Milestone-Proposal:JJY: Standard Signal Transmitting Station in Japan, 1940
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Docket #:2025-20
This proposal has been submitted for review.
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 JJY Standard Time and Frequency Signal Transmitting Station, established in 1940 in Kemigawa, Chiba, was Japan’s first facility for disseminating national time and frequency standards. Operated by the Electrotechnical Laboratory (predecessor of NICT), JJY began transmitting accurate frequency signals in 1940 and added standard time signals in 1948. Its operation relied on quartz crystal oscillators and advanced shortwave radio engineering, representing a pioneering achievement in global timekeeping technology.
JJY enabled synchronization of clocks and systems across Japan, enhancing efficiency in railways, telecommunications, broadcasting, scientific research, and public services. During and after World War II, JJY played a vital role in Japan’s technological development and industrial recovery, supporting the modernization of infrastructure and society.
As one of the earliest national time signal stations globally—following the U.S. WWV—JJY contributed to international time coordination and inspired subsequent developments in longwave transmission from Mount Ohtakadoya and Mount Hagane. Its signals became the foundation for Japan’s widespread adoption of radio-controlled clocks, which automatically synchronize with JJY broadcasts. These clocks are now ubiquitous in homes, offices, and public infrastructure, ensuring nationwide punctuality and trust in timekeeping.
JJY’s legacy continues today in systems that rely on precise timing, including GNSS synchronization, financial networks, and power grid stability. The 1940 JJY station represents a landmark in both technological innovation and societal advancement, demonstrating how precision timekeeping can underpin national progress and global integration.
IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.
IEEE Broadcasting Technology Society
IEEE Antennas and Propagation Society
IEEE Ultrasonics, Ferroelectrics, and Frequency Control 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. Although the original JJY station was established in Kemigawa, Chiba, the Mt. Ohtakadoya site represents the direct operational successor of JJY’s legacy. It continues the uninterrupted transmission of Japan’s national standard time and frequency signals, preserving the historical function and significance of the original achievement.
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 mounted on a dedicated pedestal in front of the main gate of the Mt. Ohtakadoya transmission station. It will be clearly visible to visitors and protected by site security.
How is the site protected/secured, and in what ways is it accessible to the public?
The site is owned and operated by the National Institute of Information and Communications Technology (NICT), which has agreed to host the IEEE Milestone plaque. Visitors may view the plaque. The site is secured and maintained by NICT, ensuring long-term preservation and public accessibility.
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, inaugurated in Kemigawa on January 30, 1940 [1–3], marked a pivotal moment in Japan’s advancement in precision timekeeping. As the world’s second national standard time and frequency radio station—following WWV in the United States (1939) [6]—JJY pioneered the continuous dissemination of highly stable signals using quartz crystal oscillators and innovative shortwave broadcasting techniques. This achievement laid the foundation for synchronized communications, scientific measurement, and industrial automation in both prewar and postwar Japan, and continues to influence national infrastructure today.
Photo 1 Overall View of Kemigawa Standard Signal Transmitting Station (call sign: JJY) in 1940
Photo 2 Main Entrance and Antenna of Kemigawa Standard Signal Transmitting Station
[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
Responding to increasing demands for frequency control in the 1920s, Japan’s Ministry of Communications initiated experimental broadcasts in 1927. These efforts culminated in the launch of JJY, which introduced crystal-controlled signals and regular time-interval markers—addressing both frequency calibration and time synchronization needs.
Postwar, JJY evolved to incorporate atomic clocks and align with international standards such as UT2 and UTC. In the 1970s, Japan conducted satellite-based time comparisons, achieving nanosecond-level accuracy. The transition from shortwave (4–16 MHz) to longwave (40/60 kHz) in the late 1990s further enhanced signal stability, coverage, and resistance to atmospheric interference.
Social and Industrial Impact
JJY provided essential calibration services to broadcasters, telecommunications providers, scientific institutions, and public utilities. Its signals enabled precise timing for television subcarriers, electric power grids, railway systems, and more. By the late 20th century, JJY-supported radio-controlled clocks became ubiquitous in homes, offices, and infrastructure—ensuring nationwide punctuality and public trust in timekeeping.
International Collaboration and Resilience
JJY contributed to global time synchronization by coordinating with services such as WWV (USA) and MSF (UK), and actively participated in international standardization through CCIR and URSI [4, 5]. Despite wartime suspensions and the 2011 Fukushima shutdown, JJY resumed operations swiftly, underscoring its resilience and national importance. Its cultural and technological presence remains deeply embedded in Japan’s identity.
