requires the memories which stores the waveforms, the control circuits, and DAC. And this method should apply the high interface technology for being compatible with the wide bandwidth of the digital signal and has the difficulty for PCB design because the number of the signal lines should be increased according to the number of the data bits for DAC. Although it has several disadvantages, this method has the capability of pre-distortion function which can compensate the phase and amplitude characteristics of the system and also has an excellent advantage to make any arbitrary waveform, so this method is considered as an important technology with DDS method. This research describes the technological trends of the waveform generator for the SAR payload and analyzes the characteristics of the technology.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
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• pp.951-954
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• 2001

본 논문에서는 SDR (Software Defined Radio)시스템을 위한 디지털 IF (Intermediate Frequency)수신기를 구현하였다[1][2]. 구현된 수신기의 하드웨어 구조는 AD변환부, PDC(Programmable Down Converter)부, DSP (Digital Signal Processing)부분으로 이루어졌다. AD변환부는 Analog Devices사의 AD6644를 이용하여 아날로그 신호를14bit의 디지털 신호로 변환된다. PDC부분은 Intersil사의 HSP 50214B를 이용하여 14bit 샘플 된 IF(Intermediate Frequency)입력을 혼합기와 NCO(Numerically Controlled Oscillator)에 의해 기저대역으로 다운 시키는 역할을 한다. PDC는 CIC (Cascaded Integrator Comb)필터, Halfband 필터 그리고 프로그램할 수 있는 FIR필터로 구성되어 있다. 그리고 PDC부분을 제어하고 PDC부분에서 처리할 수 없는 캐리어, 심볼 트래킹을 위해 Texas Instrument사의 16비트의 고정소수점 DSP인 TMS320C5416과 Altera사의 FPGA를 사용하였다. 그러므로 중간주파수 대역과 기저대역 간의 신호변환을 디지털 신호처리를 수행함으로써 일반적인 아날로그 처리방식보다 고도의 유연성과 고성능 동작이 가능하고 시간과 환경 변화에 우수한 동작 특성을 제공한다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.44-48
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• 2002

This paper describes an adaptive signal processing of digital receiver with DDC(Digital Down Convertor), DDC is implemented by using NCO(Numerically Controlled Oscillator), digital low pass filter. for the passband sampling, we present the results of digital receiver simulation with DDC. We confirm that the low IP signal is converted to zero IF by DDC. DOA(Direction Of Arrival) estimation technique using MUSIC(Multiple SIgnal Classification) algorithm with high resolution is presented. We Cow that an accurate resolution of DOA depends on the input sampling number.