Milestone-Proposal:JJY: Standard Signal Transmitting Station in Japan, 1940
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Docket #:2025-20
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To the proposer’s knowledge, is this achievement subject to litigation? No
Is the achievement you are proposing more than 25 years old? Yes
Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes
Did the achievement provide a meaningful benefit for humanity? Yes
Was it of at least regional importance? Yes
Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes
Has the IEEE Section(s) in which the plaque(s) will be located agreed to arrange the dedication ceremony? Yes
Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes
Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes
Year or range of years in which the achievement occurred:
1940
Title of the proposed milestone:
JJY: Standard Time and Frequency Signal Transmitting Station in Japan, 1940
Plaque citation summarizing the achievement and its significance; if personal name(s) are included, such name(s) must follow the achievement itself in the citation wording: Text absolutely limited by plaque dimensions to 70 words; 60 is preferable for aesthetic reasons.
The Standard Time and Frequency Signal Transmitting Station, constructed by the Electrotechnical Laboratory in Japan in 1940, marked a significant advancement in national standardization. It has transmitted accurate frequency signals since 1940 and time signals since 1948, across Japan, contributing to postwar reconstruction, technological innovation, and societal modernization. Its foundation enabled highly synchronized infrastructure and time-dependent systems essential to modern life in Japan.
200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.
The Standard Time and Frequency Signal Transmitting Station in Japan, constructed in 1940, played a pivotal role in the establishment of a unified national time and frequency standard. Located in Kemigawa (Ibaraki) and operated by the Electrotechnical Laboratory (predecessor of National Institute of Information and Communications Technology), the station began continuous transmission of standard frequency and time (aftere 1948) signals using the call sign JJY. This achievement was based on the precise operation of quartz crystal oscillators and pioneering short-wave radio engineering techniques, which were at the forefront of global standards at the time.
The station enabled the synchronization of clocks across Japan, improving efficiency and accuracy in various sectors, including railways, industry, telecommunications, broadcasting, science, and public life. The availability of reliable time and frequency signals supported technological development during and after World War II and facilitated Japan’s rapid modernization and industrial recovery.
JJY became a cornerstone of Japan’s time dissemination infrastructure, influencing the development of subsequent time and frequency signal services, including the move to long-wave radio transmission from Mount Ohtakadoya and Mount Hagane in later decades. The 1940 milestone represents not only a technical breakthrough in time and frequency standardization but also a profound contribution to societal organization, economic growth, and scientific advancement in Japan.
The enduring impact of the 1940 JJY Station continues to be felt today in systems that rely on precise timing—from Radio-controlled clocks and GNSS synchronization to financial transactions and power grid stability—underscoring its historical and technological significance.
IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.
IEEE Broadcasting Technology Society
IEEE Antennas and Propagation Society
In what IEEE section(s) does it reside?
IEEE Sendai section
IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:
IEEE Organizational Unit(s) paying for milestone plaque(s):
Unit: IEEE Sendai Section
Senior Officer Name: Hiroaki Muraoka
IEEE Organizational Unit(s) arranging the dedication ceremony:
Unit: IEEE Sendai Section
Senior Officer Name: Hiroaki Muraoka
IEEE section(s) monitoring the plaque(s):
IEEE Section: IEEE Sendai Section
IEEE Section Chair name: Hiroaki Muraoka
Milestone proposer(s):
Proposer name: Chiaki Ishikawa
Proposer email: Proposer's email masked to public
Proposer name: Soichi Watanabe
Proposer email: Proposer's email masked to public
Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.
Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):
Mt. Ohtakadoya Standard Time and Frequency Radio Transmission Station, Miyakoji-cho, Tamura-City, Fukushima, 963-4702, Japan
GPS coordinates: 37.3725539,140.8465196,17
Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.
Please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. Mt. Ohtakadoya Standard Time and Frequency Radio Transmission Station, one of the current Standard Time and Frequency Signal Transmitting Stations
Are the original buildings extant?
No. The current Standard Signal Transmitting Stations are located in Fukushima Prefecture (Mt. Ohtakadoya) and Saga Prefecture (Mt. Hagane).
Details of the plaque mounting:
The plaque will be scheduled to be placed in front of the transmission station gate.
How is the site protected/secured, and in what ways is it accessible to the public?
Anyone can view the plaque with permission from the security office.
