A digital instantaneous frequency measurement receiver based on sub-Nyquist sampling

In this paper, sub-Nyquist sampling technology and fast discrete Fourier transform algorithm are applied to the design of instantaneous frequency measurement (IFM) receiver and the structure of the digital IFM receiver based on sub-Nyquist sampling is given. The proposed digital IFM receiver, which is designed with sub-Nyquist sampling technology and fast discrete Fourier transform algorithm, not only reduces the A/D converter and the back-end digital processor requirements and increases the input signal instantaneous bandwidth, but also takes on better real-time quality. Meanwhile, the IFM receiver frequency measurement performance is analyzed in detail and reasons that using sub-Nyquist sampling technology in the digital IFM receiver designed with given structure will not affect its frequency measurement performance are indicated in this paper. In addition, through taking advantage of the two-version signals' amplitude information, the digital IFM receiver designed with the given IFM receiver structure demonstrates better simultaneous signals processing performance. Finally, a simulation with two linear frequency modulation signals coming simultaneously is done and the simulation result verifies the frequency measurement and simultaneous signals processing performance of the IFM receiver designed with given structure. Besides, the simulation result also shows the correctness and feasibility of related design theory and methods.