Milestones:Emergency Warning Code Signal Broadcasting System

From IEEE Milestones Wiki

This is a temporary page. The final version of this page can be found on the Engineering and Technology History Wiki


Emergency Warning Code Signal Broadcasting System, 1985


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.

Street address(es) and GPS coordinates of the Milestone Plaque Sites

35.6356483, 139.6157232, 1-10-11 Kinuta,Setagaya, Tokyo 157-8510 Japan

Details of the physical location of the plaque

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 the intended plaque site is protected/secured

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.

Historical significance of the work

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].

Features that 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.

Significant references

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

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

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

-3- EWBS_launched_description.pdf