What is Time and a Half?

The concept of time refers to some definitions of the time system. Including time service system, time zone division and unified time zone system measurement form, measurement method, standard time, etc.

Time concept

Time zones divide 24 areas of the earth's surface into meridians. When we see the sun rise in Shanghai, it will take another half an hour for people living in Singapore to see the sun rise. Residents as far away as London, England, are still sleeping, and it will take another 8 hours to see the sun. People around the world, if they use local time in their lives and work, will cause a lot of inconvenience and difficulties to daily life and transportation. In order to take care of the convenience of use in various regions, it also makes it easy for people in other places to convert the local time to the time in other places. Relevant international conferences have decided to divide the surface of the earth from south to north by longitude and divide them into regions, and stipulate that the time difference between adjacent regions is 1 hour. People at the eastern and western ends of the same area can see the sun rising no more than an hour apart. When people cross an area, they correct their clock for one hour (minus one hour to the west and one hour to the east), and add or subtract a few hours across several areas. This is very convenient to use. There are 24 time zones around the world today. In practice, often one country or one province spans two or more time zones at the same time. In order to take administrative convenience into consideration, one country or one province is often grouped together. So the time zone is not strictly divided by the north-south straight line, but by natural conditions. For example, China has a large territory, spanning almost five time zones, but in fact, only the standard time of the East Eighth Time Zone, that is, Beijing time, prevails.

GMT

Time concept quartz clock

Quartz clock

Quartz clock

A timing device. Everyone is familiar with mentioning the clock. It is a timer that tells us the time. We use it every day. In daily life, a clock of 1 second is enough. But in many areas of scientific research or engineering technology, the hour is much higher. Quartz clocks are created according to this need. Its main component is a very stable quartz oscillator. Take out the oscillation frequency generated by the quartz oscillator. Make it drive the clock to indicate the time. This is the quartz clock. At present, the best quartz clocks are accurate to one hundred thousandth of a second every day. That's about 1 second after almost 270 years. But in today's advanced science, this quartz clock has been replaced by other types of clocks that are much more accurate than it.

Time concept hydrogen clock

Hydrogen clock

Hydrogen clock

A precision timepiece. In many modern scientific laboratories and production departments, various precision clocks are widely used, and hydrogen clocks are one of them. The hydrogen clock is the same as the cesium clock. The electromagnetic wave emitted when the atomic energy level jumps is used to control and calibrate the quartz clock, but it uses hydrogen atoms. The stability of this clock is not much different from that of the cesium clock, which changes by only one billionth of a second per day. In other words, there is only a 1 second difference between almost 3 million years. But its accuracy is slightly worse than that of a cesium clock. Hydrogen clock is also a commonly used time-frequency standard, and is widely used in radio astronomy observation, high-precision time measurement, rocket and missile launch, nuclear submarine navigation and other aspects. The hydrogen clock was first developed for American scientist Ramsay in 1960.

Time concept cesium clock

Cesium clock is a precision timepiece. One minute is enough in daily life. However, in modern social production, scientific research, and national defense construction, the time requirements are much higher. They require time to the nearest thousandth of a second, or even a millionth of a second. In order to meet these high-precision requirements, a series of precise timepieces have been manufactured, and cesium clocks are one of them. Cesium clock is also called "Cesium atomic clock". It uses the electromagnetic waves emitted by the electrons inside the cesium atom to jump between two energy levels as a standard to control the calibration of the electronic oscillator, and then to control the movement of the clock. This kind of clock has a high degree of stability. The best cesium atomic clock is only 1 second after reaching 5 million years. Internationally, the transition frequency of the cesium atomic clock is commonly used as the standard of time frequency, and is widely used in various fields such as astronomy, geodesy, and national defense construction.

Time concept radio clock

About Radio Clock

Radio-controlled timepieces are a new generation of high-tech products after quartz electronic timepieces. Its appearance has opened up new miles for time measurement, made it possible for simple and automatic reception of precise time, and access to ordinary people's homes. Have a significant impact. Countries around the world attach great importance to radio timepieces, and have taken measures to put them into use as soon as possible.

Radio-controlled timepieces have the function structure of receiving radio long-wave signals, data processing, and automatic correction added to quartz electronic timepieces. In this way, they can receive standard time signals sent by ground transmitting stations in long waves. Each radio-controlled timepiece receives this accurate signal. After the time code is processed by the data processor, the travel time error of the quartz electronic clock can be automatically corrected, so that the travel time of each radio clock is controlled by a uniform and accurate time code, thereby realizing the high-precision measurement time and display of all radio clocks. Time consistency.

Development of Radio Clocks Abroad

In the late fifties,

Radio clock

Germany set up a station in Frankfurt, transmitting long-wave time signals with a frequency of 77.5 kHz. The first radio-controlled clock for commercial use was born in 1986. In addition to Frankfurt, Germany and France each set up a long-wave transmitting station, which can broadcast signals covering all of Europe, which creates prerequisites for improving the accuracy of time measurement and time display throughout Europe. The radio-controlled timepieces produced by the German Junghans company have been listed and sold well in the European market. The radio-controlled timepieces have reached 30% of the European watch market. Some developed countries such as the United States, Britain, France, Switzerland, and Japan have established their own launch pads, while the United States and Japan have increased the transmit power of the launch pads several times. Thailand and Malaysia are also considering building long-wave signal broadcasting stations.

The development of Chinese radio clock

The National Time Service Center (Shaanxi Astronomical Observatory) cooperates with related enterprises at home and abroad to promote the development of Chinese radio clocks. Feasibility demonstration was completed in 1994; a test bed capable of working for 5 hours per day (100KW all-solid-state transmitter, transmitting frequency 68.5 kHz) was completed in 1999; trial broadcasting and some external field tests were completed in 2000, which proved that the design was correct; the same year, the development of a receiving chip Success, the radio clock prototype was launched.