Research On Signal Sampling And Reconstruction Based On Bandpass Sampling

Software radio is a radio frequency communication technology based on a common hardware platform using software to implement various communication modules.Compared with the traditional single radio function,high development cost and other issues,software can be rebuilt and upgraded to speed up the development of communication modules,reduce development costs,and facilitate debugging and maintenance.In recent years,the improvement of sampling accuracy and rate has promoted the advancement of digital sampling technology,so that band-pass sampling has been widely used in software radio receivers.However,the aliasing of useful signals and image aliasing during bandpass sampling affect the reception of multi-band and multi-mode signals on the same platform.Therefore,it is of great theoretical and application value to study the multi-channel signal and multi-band signal non-aliasing reception in the receiver of software radio.In this paper,based on band-pass sampling,the anti-aliasing technique of the useful signal and multi-band signals in the software radio receiver is studied,and the non-aliasing reception of the band-pass signal is realized.First,in order to solve the aliasing problem of the three-way bandpass signal,a third-order bandpass sampling structure with adjustable delay is proposed.By designing a digital anti-aliasing filter,the three-way bandpass signal can be alias-free receive.The simulation implementation results are given,the signal is reconstructed,and the anti-aliasing performance is analyzed.After the three-channel bandpass signal passes through the anti-aliasing filter,the signal output signal-to-noise ratio can be more than 28 dB.This method solves the problem of multi-signal aliasing in band-pass sampling,increases the sampling frequency selection range,can reduce the hardware burden,and increases the flexibility of software radio.Second,the aliasing of the image limits the flexibility of the bandpass sampling receiver.Aiming at the problem of image aliasing,the second-order bandpass sampling structure is improved,and a simplified gain model is proposed to replace the conventional anti-aliasing filter.The image gain is suppressed by adjusting the complex gain at different positions of the RF signal in the frequency domain.The proposed algorithm is easier to implement,and regardless of the location of the RF signal,it can achieve alias-free reception.The simulation results show that the same receiver can receive the bandpass signal at any position near 0.5-6GHz,and the image aliasing can be suppressed by nearly 30 dB,which improves the receiver's scalability.Finally,in the short-range wireless communication of remote medical monitoring,different medical data measurement devices have different wireless transmission modes.A multi-standard receiver is designed here,which can be adapted to different medical data measuring equipment.Using second-order band-pass sampling to design antialiasing filters can achieve multi-channel signal without aliasing.At the same time,the limitation of sampling frequency is reduced.This design improves the flexibility of the multi-standard receiver in the telemedicine monitoring system and has the advantages of saving spectrum resources and facilitating spectrum planning.