![ishara signal timing solutions ishara signal timing solutions](https://ops.fhwa.dot.gov/publications/fhwahop08024/images/6_26.png)
In any event, GNSS clock synchronization eliminates the need for manual clock setting (an error-prone process) to establish traceability to national and international standards. Still, local atomic clocks are sometimes desired as a long-term back-up solution in the event of a GNSS signal loss such as a weather-related outage, signal interference or other scenarios such jamming or spoofing.
![ishara signal timing solutions ishara signal timing solutions](https://pubs.acs.org/na101/home/literatum/publisher/achs/journals/content/aamick/2017/aamick.2017.9.issue-19/acsami.7b03017/20170511/images/large/am-2017-03017t_0002.jpeg)
It is the process of synchronization to GNSS that can provide atomic clock accuracy without the need for a local atomic clock. Typical accuracies range from better than 1 microsecond to a few milliseconds depending on the synchronization protocol. GPS/GNSS satellites include three or four atomic clocks that are monitored and controlled so that they are highly synchronized and traceable to national and international standards (known as Coordinated Universal Time, or UTC).įor time synchronization, the GNSS signal is received, processed by a local master clock, time server or primary reference, and passed on to downstream devices, systems or networks so that their local clocks are also synchronized to UTC. However, atomic clocks themselves do not guarantee traceability and synchronization with other clocks. Of the three, Rubidium clocks often provide the best combination of cost, size and overall performance, and are often a requirement for highly reliable master clock systems. Rubidium, Cesium and Hydrogen Maser clocks are very accurate. What is more, server clocks often drift by 200 ppm-about 50 times worse, and unacceptable to most network architects.Ĭlocks locked to atomic standards are much more stable timekeepers.
![ishara signal timing solutions ishara signal timing solutions](https://www.omicron-lab.com/fileadmin/assets/RFGeek_Jokes/Speed_of_Light_Large.jpg)
If a fairly decent clock is off by just 10 parts per million (ppm), it will gain or lose almost a second a day. Over time, one consistently requires an extra 0.04 milliseconds to increment itself by a second.īy the end of a year, the two clocks will differ by more than 20 minutes. However, clocks are often designed for low cost rather than keeping accurate time.Įven fairly accurate computer clocks are likely to vary due to manufacturing issues, changes in temperature, electric and magnetic interference, the age of the quartz crystal, or even system load.Īdditionally, even the smallest errors in keeping time can add up significantly over a long period.Ĭonsider two clocks that are synchronized at the beginning of the year. Electronic clocks control critical functions in many applications.