Phase Noise Impact on the Short-Term Frequency Stability of a Frequency Source

Abstract

The impact of phase noise on the short-term frequency stability (i.e. the Allan deviation with smaller averaging time) of a frequency source has been discussed in detail in the paper. The paper also describes a technique to estimate the Allan deviation values of a frequency source from its measured phase noise plot. Using the technique described here, the Allan deviations of a 10 MHz Rubidium Atomic Frequency Source (RAFS) of an IRNSS (Indian Regional Navigation Satellite System) satellite have been estimated. The estimated Allan deviation values thus obtained from the measured phase noise plot of the RAFS are then compared with the measured Allan deviation values obtained by standard methods (such as the Standard Reference Source method and the 3-Corner Hat method) during Integrated Spacecraft Testing of the IRNSS satellites.

KEYWORDS:

• Allan deviation
• Allan variance
• FM (frequency modulation) noise
• PM (phase modulation) noise
• Rubidium atomic frequency source (RAFS)
• Single sideband (SSB) phase noise density

ACKNOWLEDGEMENTS

The authors are thankful to the Deputy Director, ICA, Shri V K Hariharan for his constant encouragements and motivations for writing this paper. The authors also extend their sincere gratitude to the IRNSS Project Director (Space segment), Shri V Ramanathan for giving the opportunity to carry out this work. Finally, the authors are very much thankful to Mr. Kamalakar (ex Director, Laboratory for Electro-optical Sensor/ISRO, Bangalore) for giving the precious time and effort during verifying the paper meticulously.

Additional information

Notes on contributors

Md. Tosicul Wara

Md Tosicul Wara is a scientist at UR Rao Satellite Centre. He joined ISRO in 1993 after completing ME in electronics & communication. His field of interest includes satellite communication, global navigational satellite system (GNSS) and microwave measurement & instrumentations. He is a Fellow of the Institution of Electronics & Telecommunication Engineers (IETE) and the Life Member of Astronautical Society of India (ASI).

M. S. Bhuvaneshwari

M S Bhuvaneshwari is a scientist in UR Rao Satellite Centre. She joined ISRO in 1987 after graduating in electronics & communication. Currently, she is heading GEOSAT RF & Payload Checkout Division-2 (GRCD-2) of Spacecraft Checkout Group at UR Rao Satellite Centre. Measurement & process automation, innovative software & measurement development, visualization & data mining are her areas of interest. Email: [email protected]

M. R. Raghavendra

M R Raghavendra is a scientist at UR Rao Satellite Centre. He joined ISRO in the year 1992. His research interest includes RF communication systems, digital signal processing, design & development of analog & digital demodulators. Presently, he is the head of GEOSAT RF & Payload Checkout Division-1 (GRCD-1) of Spacecraft Checkout Group at UR Rao Satellite Centre. Email: [email protected]

Usha Bhandiwad

Usha Bhandiwad is a scientist at UR Rao Satellite Centre (URSC) and presently she is the group director of Spacecraft Checkout Group (SCG) of URSC. She received BE degree in electronics and communication engineering from Karnataka University, Dharwad. Presently, her work areas include design, development and realization of simulators and providing automation for spacecraft testing. Email: [email protected]