This standard specifies the broadcast time signal. This standard applies to the broadcast time signal system of radio stations. GB/T 4961-1999 Broadcast Time Signal GB/T4961-1999 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
GB/T 4961—1999
Time signal in radiobroadcastingPublished on October 10, 1999
Implemented on January 1, 2000
State Administration of Quality and Technical Supervision
GB/T4961—1999
This standard is a revision of the original GB/T4961—1985 "Time signal in radiobroadcasting". With the development and progress of science and technology, the time signal in radiobroadcasting has gradually evolved from the original single function of telling the audience the time to an indispensable part of the national economic development process. It increasingly provides standard clock signals for scientific research, military, medical, and social and economic activities, especially for people in field operations, military, navigation, and remote areas to provide accurate time. As people's living standards continue to improve, people's pace of life gradually accelerates, and the length of the original broadcast time signal can no longer meet the needs. Therefore, the length of the time signal is revised from the original 10s to 5s.
Due to the rapid development of digital technology in my country, the production, broadcasting and transmission of radio programs have gradually developed from the original analog mode to the digital mode. It has become possible and necessary to add time code signals to the broadcast time signal. In order to meet the needs of national defense and social and economic development, field workers and listeners in remote areas should be allowed to listen to and measure accurate time signals and time signals with year, month, day and time. By adding the transmission time code to the time signal, the audience can not only receive the hourly time signal, but also automatically calibrate the time by receiving the transmission time code, so as to better serve scientific research and production, and better serve people's daily life. Based on theoretical analysis and experiments, combined with the actual situation of my country's broadcasting system and the needs of listeners to listen to broadcast time signals, and considering the international standards, this drafting group revised GB/T4961-1985. The main changes are as follows: 1 The scope of application of the original GB/T4961-1985 is that this standard applies to the broadcast time signal system of the Central People's Broadcasting Station, which is revised to: This standard specifies the broadcast time signal. This standard applies to the broadcast time signal system of radio stations. 2 In the basic requirements, the time format of the original 1.3 signal is changed to: (1) In order to adapt to the fast-paced life of modern society and the requirements of the audience, and to improve the role of broadcast time signals in the development of the national economy, the interval between each ring is revised from 2s to 1s based on a large number of experiments. The interval between the first ring and the last ring is revised from 10s to 5s.
(2) In order to retain the characteristics of my country's broadcast time signal and take into account the international standards, the duration of each of the first 5 ring signals is revised from 0.5s to 0.25s.
(3) The starting time of the first ring is revised from 59min50s to 59min55s. The leading edge of the starting time of the last ring is the hour. (4) The original 1.3.1 bass and treble signal error is better than 0.01s, revised to: 2.3.1 bass duration is 0.25s, treble duration is 0.5s, and the allowable error of duration is ±0.001s. (5) The original 1.3.2 interval between two sounds is 2s, the error is better than 0.1s, revised to: 2.3.2 interval between two sounds is 1s, the allowable error is ±0.001s.
After the modification, the following results are obtained:
(1) The time signal time is shortened from 10s to 5s, which shortens the time and increases the program time. (2) Shortening the time has no adverse effect on the program. (3) The time signal length is shortened from 0.5s to 0.25s, and the signal duty cycle is still the same as before the signal is shortened, which is easy for the audience to accept. This modification is feasible.
3 added 2.4.2 The accuracy of the local radio station's hourly time is better than 5/100s. 4 Add 2.5 time code.
Appendix A of this standard is the appendix of the standard.
This standard was proposed by the former Ministry of Radio, Film and Television of the People's Republic of China. This standard is under the jurisdiction of the Standardization Planning Institute of the State Administration of Radio, Film and Television of the People's Republic of China. The drafting units of this standard: China Radio International, China National Radio, Qingdao Radio and Television Science Research Institute, Harbin Zhengda 1
GB/T4961—1999
Electronic Engineering Company.
Main drafters of this standard: Wang Zexiang, Ouyang Ming, Sui Zhiguo, Xu Zhengzhong, Wei Minhua. 2
1 Scope of application
National Standard of the People's Republic of China
Time signal in radio obroadcasting
Timesignal in radio obroadcasting This standard specifies the time signal in radio obroadcasting.
This standard applies to the time signal system of radio stations. 2 Basic requirements
2.1 Time reporting method
GB/T4961-1999
Replaces GB/T4961-1985
Five bass sounds are reported before every hour, and one treble sound is reported at the hour, and the starting point of the treble sound is regarded as the hour. 2.2 Signal frequency
The frequency of the bass signal is 800Hz, with an allowable error of ±0.8Hz, and the frequency of the treble signal is 1600Hz, with an allowable error of ±1.6Hz. 2.3 Signal time format
See Figure 1.
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2.3.1 The duration of the bass signal is 0.25s, and the duration of the treble signal is 0.5s. The allowable error of the duration is ±0.001s. See Figure 2. C-
2.3.2 The interval between each two sounds is 1s, and the permissible error is ±0.001s. See Figure 3. Approved by the State Administration of Quality and Technical Supervision on October 10, 19995:
Implemented on January 1, 2000
2.4 Accuracy of hourly time announcementbZxz.net
GB/T4961—1999
Starting point·
2.4.1 The accuracy of the Central People's Broadcasting Station's hourly time announcement is better than 1/100s. 2.4.2 The accuracy of the hourly time announcement of local radio stations is better than 5/100s. 2.5 Time code
The order of time code is: year, month, day, and time.
The format and parameters of the time code are to be determined.
GB/T4961—1999
Appendix A
(Appendix to the standard)
Technical requirements for broadcast timekeeping equipment
The equipment must be equipped with a comparison device with an accuracy better than 1/1000s. Al
The daily aging rate of the crystal oscillator is <3×10-8. The equipment must be equipped with a display device for the time difference between the local clock and the reference clock. The signal-to-noise ratio is better than 80dB.
The output mode is balanced output, and its output amplitude is 1.5V (effective value). 3
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