Design of Automatic Test System for Multi-channel Digital Receiver Module

To achieve miniaturization and function integration of the telemetry radar antenna, multi-channel analog and digital circuits are integrated into a single receiver unit called Digital Receiver Module (DRM). To fulfill the real-time transmission of baseband data, optical fiber is applied as the transmission medium. The above two points make it impossible to measure key indicators of DRM rely only on traditional microwave instruments. Automatic Test System (ATS) based on LXI architecture with functions of command sending, baseband data receiving and instrument control is designed as a solution. Multi-channel signal routing link is established by dividers and microwave switches, so that all channels of DRM can be tested in parallel. Optical fiber transceiver is exploited not only to send synchronous commands, but also to receive and record baseband data. Signal processing methods dedicated to the specific characters of DRM are designed to analyze key indicators from baseband data, such as receiving gain, noise figure and instantaneous dynamic range. Automatic test software and signal processing methods are implemented using VS2005. Through practical application, the obtained results are completely consistent with the design baseline. Besides, on the premise that communication interference and temperature change are included in the test results, the maximum deviation of receiving gain is ±0.21dB and the maximum deviation of noise figure is ±0.23dB within five discrete measurements, which could demonstrate the accuracy and effectiveness of the ATS.