GPS Timing Explorer (GPS satellite time is) commonly used in synchronous mode
GPS Timing Explorer (GPS satellite time is) commonly used in synchronous mode
GPS time is by the Anhui Beijing-Technology developed a high-tech products
Satellite timing when the timing is sent to the multicast or broadcast standard time signal by means of satellite navigation. With low-cost timing, high precision, simple and so widely used.
The commonly used navigation satellites have China's Beidou navigation system and the US GPS. When satellite timing and location are combined, the average user can be realized obtaining precision timing on the basis of their accurate positioning.
GPS satellite timing generally by the antenna, the radio frequency unit, a signal processing unit, a data processing unit and the output interface unit.
When the current GPS satellite has granted more time passes the time synchronization interface standard. For wide-area distributed network, using the satellite receiver to get standard time award, this time needs to be issued to each part of the system.
Common time synchronization interface time code, the time code, such as a typical IRIG-B code, there is division of the DC code and AC codes. Code alternating (AC) signal is modulated, transmission distance. Be used within a short distance to the time message interfaces, RS232 serial port through the delivery time. Fiber than from electromagnetic interference, the current time has become a popular means of communication.
NTP network time synchronization using time synchronization protocol to achieve network computer, now more widely used. Determine the number of outlets as the clock source site, in order to achieve time synchronization to UTC time, to provide users with a unified, standard delivery service through the network. The complexity of the synchronization time on the Internet, this time in the NTP protocol designed to take into account the very beginning, to do a special deal. So now in effect at the time under actual application case clock source can be implemented to correct track of time, if the case of network failure is still able to maintain a stable time. Ensure that the network remains at a precise time synchronization within a certain time, so using UDP / IP based NTP mechanism of hierarchical time distribution model to meet different Internet environment. Recommended gps satellite time service is HR-901GB model type.
With the improvement of the accuracy of time synchronization, ntp network time granted ms accuracy in many areas higher level synchronization accuracy has been unable to meet demand. IEEE 1588 PTP this case by many users concerned, PTP stands for "Precision Measurement and Control System network clock synchronization protocol standards." HR-901GB IEEE1588 type to the master clock as an example, PTP high timing accuracy can be achieved but there must ns level supporting hardware required can only be used with the master. ptp protocol when there are two ways of, one is mac, one is udp mode, the precision is the same, the common mode udp.
Refers to the time message the time information extracted by the timing correcting device after receiving the reference time information in the source and format of the output of the time constant. E.g. HR-906C-GPS timing Compass navigation receiver, time message typically used together in conjunction with the second pulse, the principle shown in FIG its timing, the output message information in general within a certain time interval after the second pulses, packets message contains the time in seconds corresponding to the pulse rise time is generally less than 5ns second pulse, using a second rising edge of the pulse may provide precision timing accuracy level of several ns.
At present time packet NEMA protocol most widely used, NEMA protocol time-related commands are mainly GGA, GLL, RMC commands.
