The time code generator is widely used in smart substations, communication base stations, railway depots and other civilian departments, as well as command posts, technical positions and shooting ranges of military departments, so as to provide users with accurate time signals and ensure time unification among systems. This article will briefly introduce the timing principle of the B code generator and the related equipment needed in the calibration process.

The time code generator is composed of a standard time signal receiving unit, a time holding unit and a standard time frequency signal generating unit. By receiving time information such as GPS, BD, GLONASS and other satellite signals or B (AC) and B (DC) code, the local clock is synchronized, and time is maintained by using the internal time base, and 1PPS, B (AC) code, B (AC) code, time signal and standard frequency signal are exported externally.

The specific characteristics of the time code generator refer to the technical requirements of the time code generator and refer to the requirements of the metrological characteristics of the time code generator calibration specification (Draft).

The whole calibration process needs to be completed in the environment where mechanical vibration and electromagnetic interference do not affect the normal operation of the equipment. The measuring standard and other equipment used include reference time source, reference frequency source, time interval counter, time code meter, frequency counter, frequency difference multiplier, phase comparator, frequency comparator and frequency divider. Of course, these calibration conditions are general requirements to be followed in calibration, and reasonable changes can be made in practical applications. The time code generator calibration method can be referred to the steps in the calibration specification. In this article, we will briefly introduce the calibration method of B (DC).

How does the signal output B (DC) of the time code generator calibrate the deviation relative to the standard time? First, the calibration system is connected with the chart. According to the preheating of the instructions, when the satellite is locked, the output of the B (DC) code is connected to the input terminal of the time code tester. After measuring the 1H, the measurement error of the B code synchronous deviation is calculated.

The reference time source and time code measuring instrument in the measuring equipment can use SYN5104 type equipment at the same time. Output high precision time information of various signal formats as reference time source. As a high standard, the time code tester is used to measure the errors of 1PPS, B code and NTP.

The reference frequency source can be supplied with SYN3204 rubidium frequency standard, which can meet the stipulation of the reference frequency source in the calibration code for time code generator (Draft), and provide high-precision time and frequency standards for measuring and testing units, to some extent, it can be used as a measuring instrument instead of cesium clock. At the same time, the rubidium frequency standard has passed the verification of the national defense science and technology industrial laboratory.

The SYN5609 type is used as the frequency comparator in the calibration equipment. It tests the short stability and frequency accuracy of the input frequency standard signal, and the measurement algorithm and data processing fully comply with the requirements of the national verification regulation for the related frequency standard characteristics testing.