An adaptive delay calibration method for optical beamforming networks (OBFN) based on wideband sweep and windowed FFT spectrum analysis is proposed and demonstrated by simulation. With the FFT spectrum analysis of the wideband sweep signal, the delay difference between different channels in OBFN can be obtained continuously, and can be canceled adaptively by controlling variable optical delay lines(VODL), resulting in fast and high precision calibration for an OBFN. Furthermore, assisted by pilot carriers with multiple frequencies, the phase unwrapping can be achieved, and phase difference beyond 2π can be compensated. In order to demonstrate such method, a 16-arrayoptical beamforming simulation system is presented in this paper. Simulation results show that delay calibration range reaches467.1ps with the frequency range of 6-18 GHz. The delay calibration accuracy is increased by 50 times from5ps to 0.1ps. In addition, the number of simultaneous beamformer achieves to be 3, which covers the airspace from-30° to +30°.
KEYWORDS: Microwave photonics, Computer simulations, Computing systems, Data modeling, Digital signal processing, Microwave radiation, Radar signal processing, Antennas, Parallel computing
Due to the difficulty in simulation for massive array microwave photonics systems, a distributed cross-domain parallel simulation method is proposed in this paper. Firstly, the link parallel computation across system structural domains is achieved based on the independent transmission between channels for each array element in the microwave photonics system. Secondly, the data parallel computing across time domains is achieved by utilizing the relative independence between the pre and post processing times. Furthermore, assisting by a static load balancing strategy to allocate computational resources, these two approaches are effectively combined to achieve high efficient simulation of the microwave photonics system, which addresses the issue of long simulation time caused by large amounts of data and models. For a microwave photonics system with a 64-array and more than 400 models, this technique reduces the simulation time from 39 hours to 23 minutes, resulting in a simulation efficiency improvement of two orders of magnitude. This advancement holds the potential to significantly shorten the development cycle of microwave photonics engineering prototypes.
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