Who is the present owner of the site(s)?
National Institute of Information and Communications Technology (NICT)
What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include detailed support at the end of this section preceded by "Justification for Inclusion of Name(s)". (see section 6 of Milestone Guidelines)
Historical Significance of JJY
Introduction
The JJY standard time and frequency signal transmitting station, launched in Kemigawa on January 30, 1940 [1-3], was a major milestone in Japan’s advancement in precision time and frequency control. As the second national standard time and frequency radio station in the world (after WWV/USA, 1939) [6], JJY pioneered the dissemination of highly stable time and frequency signals using crystal oscillators and innovative broadcasting methods. It laid the foundation for synchronized communications, scientific measurements, and industrial automation in both pre- and post-war Japan, continuing to influence time and frequency infrastructure today.
Photo 1 Standard Signal Transmitting Station (call sign: JJY) in 1940
[Piction] Official announcement by Japan Gov.: Ministry of Communications Notification No. 1, on January 6, 1940.
Effective January 30, 1940, standard frequency signals will be transmitted using the method described below. January 6, 1940.
Ryutaro Nagai, Minister of Communications.
(1) Location of equipment installation: Kemigawa Town, Chiba Prefecture – Tokyo City Communications Bureau, Kemigawa Station.
(2) Transmitting power: 5 kW.
(3) The transmission signal... [remainder omitted]
Figure 1 Kanpoh on January 6, 1940 [1]
Technological and Scientific Advancements
In response to the growing need for frequency control in the 1920s, Japan’s Ministry of Communications began trials in 1927. These evolved into a national project, culminating in JJY’s launch. The station employed crystal-controlled signals and introduced regular time-interval markers, addressing both frequency calibration and time synchronization.
In the postwar period, JJY advanced to incorporate atomic clocks, aligning with global standards like UT2 and UTC. Japan conducted satellite-based comparisons in the 1970s, confirming JJY's high accuracy down to the nanosecond scale. Transitioning from shortwave (4MHz to 16 MHz) to longwave (40/60 kHz) in the late 1990s enhanced signal stability, coverage, and resilience to atmospheric interference.
Social and Industrial Impact
JJY provided essential calibration services to broadcasters, telecom operators, and scientific institutions. Its signals enabled precise timing in everything from TV subcarriers to electric power grids and transportation systems.
With the spread of radio-controlled clocks in the late 20th century, JJY became a fixture in Japanese daily life. These clocks, widely used in homes, offices, and infrastructure, synchronize automatically, ensuring nationwide punctuality and trust in timekeeping.
International Collaboration and Resilience
JJY contributed to global synchronization by coordinating with services like WWV (USA), and MSF (UK). It played an active role in standardization through CCIR and URSI, aligning Japan with international norms in both frequency and time accuracy [4, 5].
Despite disruptions—wartime suspensions, the Fukushima shutdown in 2011—JJY resumed operations swiftly, demonstrating its critical role and reliability. Its cultural presence remains strong, underpinning systems that shape daily routines and national identity.
Legacy and Ongoing Evolution
Today, JJY operates two longwave transmitters and atomic clock networks via NICT. It supports modern technologies including NTP servers and fiber-based time services, while still serving as a dependable radio fallback. Innovations continue, such as upgrades in control systems and refined atomic transitions [7].
Summary
JJY’s continuous evolution over 85 years exemplifies technological leadership, scientific precision, and societal integration. Its establishment at Kemigawa marks a foundational moment in the global history of standard time and frequency broadcasting, deserving IEEE Milestone recognition.
What obstacles (technical, political, geographic) needed to be overcome?
Obstacles needed to be overcome
A Visionary Endeavor
The 1940 establishment of JJY [1-3], Japan’s first standard time and frequency signal station and only the second in the world (after WWV/USA, 1939) [6], required navigating substantial technical, political, and geographic hurdles—amid a rapidly evolving technological and geopolitical landscape.
Technical Challenges: Frequency Stability and Transmission
Early radio systems suffered from frequency instability, prompting Japan to develop a centralized standard. A quartz-controlled oscillator at Iwatsuki provided the frequency reference, but the need to transmit the signal over 50 km to Kemigawa via telephone lines introduced signal degradation, phase shifts, and electromagnetic interference [3].
