Standardisation and Calibration of Various Equipment by the Use of Standard Frequency Transmissions

Abstract

The standard frequency transmissions are now-a-days widely employed for calibration and standardisation of various equipment. The precision of measurement based on such transmissions is often limited by the stability of the ionospheric propagation characteristics involved. In India, we are now having standard time and frequency broadcast from the National Physical Laboratory, New Delhi at 10 MHz and 15 MHz. By employing both the transmissions, it may be possible to reduce the error due to ionospheric changes and to obtain standards of frequency at 2.5 MHz and 12.5 MHz without involving a precision local oscillator in the receiving system. The system is also capable of measuring the precision of an oscillator at 12.5 MHz in case where the ionospheric error may be neglected. A set up for studying the differential ionospheric shift between 10 MHz and 15 MHz without involving a precision local oscillator has been suggested and a theoretical estimate of the differential shift is also made. Improvement of precision obtainable with diversity receiving system is also critically examined.

Indexing Terms:

• Standard Frequency Transmissions
• Equipment Calibration
• Diversity
• Receiving System

Additional information

Notes on contributors

S. K. Saha

SAHA, S K: Born on 10th May, 1950 in Comilla (Bangladesh). Obtained BSc degree from Chittagong University in 1969 and MSc degree in Applied Physics from the University of Rajshahi in 1971. Specialized in Solid-State Physics. Joined as a CAS Junior Research Fellow on 2nd August, 1976. Since then, has been working at the Centre of Advanced Study in Radio Physics and Electronics, University of Calcutta for PhD degree on the ‘Studies on the ionospheric propagation characteristics of standard frequency signals in the HF band at Calcutta. He has developed X-tal controlled solid-state receiver for recording ATA signals. He has a few research papers to his credit.

R. N. Ghosh

GHOSH, R N: Born in 1950, graduated with Physics Hons, from Calcutta University and obtained his BTech degee in Radio Physics & Electronics in 1973. Completed his M. Tech degree in the same subject in 1975 from Calcutta University with specialization in Advanced Radio Engineering & Microwave Electronics. Joined Telerad (P) Ltd. and worked with Television for sometime. At present, working in the National Test House, Calcutta. Shri Ghosh has published a number of papers. His fields of interest are measurements and Standardisation, HF & VHF Communication and Digital Electronics.