S.V. Ermak1, V.V. Semenov2, O.V. Ermak3

1,2 Higher school of applied physics and space technologies, Institute of Electronics and Telecommunications, Peter The Great St. Petersburg Polytechnic University (Saint-Petersburg, Russia)

3 Higher School of Hydraulic and Power Engineering, Institute of Civil Engineering, Peter The Great St. Petersburg Polytechnic University (Saint-Petersburg, Russia)

Formulation of the problem. Rubidium atomic clocks are widely used in the onboard equipment of mobile systems (for example, navigation satellites), but their accuracy is influenced by such external factors as variations of the geomagnetic field in magnitude and direction.

Target. Carrying out studies of the influence of the frequency orientation dependence of an onboard rubidium atomic clock located in a geomagnetic field varying in direction and magnitude, as well as to demonstrate the possibility of suppressing the orientation error of an atomic clock due to the difference in the longitudinal and transverse shielding coefficients of the magnetic screen of an atomic clock by using a system of two rubidium atomic clocks with different mutual orientations of optical axes.

Results. The influence of the frequency orientation dependence of the onboard rubidium atomic clock caused by the difference in the longitudinal and transverse shielding coefficients of the magnetic screen is experimentally investigated. The created experimental setup ensured the measurement of fluctuations in the frequency of one atomic clock relative to the frequency of other atomic clocks of the same type, or laboratory atomic clocks not subject to the influence of an alternating external magnetic field. The comparison of the frequencies of the onboard rubidium atomic clock was carried out using a frequency comparator with the construction of time dependences of the relative frequency fluctuations and the corresponding Allan deviations. The possibility of compensating by more than 4 times the relative fluctuations of the frequency of two similar small-sized commercial rubidium atomic clocks (co-directional orientation of the optical axes of the clock), operating in a directionally changing external magnetic field with an amplitude of 0.45 Oe, was experimentally demonstrated. corrections to the frequency of the atomic clock in comparison with the light shift by varying the orientation of the external magnetic field.

Practical significance. The presented research results demonstrated the possibility of suppressing the orientation dependence of the average frequency of the onboard synchronization system, which consists of two small rubidium atomic clocks of the same type, the optical axes of which are oppositely directed.

Ermak S.V., Semenov V.V., Ermak O.V. Study of the possibility of suppressing the influence of changes in an external magnetic field direction on the relative frequency fluctuations of two rubidium atomic clocks. Radiotekhnika. 2021. V. 85. № 12. P. 129−138.  DOI: https://doi.org/10.18127/j00338486-202112-11 (In Russian)

1. Kurshin A.V. Povyshenie tochnosti opredelenija mestopolozhenija potrebitelej GLONASS putem uvelichenija chastoty zakladok vremennoj informacii na sputniki. Trudy MAI (jelektronnyj zhurnal). 2012. № 57. C. 1−7 (In Russian).
2. Svehla D. Geometrical Theory of Satellite Orbits and Gravity Field. Springer. 2018. 537 р.   
3. Bandura A.S. Evaluation of the accuracy of the data of navigation messages of spacecraft of satellite radio navigation systems. Scientific and Technical Journal of Information Technologies, Mechanics and Optics. 2006. № 6. Р. 215−221. 
4. Grigor'janc V.V., Zhabotinskij M.E., Zolin V.F. Kvantovye standarty chastoty. Nauka. 1968. 288 s. (In Russian).
5. Mathur B.S., H. Tang and W. Happer. Light shifts in alkali atoms. Physical Review. 1968. V. 171. P. 11−19.
6. Semenov V.V. O vklade tenzornoj komponenty v svetovoj sdvig chastoty radioopticheskogo SVCh-rezonansa v parah rubidija. Izvestija vuzov. Ser. Fizika. 1999. № 2. S. 86−90 (In Russian).
7. Baranov A.A., Ermak S.V., Semenov V.V. Orientacionnye sdvigi chastoty SVCh-rezonansa na sverhtonkom 0−0-perehode v parah rubidija-87 s selektivnoj opticheskoj nakachkoj. Optika i spektroskopija. 2013. № 114. S. 18−21 (In Russian).
8. Baranov A., Ermak S. and Semenov V. The orientation dependence of the SHF radio-optical resonance frequency light shift in rubidium vapors. Proceedings of the IEEE International Frequency Control Symposium and Exposition. May 2011. № 5977289. P. 580−581.
9. Baranov A.A., Ermak S.V., Lozov R.K., Semenov V.V., Ermak O.V. Vlijanie orientacionnogo sdviga chastoty kvantovogo datchika s opticheskoj nakachkoj na izmerenija parametrov orbity sputnikov navigacionnyh sistem. Radiotehnika. 2018. № 12. S. 5−12 (In Russian).
10. Lozov R.K., Ermak S.V., Semenov V.V., Ermak O.V. Modelirovanie vlijanija geomagnitnogo polja na tochnost' atomnyh chasov bortovoj apparatury sistem sputnikovoj navigacii. Radiotehnika. 2019. T. 83. № 12(20). S. 32−37 (In Russian).
11. Rile F. Standarty chastoty: Principy i prilozhenija: Per. N.N. Kolachevskogo. M.: FIZMATLIT. 2009. 512 s. (In Russian).