Milestone-Proposal:Emergency Warning Code Signal Broadcasting System

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Docket #:2014-13

This Proposal has been approved, and is now a Milestone

To the proposer’s knowledge, is this achievement subject to litigation?

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:


Title of the proposed milestone:

Emergency Warning Code Signal Broadcasting System, 1985

Plaque citation summarizing the achievement and its significance:

NHK (Japan Broadcasting Corporation) began broadcasting emergency warning code signals in 1985. The system embedded signals within AM and FM radio broadcasts that provided reliable and prompt transmission of emergency warning information to the public. During the course of digital TV standardization, the warning codes were integrated into technical standards of international satellite and terrestrial broadcasting.

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.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

In what IEEE section(s) does it reside?

IEEE Tokyo Section

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: IEEE Tokyo Section Treasurer
Senior Officer Name: Seishi Takamura

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: IEEE Tokyo Section Secretary
Senior Officer Name: Isamu Chiba

IEEE section(s) monitoring the plaque(s):

IEEE Section: IEEE Tokyo Section Chair
IEEE Section Chair name: Toshitaka Tsuda

Milestone proposer(s):

Proposer name: Dr. Toru Kuroda, Director of NHK (Japan Broadcasting Corporation) Science & Technology Research Laboratories.
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):

1-10-11 Kinuta,Setagaya, Tokyo 157-8510 Japan

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 address(es) of the plaque site(s) (GPS coordinates if you have them). Also 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. The intended site of the milestone plaque is NHK Science and Technology Research Laboratories (STRL). 1-10-11 Kinuta, Setagaya, Tokyo, 157-8510, Japan

Are the original buildings extant?

No, the present building was built on the same location as the old labs.

Details of the plaque mounting:

The new milestone plaque will be installed next to the “First Direct Broadcast Satellite Service” plaque awarded in 2011, which is located outside the building of NHK Science and Technology Research Laboratories, but within the laboratories lot at the entrance space. Every visitor to the laboratories will be able to see the milestones plaques.

How is the site protected/secured, and in what ways is it accessible to the public?

The plaque will be permanently embedded in a block of marble placed near the entrance of the building of the laboratories. The NHK STRL is guarded by security personnel at the gate of the laboratories’ property and at the entrance of the building. A security camera monitors the plaque and the entrance at all times and the gate is securely locked during the evening. The lobby is open to the public and visitors will be able to walk by the plaque which will be on open display.

Who is the present owner of the site(s)?

NHK (Japan Broadcasting Corporation)

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

The “Basic Plan of Protection against Disasters in a Tokai Earthquake”, based on “the Act on Special Measures against Large-scale Earthquakes” that was enacted in 1978 by the Japanese Government was proclaimed in anticipation that a large-scale earthquake would occur in the Tokai area. Part of this plan was to warn the public of earthquakes and tsunamis through television and radio. However, information on disaster prediction cannot be received if televisions or radios at homes are not turned on even if this information is promptly and properly transmitted. Therefore, it is necessary to transmit control signals for emergency warnings on broadcasting waves, which will automatically turn on home receivers when emergency earthquake or tsunami information must be promptly sent.

NHK Science and Technology Research Laboratories started to research and develop a broadcasting system to achieve this objective in 1979 that could ensure code signals for emergency warnings were received and home receivers were turned on [1][2]. Broadcasting stations sent code signals for emergency control before programs on emergency warnings were broadcast with this system of broadcasting code signals for emergency warnings, and the receivers dedicated to this system would always be waiting for these code signals that controlled emergency warnings. When the code signals were detected, the receivers turned on radios or televisions so that people could listen to or watch emergency programs.

NHK achieved this objective by using frequency shift keying (FSK) code signals that were theoretically and rigorously selected to obtain remarkably high reliability. The Japanese Government adopted the technologies for the system of broadcasting the code signals for emergency warnings as a national technical standard. NHK began the operation of this system on September 1, 1985[3] following the directives of the Prime Minister, who responded to a request by the Governor of Shizuoka Prefecture in the Tokai area. NHK currently broadcasts test code signals for emergency warnings before noon on the first day of every month, to ascertain whether the receivers of code signals for emergency warnings are functioning. The historical significance of the development and operation of this system is fourfold.

1. The system broadcasts codes that do not include ordinary information, such as sounds, images, or data.

2. The target of the system is not people, but machines (receivers dedicated to this system).

3. The system is directly related to broadcasting that conveys very important information regarding people’s lives and demise.

4. The system is remarkable and extremely reliable. When there are no code signals for emergency warnings, it will not malfunction because of program sound and noise, and when the code signals for emergency warnings are transmitted, the receivers will function without failures of any kind.

