Multi-Standard Digital Baseband Signal Generate Technology

Baseband signal generator is an important component of vector signal generator. On the one hand, baseband signal generator provides the required modulated baseband signal for I / Q modulator. On the other hand, baseband signal generator generates baseband signal can be used as the output signal, direct output to the rear panel, to provide users with a variety of simulation test function. However, with the continuous development of digital modulation techniques, the original base-band signal generator performance more difficult to meet the growing needs of the user. Therefore, it is necessary to restart the research on baseband signal generator to meet the requirements of the new generation vector signal generator. Makes the baseband signal generator to provide multi-format, high bandwidth digital modulated baseband signalThis paper discusses the theories and the principles of generating I/Q baseband signal of various digital communication systems in detail, which is used in the baseband signal generator designing. For this, it was created a general, standard and modular hardware platform based on the ?eld-programmable gate array (FPGA) with embedded software-core processor and realized the radio function by software instead of hardware. On the basis of this, FSK, PSK and QAM modulation signals have been designed and realized by using reconfigurable technology of FPGA and advanced EDA tools. At the same time, the emphasis of the paper is put on the study of design and FPGA Implementation the pseudorandom sequence construction method, code map, digital pulse-shaping filters, cascaded integrator-comb filter and direct digital synthesizer. Build the test platform, analysis the modulated signal. The application and the test result shows that the quality of signal is well, which can meet common electronic measurement and test requirements. The paper achieved the following key findings:(1)The multi-standard programmable digital baseband signal generate technology based on FPGA was proposed, which can generate FSK, MSK, GMSK, BPSK,QPSK,8PSK, OPSK, DPSK, QAM16, QAM64, QAM128 and QAM256 modulation signals;(2) The digital baseband signal source was designed to generate ALL1s, ALL0s, PN9, PN13, PN15, PN23 and user-defined baseband signal.(3)Designed multi-standard FIR digital filters for baseband signal filtered, which is realized by using FPGA. The filter's parameters can be changed by software, so it can realize lots of filters, such as Gaussian, Nyquist, Root-Nyquist and rectangular.(4) Depth study of issues related to multi-rate signal processing in baseband signal generator. The variable interpolation filter group was designed to achieve a wide range of symbol rate, the symbol rate from 1KSym / s to 50MSym / s.