Radiofrequency generator and programmer of pulse sequences for PMR relaxometer

Described the generator of resonance radiofrequency with the step of change 50 kHz in the range 520 MHz and pulse programmer of the pulse sequences for relaxometer of proton magnetic resonance (PMR). Using algorithm of direct digital synthesis (DSP), the RF generator has the ability to produce RF signal with a short switching time and high resolution in frequency and phase. To facilitate the generation of RF pulses, used the pulse programmer implemented in the FPGA directed by the auxiliary controller DSP to generate RF pulses with required sequences and parameters. Realized the testing of the generato r by method of computer modelling in the program Quartus II 12.1 and was shown the opportunities of synthesis of RF-pulses sequences with the phases 0, π/2, π, 3π/2 with resonance frequency tuning.

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Design and Implementation of Signal Generator Based on DDS

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.380-384.3643 ◽

2013 ◽

Vol 380-384 ◽

pp. 3643-3647

Author(s):

Hong He ◽

Jin Zhou Zhang ◽

Zhi Hong Zhang

Keyword(s):

Duty Cycle ◽

Pulse Width ◽

Signal Generator ◽

Direct Digital Synthesis ◽

Verilog Hdl ◽

Design And Implementation ◽

Quartus Ii ◽

Digital Synthesis ◽

Frequency Phase

A signal generator with adjustable frequency, phase and duty cycle is designed in this paper. The design of this signal generator is based on the technology of direct digital synthesis (DDS).The classic structure of DDS is presented and its principles are introduced in detail. The key modules of the design such as phase accumulator and pulse width processing are implemented by verilog HDL language. With suitable FPGA, the designed signal generator and all modules of the design are simulated successfully in Quartus II.

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An Improved Doppler Shift Simulation Method Based on Third-Order DDS

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.614.356 ◽

2014 ◽

Vol 614 ◽

pp. 356-362 ◽

Cited By ~ 1

Author(s):

Rui Li ◽

Yuan Long Cai ◽

Xin Bei Bai ◽

Ming Quan Lu

Keyword(s):

Doppler Shift ◽

Dynamic Range ◽

Doppler Frequency ◽

Simulation Method ◽

Global Navigation Satellite Systems ◽

Direct Digital Synthesis ◽

Third Order ◽

Satellite Systems ◽

Digital Synthesis ◽

Global Navigation Satellite

A method to simulate the Doppler frequency shift of high dynamic signals of Global Navigation Satellite Systems (GNSS) is provided in this paper. The methodology of the method based on third-order Direct Digital Synthesis (DDS) is introduced and the efficient implementation architecture is proposed. The design criteria of the DDS are investigated according to the precision and dynamic range of the Doppler shift. The simulation results are also demonstrated, which indicate that the method is available for the high precision Doppler shift simulation of GNSS signals.

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Simulation of Stepped-Frequency LFM Radar Echo Based on FPGA

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.198-199.948 ◽

2012 ◽

Vol 198-199 ◽

pp. 948-953

Author(s):

Jian Ping Ou ◽

Sheng Qi Liu ◽

Wei Niu

Keyword(s):

Moving Target ◽

Direct Digital Synthesis ◽

Implementation Framework ◽

Radar Echoes ◽

Radar Echo ◽

Digital Synthesis ◽

Physical Simulations ◽

Stepped Frequency ◽

Logic Resource

An implementation framework of stepped-frequency LFM (SF-LFM) radar echoes simulator is presented in the paper based on the decomposition and calculation of SF-LFM radar echoes of a moving target. The proposed method can be implemented conveniently with direct digital synthesis (DDS) logic resource. The feasibility of this resolution is verified with computer and semi-physical simulations experiments.

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