This is a completely unique, exceptional, and incomparable system, which is sure to be recorded in the history of broadcasting technology. Secure and prompt transmission of emergency information to the home, such as predictions of large-scale earthquakes and tsunamis, has been achieved due to this system that broadcasts code signals for emergency warnings.

The first actual broadcast of the code signals occurred on March 18, 1987. This was for a tsunami warning after an earthquake had occurred in the Kyushu area. The code signals of the broadcasting system have been transmitted 22 times thus far, and have helped and saved many people’s lives. The dedicated receivers, and conventional radios and TVs with the circuits for receiving the code signals of emergency warnings installed are continuously being sold. The Fire and Disaster Management Agency, which is in charge of disaster relief, recognized the system’s importance and is actively promoting it. Furthermore, this system of broadcasting code signals for emergency warnings became well-known to the world when a M 9.1 earthquake struck and a large-scale tsunami in its aftermath occurred off Sumatra in December 2004, which caused a great deal of damage and inflicted many casualties.

The system was adopted as an International Telecommunication Union (ITU) recommendation in 2007 [4][5], and was published in the Asia-Pacific Broadcasting Union (ABU) technical handbook in 2008 [6].

In this digital era, the EWBS standardization activity for digital terrestrial television is also promoted. In order to harmonize the implementation processes among countries adopting ISDB-T, the “ISDB-T International Forum” was organized. As of 2013, there are 13 countries participating: Argentina, Bolivia, Botswana, Brazil, Costa Rica, Chile, Ecuador, Paraguay, the Philippines, Peru, Uruguay, Venezuela and Japan. The document for EWBS implementation is published and widely accepted [7].

What obstacles (technical, political, geographic) needed to be overcome?

The system for broadcasting code signals for emergency warnings must activate dedicated receivers to turn on conventional radios and TVs to ensure that people promptly listen to and watch programs on emergency broadcasts even if reception is poor or they experience severe conditions. As the warning control code signals are transmitted through broadcasting paths, program sound and noise interferes with the dedicated receivers. Thus, the system must meet four requirements:

A) The dedicated receiver of this system must not operate erroneously as a result of broadcasting program sound signals or accompanying noise (zero malfunction),

B) It must operate without failures even under severe receiving conditions when the code signals for emergency warnings are transmitted (secure operation),

C) It must be extremely reliable and consume limited amounts of power because it must always be on stand-by for warning signals, and

D) It has to be activated quickly (It is very difficult to satisfy both A) and B) since they conflict in some cases).

Frequency shift keying the code signals based on digital technology is used to meet these requirements. The most important thing is the selection of code patterns to prevent malfunctions. The probability of program sound or noise matching the control code signal decreases exponentially as the code length increases. A code length of 64 bits makes the probability of signals matching almost zero. A longer code, on the other hand, lowers the probability of precise reception as a result of noise and interference in the transmission path. Therefore, it was decided that a code length of 16 bits be used as the basic fixed code and that by receiving the fixed code four times, an equivalent reception of 64 bit code would be achieved, which meant there were no malfunctions. The pattern of the fixed code was carefully selected so that it did not match the program sound and noise, and allowed word synchronization. It was also separated from other code patterns to avoid matching other codes so that the same pattern as the fixed code was formed when using the variable code, which will be described later. The FSK control signals were selected in the middle range of the audio frequency, i.e., 640 and 1024 Hz, at a bit-rate of 64 bit/s, so that they could be transmitted by any broadcasting media as a warning sound, which is now familiar to most people living in Japan.

The second requirement was to quickly activate the dedicated receiver. The receiver in conventional digital transmission systems sets the clock up first and then the signals are detected. Setting up the clock takes time. As it was necessary to convey the emergency information to people as quickly as possible, an electronic circuit was invented that could immediately detect the broadcasting signals for emergency warnings. This circuit found the matching codes by examining incoming code patterns bit by bit using an independent synchronization in the receiver. Inexpensive crystal oscillators used in ordinary watches were used for this purpose. They could detect code signals for emergency warnings within a very short time without the clock set-up code or the set-up procedure.

Field tests demonstrated that medium frequency waves could be transmitted beyond 1,000 kilometers with a fading phenomenon at night, and through ionosphere reflections. This indicated that receivers located in remote areas that did not need to receive particular programs on emergency warnings might be turned on. This problem was solved by adding an area classification code.

This system also had to be able to deal with circumstances in which terrorists recorded the control signals. They can turn on receivers by using recorded control signals, break into conventional broadcasting waves, and broadcast their own information. A time classification code containing the year, month, and day was also transmitted as a counter measure against such malicious acts. The receiver only turned on when its clock matched the time classification code. This eliminated the chance of terrorists taking over broadcasts.

