For many years, India has adhered to Indian Standard Time (IST) as its time reference. Recently, the new Legal Metrology (Indian Standard Time) Rules, 2026 have officially established IST as the mandatory time standard for governmental and commercial activities, mandating synchronization of various systems to time that can be traced back to IST.
Poonam Arora, a Scientist G and Head of the Time & Frequency Metrology Division at CSIR-National Physical Laboratory (NPL), discussed with The Indian Express the significance of “traceable” time, the methods by which organizations will align with IST, and the roles of CSIR-NPL, Regional Reference Standard Laboratories (RRSLs) under the Ministry of Consumer Affairs, and NavIC in the context of India’s timing framework.
The overarching goal is to establish a unified national time reference. Arora stated, “‘One Nation, One Time’ signifies the need for a singular time reference. Currently, various organizations may rely on different time sources, akin to each individual setting their own starting point, which complicates the comparisons of events or measurements.” Below are edited excerpts from her insights:
Arora noted that IST has been the standard for many years and that CSIR-NPL serves as the National Metrology Institute, a designation granted by Parliament to uphold the scientific standards of the nation.
Part of our responsibility includes the maintenance and dissemination of IST. Notably, IST® is a registered trademark of CSIR-NPL. This accomplishment has been a collaborative effort, involving the expertise of NPL scientists and technical staff, guided by successive Directors.
Historically, however, there has been no legal framework to enforce the traceability of time to IST. In contrast, NPL is the body responsible for standards, while enforcement falls under the Department of Legal Metrology, which already oversees measurements like mass and volume. Inspectors can verify the accuracy of measurements at gas stations, but they lacked a similar mechanism for time.
Currently, five Regional Reference Standards Laboratories are responsible for maintaining secondary time scales that are traceable to IST via CSIR-NPL. The Indian Space Research Organisation (ISRO) also ensures that traceability links to IST are in place. This framework allows IST to be disseminated at multiple locations while ensuring alignment with the national reference maintained by CSIR-NPL.
The primary aim is to establish IST as the legal time reference for various commercial applications, including how time is displayed. This initiative is anticipated to enhance cybersecurity, decrease criminal activity, and fortify critical infrastructure.
For instance, the time displayed on personal computers must originate from a reliable source. Users can configure their date and time settings to connect to a Network Time Protocol (NTP) server, which may often be set to an international location, thereby not directly reflecting IST.
Individuals currently derive time from numerous sources, frequently through GPS. A telecom provider might offer a time signal based on its centralized data, but discrepancies of seconds or even minutes can arise.
During travel, for example, different FM stations may report conflicting times, leading to confusion. The implementation of IST would establish a consistent national time reference.
Establishing traceability can be achieved through various technologies. NPL provides an NTP service via a designated domain name, enabling users to synchronize their systems with IST.
NTP is widely regarded as the most accessible method, operating over the internet. Alternatives include Precision Time Protocol (PTP), satellite connections, and optical links, with the choice depending on the required accuracy.
The level of accuracy required is contingent upon the application. For instance, ISRO needs to maintain traceability to IST within nanoseconds, while NPL keeps national time aligned within a few nanoseconds of the international reference, UTC.
For many everyday applications, NTP can achieve millisecond accuracy, whereas PTP is capable of providing microsecond accuracy, particularly effective within local networks.
Once synchronized, any clock or oscillator will begin to drift over time. Therefore, NTP continuously verifies the reference at set intervals, which can be adjusted based on how closely a system needs to align with IST.
For applications requiring extreme precision, satellite links are utilized for exact time transfer. NPL supplies time to ISRO through satellite connections, employing methods such as Common-View GNSS and two-way satellite time and frequency transfer. Optical links utilizing dedicated dark fiber can achieve picosecond accuracy, although their availability is limited.
Most users do not need the sophisticated systems utilized by ISRO. However, sectors like defense and other critical operations may demand such high precision, while banking and finance might only require millisecond-level NTP services.
Organizations will need to demonstrate compliance by ensuring their systems are synchronized with IST. This can be verified through a computer’s settings, which indicate the selected time server or domain. NPL, NIC, and the RRSLs provide their own services, and a direct PTP or satellite connection could also confirm that the organization is obtaining time from an authorized source.
Currently, there are no exemptions from this requirement. However, establishments such as hotels or ISRO launch centers may need to display other time zones, which can be accommodated as long as IST is also prominently displayed and used as the reference.
This requirement extends beyond mere display; it necessitates synchronization so that “the seconds commence simultaneously across various applications and sectors.”
The enforcement of these regulations will fall under the purview of the Legal Metrology Department, with NPL providing advisory support, having played a role in establishing regional time scales and dissemination techniques. A compliance verification mechanism will be developed over time to ensure adherence to these new regulations.
