Design of frequency measurement system in external field

The paper proposes the design of frequency measurement system in external field. The system is designed to meet the mobility and integration for complex external field test. The system uses a method of continuous sampling for the frequency difference multiplication. The measurement resolution is improved by using double-balanced mixer to achieve mixing module, filter circuit, and so on. According to the GPIB interface characteristics, D7210C, 75160BN and 75161BN chip are used to complete the task that is bi-directional, asynchronous, accurate and reliable data communications between computer equipment and measuring instruments. The software is designed to complete automatic measurement of atomic frequency in external field. The system meets the test requirements through the data obtained in laboratory and external field. The uncertainty of the system has reached 4E-13.