Broadcasting and Standard Time and Frequency Dissemination

Abstract

All India Radio has been rendering time dissemination service right from its inception and presently it broadcasts time signal pips almost on an hourly basis from 0600 to 2300 hours I.S.T. on medium and shortwave frequencies. In order to improve the accuracy of these time signal pips, Research Department of All India Radio in collaboration with National Physical Laboratory, New Delhi developed a solid state, interface logic unit for use with Caesium Atomic Clock for synchronization of AIR time signal pips.

In India, NPL, New Delhi disseminates standard time and frequency information under the call sign ‘ATA’ on 5,10 and 15 MHz frequencies. In order to assess the reception of ATA/NPL transmissions in India, AIR had conducted monitorings of these broadcasts and results were reported. The predicted field strength values have been found to agree fairly well with the observations. However, these investigations were based on very limited monitorings made at a few locations in India. Recently, AIR again conducted similar monitorings at many receiving centres of AIR situated in different parts of the country. These monitorings have confirmed that ATA/NPL transmissions are capable of satisfactory reception of standard time and frequency signals in most parts of the country on at least one of the three standard frequencies. A need to improve the reception of these signals in certain parts of India has also been felt.