To address these issues, Japan upgraded infrastructure: a new facility was established nearby in Makuhari, shielded coaxial cables were installed, and transmitter power was increased from 5 kW to 20 kW. Signal processing systems were also improved, introducing automatic control and time code modulation—major innovations for the era.
Political and Institutional Coordination
Securing political support for such a technically abstract project in pre-war Japan required strategic advocacy. The Diet allocated significant funding—¥140,000 in 1936 and ¥2.8 million in 1940—thanks to the efforts of Ministry of Communications officials.
Multi-agency collaboration was essential: the Tokyo Astronomical Observatory provided accurate time, while the Ministries of Communications and Education managed transmission and regulation. This cooperation enabled precise coordination across all elements of the system.
Geographic and Environmental Considerations
Kemigawa was chosen for its low electromagnetic noise and proximity to Tokyo, but its distance from the Iwatsuki standard source created technical obstacles. Engineers developed specialized grounding, cable routing, and structural reinforcements to address soil conductivity, typhoon risks, and seismic threats.
To overcome atmospheric propagation variability, engineers implemented multi-frequency shortwave broadcasting (initially 4, 7, 9, and 13 MHz) to ensure consistent national coverage—adding complexity to antenna design and signal control.
Wartime Disruptions and Resilience
The onset of the Pacific War halted the expansion of JJY. Resources were diverted, and operations were restricted under military secrecy. Yet, key infrastructure was preserved, and by April 1946—just months after World War II—JJY resumed public broadcasts. This swift recovery underscored the foresight and dedication of its creators.
Lasting Impact
Overcoming these diverse challenges enabled Japan to establish a world-class standard time and frequency system. JJY's reliable broadcasts supported progress in communications, science, industry, and navigation, positioning Japan as an early and lasting contributor to global time and frequency standardization.
What features set this work apart from similar achievements?
Features Set This Work Apart from Similar Achievements
A Globally Distinct Milestone
The JJY station, launched in Kemigawa in 1940 [1-3], was the world’s second standard time and frequency broadcasting station after the U.S. WWV in 1939 [6]. However, it distinguished itself through its early integration of national utility, technical sophistication, and long-term impact across science, industry, and society.
Technological Leadership and Innovation
JJY’s system was notable for linking its transmitting site (Kemigawa) with a frequency reference site (Iwaizumi, later Makuhari) via land cables, achieving frequency stability around 3 × 10⁻⁷—exceptional for its time [5]. Upgrades to crystal oscillators, frequency multipliers, and power output enabled performance on par with international standards despite wartime resource limitations.
Innovative elements included automatic signal generators, manual correction keys, and time-pulse transmission systems. These early features foreshadowed modern digital time signal technologies and positioned JJY as a technical pioneer.
Strategic and International Role
Domestically, JJY was critical to managing Japan’s electromagnetic spectrum—supporting calibration for broadcasters, telecom systems, and radio equipment manufacturers.
Internationally, JJY enabled intercomparison with global stations like WWV (USA) and MSF (UK), contributing to early efforts in time standardization under CCIR. Decades before the atomic era, JJY helped lay the groundwork for global time synchronization and coordinated universal time (UTC).
Transformative Societal Impact
JJY’s influence extended deep into Japanese society:
- Science and Academia: Laboratories, universities, and observatories used JJY for high-precision timing, including eclipse coordination from 1948.
- Transport and Telecom: National railway scheduling and telecom network calibration relied on its consistent timing.
- Consumer Technology: JJY laid the foundation for the widespread adoption of radio-controlled clocks and synchronization devices in homes and industries.
National Integration and Infrastructure-Level Status
JJY was built through cross-agency collaboration involving the Ministry of Communications, the Tokyo Astronomical Observatory, and postwar science bodies. Time correction data was published in the official government gazette, establishing JJY’s legal and civic authority.
This approach marked an early instance of treating timekeeping as essential infrastructure—prefiguring today’s public timing laboratories and GNSS-based synchronization systems.
Endurance and Evolution
Despite interruptions during World War II, JJY resumed operation in April 1946 and expanded services later that year. It adopted multiple frequency bands, improved modulation precision to 0.03 s by 1948, and contributed to international coordination via periodic corrections.
Its evolution into modern longwave transmitters (Ohtakadoya and Hagane) reflects a consistent commitment to reliability and improvement, sustaining Japan’s domestic time synchronization to this day [7].