There are two kinds of control signals, i.e. a start and an end signal. The start signal denotes the beginning of the program to broadcast emergency warnings and activates equipped receivers [5]. The end signal denotes the end of the program to broadcast emergency warnings and the activated receiver returns to its original state.

The start and end signals are basically composed of fixed codes and classification codes which are 16 bit code words. Fixed code is the most important in the early warning broadcasting system (EWBS) control signal. The classification code carries additional information such as area and time classifications. The basic unit is 96-bit length, which consists of three fixed codes, i.e., the area classification, the month-date classification, and the year-time classification codes.

Furthermore, each fixed code is accompanied by a kind of specified classification code, which takes 1.5 s. The start signal usually repeats the 96-bit length unit ten times to ensure reliable reception. The end signal usually repeats the 96-bit length unit and 92-bit length of the no-signal period four times[8].

What features set this work apart from similar achievements?

There are various methods of multiplexing the control signals with radio and television sound.

The Emergency Broadcast System (EBS) used from 1963 to 1997 in the U.S.A. was a similar broadcasting system. EBS was a tone signal system that used two kinds of sound frequencies. The EBS’s signal was a combination of the sine waves of 853 and 960 Hz to obtain the audience's collective attention.

The tone signal system was used earlier because it was theoretically simple. However, it was prone to errors when the signal frequencies of the broadcasting programs were the same as the tone signals. It was therefore necessary to distinguish them from the program sound by sending out tone signals for a sufficiently long time to ensure operation. It was also not appropriate to operate receivers in restricted regional areas for emergency warning broadcasts.

The system we propose of broadcasting code signals for emergency warnings is extremely reliable. That means these described measures ensure secure operation and zero malfunctions because it uses FSK with two frequencies in the middle band of sound and the code pattern is meticulously and rigorously selected. It can convey emergency information exclusively to areas that need the information, and take on anti-hijacking measures by adopting area classification codes and time classification codes. The control code signals can be transmitted on all broadcast media such as AM radio, FM radio, or television.

Conventional digital systems require clock set-up codes for clock set-ups that take too long. However, this proposed system can promptly turn on receivers with independent bit synchronization using an inexpensive crystal oscillator. That means it can activate receivers quickly because it uses digital technology without the need for clock set-ups.

The system is extremely reliable and inexpensive. It does not malfunction, operates without failures, and conveys urgent emergency information to people promptly when they need it.

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.

1.Seiichi Namba, “A New Approach to the Design of Receiver Control Code for Broadcasting System - An application to the regional code of emergency broadcasting system-”, The Technical Report, The Institute of Television Engineers, May 27, 1982 (See Attached file).

2. Seiichi Namba and Hisakichi Yamane, “Attention Signal System for Emergency Alert Broadcasting”, NHK Laboratories Note, No.268, January 1982, (See Attached file)

3.The chronological table of “20th Century Broadcasting History (On NHK in August and September, 1985)”,Edited by Japan Broadcasting Corporation (NHK), Nippon Broadcasting Publishing Corporation, 2001 (See Attached file).

4. Kazuyoshi Shogen, Yasuhiro Ito, Hiroyuki Hamazumi and Makoto Taguchi,“Implementation of Emergency Warning Broadcasting System in the Asia Pacific Region”, ITU/ESCAP Disaster Communications Workshop, 12 – 15 December 2006, Bangkok, Thailand[NHK]%20Dr%20Kazuyoshi%20SHOGEN.pdf

5. RECOMMENDATION ITU-R BT.1774-1, “Use of satellite and terrestrial broadcast infrastructures for public warning, disaster mitigation and relief”, 04/2007!!PDF-E.pdf

6. HANDBOOK ON EWBS (-Emergency Warning Broadcasting System-), Technical Committee, Asia-Pacific Broadcasting Union, 2008

7. ISDB-T harmonization document, part 3: Emergency Warning Broadcast System, 2013

8. Jyunichi Ishida, et al. "BROADCAST AND NEW MEDIA", pp.249-256, Maruzen Advanced Technology,1992, (See Attached file)

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 Please see the Milestone Program Guidelines for more information.

-1- ITE_Report_RE82-13_pp33-38_English.pdf

-2- NHK Laboratories, Note No. 268, January 1982.pdf

-3- EWBS_launched_description.pdf




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 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 Please include the docket number and brief title of your proposal in the subject line of all emails.

-1- ITE Report RE82-13 pp33-38 English.pdf
-2- NHK Laboratories, Note No. 268, January 1982.pdf
-3- EWBS launched description.pdf
EWBS overview.pdf
Chroological record EWBS NHK.pdf