System Design of a Hyperspectral Microwave Radiometer Intermediate Frequency Module

Abstract

In this article, the system design of the IF (Intermediate Frequency) module which is a crucial component of hyperspectral microwave radiometers is introduced. The IF module consists of 6.4GSPS sampling-rate ADC (Analog-To-Digital Convert) and Virtex-7 FPGA (Field Programmable Gate Array). The module is a real-time system with a frequency bandwidth of 3.2GHz and a spectral resolution of 6.25MHz. The 1024-point FFT (Fast Fourier Transform) algorithm which takes 160ns to accomplish an entire calculation is implemented in an FPGA. The effective number of channels of this module is 512 because of the symmetry conjugate of the FFT output. The test results of this module are given and analyzed, including the system response of deterministic signals and stochastic signals. The linearity of this module is also measured with the correlation coefficient which is up to 0.9999. The IF module can be widely used in hyperspectral microwave radiometers in various applications.