A Model of National Time Utility
Unlike WWV, which began as a research-oriented facility, JJY was conceived from the outset as a national service—integrating time measurement, regulation, and public dissemination. With legislative funding and infrastructure-level planning, it became the first true national timing utility.
JJY’s model of state-led, socially integrated time broadcasting anticipated the role now played by atomic clocks and satellite timing in modern society.
Summary
JJY stands apart through its early technological innovation, institutional foresight, and societal impact. More than just a follower of WWV in 1939 [6], it was a pioneer in nationalizing and systematizing time as a public utility. Its legacy continues to shape synchronized timekeeping infrastructure in Japan and beyond—making it a fitting candidate for IEEE Milestone recognition.
Why was the achievement successful and impactful?
The Achievement Successful and Impactful
A Pioneering National Initiative
The 1940 launch of the JJY standard time signal station at Kemigawa marked Japan’s entry into global precision timekeeping [1-3]. As the world’s second dedicated standard frequency broadcast facility (after WWV/USA, 1939) [6], JJY played a critical role in addressing the growing need for accurate frequency and time references—laying a foundation for modern communication, broadcasting, navigation, and scientific measurement.
Solving Frequency Instability in Wireless Communications
Before JJY, Japan faced increasing radio interference due to inconsistent transmitter frequencies, a problem exacerbated by the explosive growth of wireless communication. JJY solved this by providing a centralized and reliable reference signal, broadcasting from Kemigawa with a frequency standard maintained initially at Iwatsuki and later relocated to Makuhari for enhanced accuracy and stability.
Technical Success Under Adverse Conditions
Despite wartime resource constraints, JJY achieved a high level of technical performance. Engineers employed precision quartz oscillators and multivibrator-based techniques, reaching early accuracy levels of 3 × 10⁻⁶ and later refining the system to offer precise second-level time signals by 1948. Power output and frequency control improvements helped establish JJY as a national benchmark for timing.
Broad and Lasting Impact
JJY’s success had far-reaching effects:
- Scientific and Industrial Use: It supported time-critical applications in research, astronomy, and defense.
- war Reconstruction: JJY was instrumental in modernizing railways, power grids, and public broadcasting systems.
- Public Accessibility: It introduced standardized time to the general public, enabling widespread clock synchronization and supporting the future development of consumer-grade radio-controlled clocks.
Integration with International Standards
JJY aligned Japan with global timekeeping efforts promoted by the CCIR and the International Telecommunication Union. Through regular comparisons with other national standards, JJY helped Japan build international credibility in precision measurement and contributed to the long-term goal of coordinated universal time (UTC).
Legacy and Continued Importance
The Kemigawa station not only advanced national infrastructure, but also fostered societal trust in timekeeping. Its legacy lives on through longwave transmitters at Mt. Ohtakadoya and Mt. Hagane, still in use for nationwide time synchronization. Millions of radio-controlled devices across Japan owe their precision to the foundation laid by JJY.
Conclusion: A Milestone in Technological and Social Development
JJY’s creation was a decisive response to a major technical challenge of its time and frequency. Its enduring contributions to national infrastructure, international cooperation, and everyday life make it a landmark innovation—worthy of recognition as an IEEE Milestone.
Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.
Reference
[1] The Kanpō (官報): Official announcement by Japan Gov.:
[Translation] Ministry of Communications Notification No. 1, on January 6, 1940. Effective January 30, 1940, standard frequency signals will be transmitted using the method described below. January 6, 1940. Ryutaro Nagai, Minister of Communications. (1) Location of equipment installation: Kemigawa Town, Chiba Prefecture – Tokyo City Communications Bureau, Kemigawa Station. (2) Transmitting power: 5 kW. (3) The transmission signal... [remainder omitted]
[Remarks] "The Kanpō (官報)" is the official government gazette of Japan. It is published by the National Printing Bureau under the Ministry of Finance. The Kanpō serves as a public record for official government information and legal notices.
It includes:
- Laws and ordinances that have been passed by the National Diet and enacted by the government
- Cabinet decisions and official appointments
- Notices from government ministries and agencies
- Corporate legal announcements, such as bankruptcy filings and company registrations
The publication of the Kanpō ensures transparency and legal validity, as many laws and official actions only take effect after they have been published in it.
