Papers by Keyword: DDC

Abstract: The theory of down sampling technique base on band-pass sampling and using inSoftware radio is introduced in this paper. We provided an achievement method ofNumerically controlled oscillator (NCO) in digital down converter of down samplingtechnique in the article.

Abstract: Multi-frequency receivers rely on GNSS to achieve high-precision positioning, high sensitivity and other functions. GNSS signal frequencies are widely distributed around 1.1GHz to 1.6GHz. Good performance RF front-end receiver will provide high-quality acquisition and tracking environment, reducing the SER to ensure CNR. RF sampling technique is widely used in software radio for its simple structure, flexible configuration, and other advantages, but rarely used in satellite navigation, because the high signal carrier frequency and sampling rate, down-conversion based on RF sampling becomes a big challenge. So, to solve the problems of widely distributed we design three signal bands, using different local oscillator to implement signal down-conversion; to solve the problems of high sampling rate, we propose a down-conversion program of using a cascade of CIC filter’s ployphase and FIR compensation filter. Through the simulation of MATLAB after tracking tests, analysis of CNR and other indicators of programs. Ultimately, we implement the program with Verilog language on the multi-frequency GNSS receiver. The results show that this scheme can achieve digital down-conversion and stable performance of tracking loop with less consumption of resources.

Abstract: In the boiler heating control device of combining DDC and the silicon controlled rectifier voltage regulation device, there are phase shift trigger, pulse width modulation (PWM) and cycle wave cross zero trigger (CYC). Under the different silicon controlled rectifier voltage regulation devices, there are different influences for DDC. It makes the best of the cycle characteristics of the alternating current (AC) for the cycle wave cross zero trigger (CYC). For DDC - temperature control system, there are advantages of high control accuracy, less interference and power source pollution.

Abstract: Digital down converter (DDC) is based on the theory of Software Defined Radio (SDR) and multirate signal processing, extensively applied in digital receivers of communications systems. An improved resource-efficient DDC with polyphase architecture and distributed arithmetic (DA) is presented in this paper. The design based on Xilinx FPGA Virtex-5 has more flexible characters and higher precision computation with less resource consumption.