This paper is a patent document designed by Xi 'an * * * Company for national radio timing, which has not been published.
Abstract: The invention relates to radio wave timing coding. Characterized in that:
The frame period is 20 seconds, and each minute contains three frames;
The second pulse width represents 0, 1, 2, 3 of the quaternary number, and the corresponding time information such as minute, hour, day, month, year and week is represented by the quaternary number;
The frame mark is used to indicate the time period of the frame, and the missing second pulse is used as the frame interval and frame preview mark;
Code bit multiplexing technology is adopted.
The invention overcomes the shortcoming that the existing time coding frame period is too long, and the shortest time for receiving a frame of time information is reduced from 1 minute to 20 seconds, thus improving the efficiency of the receiver and reducing the anti-interference requirements.
Interpretation of nouns and terms:
Time coding: digital pulse signals are used to encode time information such as minutes, hours, days, months, years and weeks.
Square wave second pulse: the waveform of digital pulse signal is square wave, and its period is 1 second.
Frame (i.e. time information frame): a group of codes (or codes) containing time information such as minutes, hours, days, months, years and weeks, and necessary check marks.
Frame period: the time from the beginning of one frame to the beginning of the next.
Background art:
Radio timing refers to the accurate time information derived from high-precision atomic clock, which is transmitted by radio transmitter with low frequency (20kHz- 100kHz) radio waves. The user receives the signal through the radio receiver, demodulates it to recover the time code, and then the code is processed (decoded) by the microprocessor to obtain accurate time information. At present, in Germany, the United States, Britain, Japan and other countries, radio time service has been widely used in electric power, communications, civil aviation, railways, personal watches and other fields.
Time coding used in radio wave timing is an important factor affecting the accuracy and reliability of time information dissemination and the manufacturing technology of transmitting and receiving equipment. The existing time codes are DCF (Germany), MDF (UK), WWVB (USA), JJY/JG2AS (Japan) and so on. The common characteristics of these time codes are: forming time codes with square-wave second pulses; The pulse leading edge marks the beginning of 1 sec. Binary number 1 or 0 is represented by different pulse widths (i.e. the duration of square wave pulse signal), and binary number represents time information such as minutes, hours, days, months, years, weeks, 1 min.
Due to the inevitable interference in the process of radio wave propagation, information distortion, error code and missing code are all possible. Although the necessary parity bits are set in the existing time coding to judge the correctness of the received information, this simple verification method still has a high misjudgment rate. An effective method, which is also widely used at present, is to check each group of codes with check codes when receiving signals, and then make a final judgment after comparing two or three frames of information received continuously. Therefore, it takes at least two to three minutes to receive a complete and accurate set of time-coded information. This not only makes the efficiency of the receiver very low, but also makes it difficult or even impossible to receive the signal when the interference is serious, especially when the signal is weak or sometimes there is no signal at the distant transmitting place.
Summary:
The purpose of the invention is to overcome the defect that the existing time coding frame period is too long, so as to improve the efficiency of the receiver and reduce the influence of interference or weak signals on the received information.
The technical scheme adopted by the invention is as follows:
1. Time coding is formed in the form of square wave second pulse, which does not reduce the frame information capacity of the existing time coding and shortens the frame period to 20 seconds;
2. Each minute contains three frames, and each minute is divided into three time intervals (0 to 19 seconds, 20 to 39 seconds, and 40 to 59 seconds), so that each frame occupies a time period;
3. The frame mark indicates the time period in which the frame is located;
4. The second pulse width of each square wave is represented by different second pulse widths as quaternary numbers 0, 1, 2, 3, and the corresponding time information such as minutes, hours, days, months, years and weeks is represented by quaternary numbers;
5. Taking the lost second pulse as the frame interval and the frame preview sign, two check codes are added to each frame, and the value of the code received before each check code is converted into "1" after the binary expression, and the numbers are configured as even and odd numbers;
6. Give a code two or more meanings by using four possible values of the code (called "code reuse").
The invention has the advantages that the shortest time for receiving one frame of time information is reduced from 1 minute to 20 seconds, and the shortest time for detecting errors by using the comparison results of three frames is reduced from 3 minutes to 1 minute, so that the receiver efficiency is improved, the countermeasure requirement is reduced, and it is possible to receive the time information when the signal is far away from the transmitting station. At the same time, the code is still encoded in the form of second pulse, which is compatible with the existing time code, so the signal reception does not need an expensive special receiving system, and the time service signal can be reliably received by using the existing time code receiving chip and mature decoding technology. It is beneficial to the popularization, application and accelerated development of radio timing technology in China.