A frequency is closely related to the amount of time, commonly referred to as the countdown time, which reflects the meaning of the frequency from the measurement of the cycle time of this fact.
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The salient features of frequency and time are highly sophisticated and highly accurate measurement of the basic definitions, their precision and accuracy measurements improve very fast over the past two decades, far more than all other physical quantities.
Time jargon
World: the earth is converted from a time-mark vengeful, throughout the year the average daily duration of 1/86400, defined as 1s. Because of the Earth's rotation slows down long-term ups and downs and irregular phenomenon, with "seconds" when the world achieve accuracy is not high, only the order of -9 -8 to 10 of 10.
Atomic: intercompany is cesium hyperfine transition radiation is sustained shock 9192631770 weeks time, defined as 1s, energy level transition frequency of the cesium atoms extremely stable, the period of the operation is very accurate and stable . Therefore, since October 1967, the International Meeting adopted the measurement to be defined when the atomic seconds.
When the rotation unevenness due to the Earth, not always accurate atomic 86400 seconds per day, leads to an error of the actual time of about 1s every 18 months world, in order to correct the error decision internationally adopted UTC Times: Coordinated Universal Time . As time standard reusable. That, in seconds, when the atom to time, but when the time difference with astronomical observations to determine the atomic found when more than 0.9 seconds, then at the last second by the end of the year or add a leap second to coordinate, to Coordinated Universal Time when doing a full second adjustment.
Timing: using radio waves to send broadcast standard time signal work called timing, foreign called time service, divided into shortwave granted, when BPL, when the satellite time, when Internet time service and telephone award, etc. Depending on the timing means. The basic method when the timing is short-time broadcasts the radio signal, a radio receiver with a user receiving a signal, then the local pair. Timing using long wave long wave radio signals with the calibration time and frequency transfer, many higher timing accuracy calibration method of surface coverage than the width of the short. Can be achieved when the satellite timing signal coverage large hair broadcast, but compared to when the first two timing methods, higher his accuracy, divided into active and transfer type, an active satellite according to the satellite is the timing in the role of the satellite Granting precision clock, broadcasts the standard time signal, transfer only the transponders standard time signal sent by the ground via satellite ground station time reference, a telephone network timing and timing, using a user mode query standard time information to the user.
Coincides with the timing of time is to make the local timing station broadcasts the standard time. Various methods the timing corresponding to the timing method are: the short timer. Long-wave timing and the timing of the satellite. Since the maximum coverage shortwave numbers. The device is simple, but it is affected by the ionosphere, the timing error of the order of milliseconds. Limited range of applications.
As the number of long-wave propagation delay time is relatively stable. Thus the timer means is a high precision. However, more complex equipment and operations. Satellite Timing and short. Compared to the timing of the long wave. Since the rich time navigation message information. So you can more easily get in. month. Day, hour. Minutes, seconds, etc. Although the information satellite timing of the receiver more complicated, but because of its high degree of integration. Therefore, there is a higher cost, easy to use.
Time product illustration
Time synchronization apparatus using surface mount technology to produce chip control at high speed, no hard disk and fan design, with high accuracy, good stability, function, no accumulation of errors, without geographical climate and other environmental conditions, cost-effective operation simple, maintenance-free characteristics, suitable for unattended.
In the military, too, such as the CEC operations, forward observer radar and missile timing discrepancy itself, the missile will also lead to hundreds of meters of error can not be captured targets. For network-centric warfare, the exact time common standards, is the only means of coordinating the various combat platforms hundreds of kilometers distant, is the cornerstone of network-centric warfare. Briefly, the clock can be used for precise distance measurement, height measurement, synchronization, speed, etc., it is the basic condition tech. for example
Obtaining standard time information from the server on the GPS satellite timing, the TCP / IP network transmission, generating (second signal) information serial synchronizing pulse signal and the time information, minutes and seconds, etc. When the front panel displays information date.
Time synchronization function means
GPS timing signals to establish a reference time; NTP provides an interface path when a feedback network;
Supports standard NTP, SNTP and other network time protocol;
When serial granted, sent once per second, minute, second, year, month, day, time information;
Timing synchronization signal output (1PPS), TTL interface output;
The front panel display date, day, hour, number of teeth and satellite working condition;
Main technical index term frequency standard
The degree of deviation of the actual frequency value and the nominal value of the frequency source output frequency, i.e., characterizing the measured frequency with the standard frequency deviation: frequency accuracy.
Frequency stability: showing the frequency stability of the output clock frequency fluctuation characteristic due to the influence of random noise produced. Frequency stability can be analyzed from the time and frequency domains. Frequency stability is typically characterized by the square root Allan variance.
Frequency offset rate: refers to a linear frequency drift rate of the clock output frequency varies monotonically with time running. With different time units, a Japanese drift rate, monthly and annual rates of drift drift rate. For the quartz crystal oscillator of high stability, since the frequency drift is usually caused by the aging of the quartz crystal, the frequency drift rate so she called frequency aging rate. Atomic clock drift is mainly caused by the internal device. Comprising a frequency drift caused by a quantum structure.
Frequency reproducibility: refers to the frequency reproducibility is twice the standard frequency power, frequency accuracy of the output frequency of the degree of compliance.
Frequency Products
HR series type rubidium atomic frequency standard is a high performance rubidium atomic frequency standard source, imported foreign rubidium atom oscillators with high accuracy, to provide accurate frequency (magnitude) signal, it is possible to provide high measurement, communications, defense and other departments precision frequency standard signal. 4.1 Product Features
It provides one standard 10MHz sinusoidal signal;
Features
Lock fast;
Low phase noise;
High reliability;.
Long-term continuous and stable work.
Conclusion
Standard Specification time is a measure of time: Time lapse speed or time point, or both. Today, only a few had time specification usages and practices have been recognized as the standard. Is used as an example of one application of the time scale is the time standard, which specifies a method for measuring time division. Folk standard time can be defined at the same time interval and time of day.