Legacy and Ongoing Evolution
Today, JJY operates two longwave transmitters and a network of atomic clocks under NICT. It supports modern technologies including NTP servers, GNSS synchronization, and fiber-based time services, while continuing to serve as a reliable radio-based fallback. Ongoing innovations include refined atomic transitions and upgraded control systems [7].
Summary
JJY’s 85-year evolution exemplifies Japan’s leadership in time and frequency technology. Its establishment in 1940 represents a foundational achievement in global time dissemination, with enduring contributions to science, industry, and society. This legacy merits recognition as an IEEE Milestone.
What obstacles (technical, political, geographic) needed to be overcome?
Obstacles needed to be overcome
A Visionary Endeavor
The establishment of JJY in 1940 [1–3]—Japan’s first standard time and frequency signal station and the world’s second after WWV (USA, 1939) [6]—required overcoming significant technical, political, and geographic challenges. This achievement emerged during a period of rapid technological change and geopolitical uncertainty, demanding visionary planning and cross-sector collaboration.
Technical Challenges: Frequency Stability and Transmission
Early radio systems in Japan suffered from frequency drift and instability, prompting the need for a centralized national standard. A quartz-controlled oscillator at Iwatsuki provided the reference signal, but transmitting it over 50 km to Kemigawa via telephone lines introduced phase shifts, attenuation, and electromagnetic interference [3].
To mitigate these issues, engineers implemented several innovations:
- A new relay facility was constructed in nearby Makuhari.
- Shielded coaxial cables replaced standard lines.
- Transmitter power was increased from 5 kW to 20 kW.
- Automatic control systems and time code modulation were introduced—pioneering technologies for the era.
These advancements ensured signal integrity and laid the groundwork for future time dissemination systems.
Political and Institutional Coordination
Securing political support for a technically abstract and non-commercial project in prewar Japan was a major hurdle. Through strategic advocacy, the Ministry of Communications obtained substantial funding—¥140,000 in 1936 and ¥2.8 million in 1940.
The project required coordination across multiple institutions:
- The Tokyo Astronomical Observatory provided precise time data.
- The Ministries of Communications and Education oversaw transmission and regulatory frameworks.
This inter-agency collaboration was essential to the system’s success and sustainability.
Geographic and Environmental Considerations
Kemigawa was selected for its low electromagnetic noise and proximity to Tokyo. However, its distance from the Iwatsuki oscillator introduced technical challenges. Engineers addressed these through:
- Specialized grounding systems to manage soil conductivity.
- Structural reinforcements to withstand typhoons and earthquakes.
- Careful cable routing to minimize signal degradation.
To ensure nationwide coverage despite atmospheric variability, JJY adopted multi-frequency shortwave broadcasting (initially 4, 7, 9, and 13 MHz), which required complex antenna design and signal control systems.
Wartime Disruptions and Resilience
The outbreak of the Pacific War halted JJY’s planned expansion. Resources were diverted, and operations were restricted under military secrecy. Nevertheless, core infrastructure was preserved. Remarkably, JJY resumed public broadcasts by April 1946—just months after the war’s end—demonstrating the foresight and diligence of its creators.
Lasting Impact
By overcoming these diverse challenges, Japan succeeded in establishing a world-class standard time and frequency system. JJY’s reliable broadcasts supported advancements in communications, science, industry, and navigation, positioning Japan as a global contributor to 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
JJY, launched in Kemigawa in 1940 [1–3], was the world’s second standard time and frequency broadcasting station, following WWV in the United States (1939) [6]. Unlike WWV, which originated as a research facility, JJY was conceived from the outset as a national infrastructure project—integrating precision timekeeping with public service, regulation, and industrial utility. This strategic orientation set JJY apart as a pioneering model of national time dissemination.
Technological Leadership and Innovation
JJY achieved exceptional frequency stability (approx. 3 × 10⁻⁷) [5] by linking its transmission site in Kemigawa with a reference oscillator in Iwatsuki (later Makuhari) via land cables. Despite wartime resource constraints, Japan implemented advanced technologies including:
- Crystal oscillators and frequency multipliers
- Automatic signal generators and manual correction systems
- Time-pulse transmission and early modulation techniques
These innovations anticipated modern digital time signal systems and demonstrated Japan’s technical leadership in radio engineering.
Strategic and International Role
Domestically, JJY played a central role in managing Japan’s electromagnetic spectrum, providing calibration services for broadcasters, telecom networks, and equipment manufacturers.
Internationally, JJY contributed to early global time synchronization efforts by coordinating with WWV (USA), MSF (UK), and participating in CCIR and URSI standardization activities [4, 5]. JJY’s operations laid the groundwork for Japan’s integration into the global UTC framework, decades before atomic timekeeping became widespread.
