Development the Measurement System of the Multi-Channel Frequency Standard Comparison

This paper introduces a measurement system and method of high-speed sampling and full digital for the comparison of multi-channel frequency standard. The hardware of the system consists of 4 parts: A: Impedance matching module (After matching with the impedance of the acquisition circuit, the two input signals are transformed into suitable amplitude, and then transformed into digital signals by the high-speed acquisition circuit). B: High speed data acquisition module. C: Data real-time processing module. D: Calculation module for phase difference and frequency stability. The system not only can achieve real-time processing under the minimum computing resources, but also provide the upper computer with complete information and equivalent frequency data with small amount of data. Moreover, the fast and high-precision calculation of phase difference and frequency stability can be achieved by improving the calculation process. The software of the system meets the requirements for the technical specifications of national metrology. Compared with domestic and foreign frequency standard comparators, the interface of software is more friendly, the operation is more convenient, and it has a strong ability to analyze and process data. The test results show that the uncertainty of the system is better than 1.5 ×10-13 (sampling time is 1 second), which is consistent with Russian VCH-315 index.