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How is a PPS signal generated?
The Pulse Per Second (PPS) signal generated by a GPS receiver is used for the synchronization between separate stations in the communications system or the measurement system. A commonplace single frequency GPS receiver contains a temperature-controlled crystal oscillator (TCXO) which oscillates at about 16MHz.
What are the services of GPS?
GPS provides two different positioning services: the Precise Positioning Service (PPS) and the Standard Positioning Service (SPS).
How to know the time of the PPS signal?
If you need to know the time of the PPS, you need to latch an internal timer when the PPS signal occurs, then associate that with the data from the GPS when it comes in. Alternatively, keep track of the GPS data and, when the PPS is asserted, you can assume that it is now most_recent_gps_time_utc + 1 second.
Why do GPS receivers have a 1 PPS output?
Having designed ruggedized OCXO for harsh rocket environments and tracking floating weather stations before GPS .. actually after only 1st GPS (GOES 1) was launched, it brings back fond memories. The importance of stability depends on outages and how much error you can tolerate during outage or LOS (loss of signal) as well as capture time.
Why is GPS used as a time source?
One increasingly common use is in computer timekeeping, including the NTP protocol. Because GPS is considered a stratum -0 source, a common use for the PPS signal is to connect it to a PC using a low-latency, low- jitter wire connection and allow a program to synchronize to it. This makes the PC a stratum-1 time source.
How is the precision of GPS clock calculated?
• A fully implemented –GPS –XP –NTP clock has a precision of 20 microseconds • NTP enables the GPS time information to be distributed across a local area network (LAN) , thus provide a NIST reference high precision time to every connected computer running NTP. How PPS Works – Garmin Manual