Transformative Societal Impact
JJY’s influence extended across multiple sectors:
- Science and Academia: Laboratories and observatories used JJY for high-precision timing, including eclipse coordination from 1948.
- Transportation and Telecommunications: National railway schedules and telecom networks relied on JJY’s consistent timing.
- Consumer Technology: JJY enabled the widespread adoption of radio-controlled clocks, enhancing punctuality and trust in timekeeping across society.
National Integration and Infrastructure-Level Status
JJY was developed through coordinated efforts among the Ministry of Communications, Tokyo Astronomical Observatory, and postwar scientific institutions. Time correction data was published in the official government gazette, establishing JJY’s legal authority and civic role.
This institutional framework marked one of the earliest examples of treating timekeeping as essential national infrastructure—prefiguring today’s atomic clock laboratories and GNSS-based synchronization systems.
Endurance and Evolution
Despite wartime interruptions, JJY resumed operations 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 through periodic corrections.
JJY’s evolution into longwave transmitters at Mt. Ohtakadoya and Mt. Hagane reflects a sustained commitment to reliability and innovation. Today, JJY continues to support Japan’s time synchronization needs through atomic clocks, NTP servers, and fiber-based time services [7].
A Model of National Time Utility
JJY was not merely a technical achievement—it was a strategic initiative to nationalize timekeeping. With legislative funding, cross-agency planning, and public dissemination, JJY became the world’s first fully integrated national time utility.
Its model anticipated the role of atomic clocks and satellite-based timing in modern infrastructure, making JJY a foundational example of time as a public good.
Summary
JJY stands apart through its early technological innovation, institutional foresight, and transformative societal impact. More than a follower of WWV, JJY pioneered the nationalization and systematization of time dissemination. Its legacy continues to shape synchronized timekeeping infrastructure in Japan and globally—making it a compelling candidate for IEEE Milestone recognition.
Why was the achievement successful and impactful?
The Achievement Successful and Impactful
A Pioneering National Initiative
The launch of JJY in 1940 at Kemigawa marked Japan’s formal entry into global precision timekeeping [1–3]. As the world’s second dedicated standard frequency broadcast station—following WWV in the United States (1939) [6]—JJY addressed the growing national need for accurate time and frequency references. It laid the foundation for modern communication, broadcasting, navigation, and scientific measurement in Japan.
Solving Frequency Instability in Wireless Communications
Prior to JJY, Japan faced increasing radio interference due to inconsistent transmitter frequencies, exacerbated by the rapid expansion of wireless communication. JJY resolved this by providing a centralized, stable reference signal. Initially maintained at Iwatsuki and later relocated to Makuhari for enhanced accuracy and stability, the frequency standard was transmitted to Kemigawa, enabling nationwide calibration and synchronization.
Technical Success Under Adverse Conditions
Despite wartime resource constraints, JJY achieved remarkable technical performance:
- Precision quartz oscillators and multivibrator-based systems delivered early accuracy of 3 × 10⁻⁶.
- By 1948, JJY provided second-level time signals with modulation precision of 0.03 s.
- Transmitter power and frequency control were continuously improved, establishing JJY as Japan’s national benchmark for time and frequency dissemination.
These achievements demonstrated Japan’s engineering resilience and innovation under challenging conditions.
Broad and Lasting Impact
JJY’s influence extended across multiple domains:
- Scientific and Industrial Use: Supported time-critical applications in astronomy, geophysics, and defense.
- Postwar Reconstruction: Enabled modernization of railways, power grids, and broadcasting systems.
- Public Accessibility: Introduced standardized time to the general public, facilitating widespread clock synchronization and paving the way for consumer-grade radio-controlled clocks.
JJY became a trusted source of time for both institutional and everyday use.
Integration with International Standards
JJY aligned Japan with global timekeeping efforts led by the CCIR and the International Telecommunication Union. Through regular intercomparisons with WWV (USA), MSF (UK), and other national stations, JJY contributed to the development of Coordinated Universal Time (UTC) and enhanced Japan’s credibility in precision measurement.
Legacy and Continued Importance
The Kemigawa station not only advanced national infrastructure but also fostered public trust in timekeeping. JJY’s legacy continues through longwave transmitters at Mt. Ohtakadoya and Mt. Hagane, which remain operational for nationwide time synchronization.
Today, millions of radio-controlled devices across Japan rely on JJY’s signals, and its infrastructure supports modern technologies.
Conclusion: A Milestone in Technological and Social Development
JJY was a decisive response to the technical challenges of its time. Its enduring contributions to national infrastructure, international cooperation, and daily life exemplify the transformative power of precision timekeeping. JJY stands as a landmark innovation—fully deserving 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.