It is similar to the Federal Register in the United States or the Official Journal of the European Union.
[2] Noriyuki Kurihara: "Longwave Standard Radio Wave: Standard Signal for Radio-Controlled Clocks," IEEJ Journal, pp. 496–499, Vol. 125, No. 8, 2005.
[Translation: Section 3.1, first 10 lines] 3.1 History of Standard Time and Frequency Radio Waves
Standard time and frequency radio waves began operation on January 30, 1940, with the aim of providing standard frequency signals to radio and broadcasting stations. Later, in August 1948, time signal information began to be superimposed onto these standard waves. This time signal has since been widely adopted in Japanese daily life as the reference for time signals on television and radio, as well as for NTT's 117-time service. In this sense, it is no exaggeration to say that standard time and frequency radio waves have supported "time" in postwar Japan for over half a century.
Initially, standard time and frequency radio waves were transmitted using shortwave frequencies. However, because shortwave transmission is highly dependent on ionospheric conditions, several issues began to emerge—such as unstable reception, insufficient frequency accuracy, and signal interference.
[3] Masatoshi Tanaka, Akinori Kikuchi, Shigehisa Honma; “3. Time and Frequency Signal Supply by Shortwave Standard Radio (JJY)”, Quarterly Journal of the Radio Research Laboratories, pp.263–278, Vol. 29 No.149, February 1983
[Translation: Section 2, first 12 lines] 2. The History of the Standard Radio Signal (JJY)
Since its initial transmission, the shortwave standard radio signal (JJY) has been in operation for over 40 years. During this time, the transmission format has undergone numerous changes aimed at improving accuracy. Here, we briefly describe the developments up to the present.
In the early Showa era, as the number of radio communication circuits increased, interference became a significant issue. As a result, it became necessary to transmit standard radio signals to calibrate the frequencies of radio stations. On January 30, 1940 (Showa 15), the Ministry of Communications officially began broadcasting JJY from the Kemigawa transmitting station using a frequency standard device (crystal oscillator) installed at the Iwatsuki receiving station. This marked the formal beginning of JJY transmissions, making it the second such service in the world after the United States (WWV, 1939).
The broadcast frequencies were four shortwave bands: 4, 7, 9, and 13 MHz, and the frequency accuracy was 1 × 10⁻⁸.
[4] National Institute of Information and Communications Technology (NICT); “Time and Frequency Transmission Facilities”, April 2021
[5] National Institute of Information and Communications Technology (NICT); “Japan Standard Time Service Group―Generation, Comparison, and Dissemination of Japan Standard Time and Frequency Standards”, May 2022
[6] Glenn K. Nelson; “A Century of WWV”, Journal of Research of the National Institute of Standards and Technology, Volume 124, Article No. 124025 (2019)
https://doi.org/10.6028/jres.124.025
[7] Michito IMAE, Michiyasu IGARASHI, Chihiro MIKI, Mizuhiko HOSOKA WA,
Yuko HANADO, Kuniyasu IMAMURA, and Atsushi OTSUKA; “5.3 CONSTRUCTION OF NEW LF STANDARD TIME AND FREQUENCY STATIONS”, Quarterly Journal of the Radio Research Laboratories, pp.73-82, Vol.45 Nos.1/2, March/June 1999
[Abstract] Communications Research Laboratory (CRL) is in charge of not only national frequency standards but also the standard frequency and time signal emission in Japan. CRL has started to improve the service of standards time and frequency emission by shifting its main frequency band from the high frequency band (HF) to the low frequency band (LF). The construction of new LF transmission stations is to realize this purpose. These new stations will have more than 10 times of transmission power compared with present experimental transmission station in Ibaraki prefecture. The first new LF station has started transmitting the signal from June 1999, and second one will be completed its construction by 2001. These stations are expected to provide the precise time and frequency signals all over Japan. This paper shows the history of standards frequency and time signal emission in Japan and the concept of CRL’s standard frequency and time signal emission.
Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to ieee-history@ieee.org. Please see the Milestone Program Guidelines for more information. Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to ieee-history@ieee.org with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s). Please recommend reviewers by emailing their names and email addresses to ieee-history@ieee.org. Please include the docket number and brief title of your proposal in the subject line of all emails.
