What is the National Atomic Clock and why is it constantly listening to navigation satellites?

On the occasion of the day of the reversal of winter starting today, explains Dr. Nadia Goldowski – in charge of time and frequency measurements In the National Physics Laboratory at the Ministry of Economy and Industry in an interview with the Scientist website on how to determine the time in her laboratory using atomic clocks

The time of the State of Israel is determined in the National Physics Laboratory of the Ministry of Economy with the help of a special system that compares the time measurement results in Israel 86600 times a day with the time measurement results of other national laboratories in the world. Explains Dr. Nadia Goldowski – in charge of time and frequency measurements in the National Physics Laboratory at the Ministry of Economy and Industry in an interview with the Scientist website

The National Laboratory of Physics is in fact the state clock and the national standard for time. Israel time is determined by the Time Law of 1992. The laboratory determines and measures the time and frequency used for security and civilian purposes such as: television broadcasts, telephone calls, computers, navigation devices and military systems such as: “Iron Dome”, “Arrow” system and “Magic Wand” “.

In the National Laboratory there are four atomic clocks of the cesium type, equipment For international comparisons, equipment for performing measurements and calibrations for industrial and military customers such as: Rafael, Elbit, IAI, Air Force, Electric Company.

in 2019 in accordance with the national standard for time And frequency, a new generation of atomic clocks was introduced as well as an innovative system for international comparisons. As a result of the renewal of the equipment, the national standard accuracy has risen to a level of 1X10 ^{– 14} .

In an interview with the scientist’s website, Dr. Golodovsky explained that according to the 1992 Time Law, Israeli national time must be determined by precise atomic clocks based on cesium and they must be synchronized. To the global time based on clock measurements in similar laboratories around the world. “We keep track of the exact time and make comparison measurements with the clocks around the world and also on satellites in all these measurements.”

How do atomic clocks work?

“The accuracy of our ten clocks is powerful Minus 14. There are also precision clockwork of exactly ten to the power of 16 built inside a cooling chamber to a temperature of almost absolute zero. We are aware that because of the lower level of accuracy we have a deviation from the world clock. However, because we measure the frequency in all atomic clocks in front of the world clock, the accuracy increases to ten to the power of minus 15.

We actually measure the times reported to us by all the navigation satellites that are In space, whether it’s GPS, European Galileo satellites or Russian Galonas. Every navigation satellite has an atomic clock and sometimes even two or three. However and they are less accurate than the watches found in 85 labs like ours around the world. We check the watches that are on the satellite, make comparisons between them and our watches and send the data to an international center located in Paris. We test our accuracy on satellite systems and they get the fixes to keep track of the global time we all see on phones and computers. That you get both on the phone and on computers and everywhere.

Measuring time is important for navigation, satellites, airplanes, military uses, geodesy, geology, communications and more. Therefore, the same laboratories located in developed countries, including Israel, calibrate the satellites and transmit the data through the center in Paris to the satellite operators. This created a huge global network for determining time.

Our system analyzes data from up to eight satellites simultaneously, with each satellite observed by us for about 13 minutes.

What are the plans next?

Technology The methods and equipment are advanced and there are already watches in the world Exactly ten to the power of minus 18.

We have four watches in the lab with an accuracy of ten to the power of minus 14. I hope they will also buy atomic clocks based on accurate hydrogen lasers. 10 times the cesium clocks, ie an accuracy of ten to the power of minus 15.

More on the subject on the scientist’s website: