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Services Diversify

1978  Experimental sound multiplex TV broadcast begins
1985 Regular teletext broadcasting using hybrid system begins
1985 Emergency Warning System begins operation
1986 CCIR adopts Japanese teletext system as a new recommendation
1986 Commercial broadcasters begin FM multiplex broadcasting services for fixed reception
1994 FM multiplex broadcasting for mobile reception (text data service) begins
1995 FM multiplex broadcasting "DARC" recommended at the ITU-R
1996 VICS Center begins traffic information service using FM multiplex broadcasting

The technology for diversifying broadcast services had progressed. Research on stereophonic broadcasting began in 1952, followed by studies on sound multiplex TV broadcasting. In 1978, bilingual broadcasts were introduced amidst a wave of initiatives aimed at "internationalization". Advancements were also made in the field of teletext broadcasting, which was later combined with digital technology, to create a new data broadcasting service.

1980-90 The Arrival of New Media

The Potential to Receive Direct Satellite Broadcasts in the Home

Satellite broadcasting requires a small antenna and a high-sensitivity receiver in addition to the actual broadcasting satellite. Conventional satellite communications prior to this period had employed receiving antennas ranging in size from several to dozens of meters in diameter, far too large for home use. Home reception of satellite broadcasts required a low-price, high-sensitivity receiver in conjunction with increased output from the satellite. STRL devised receiver comprised of a planar circuit mounted in a waveguide that utilized a small, inexpensive, yet highly-sensitive antenna.

Path to Implementation

After various preparations were completed regarding channel assignment, receivers, etc., Japan's first broadcasting satellite BS was launched atop a U.S. Delta Rocket on April 8, 1978.

In 1979, the decision was made to launch two satellites (BS-2a, BS-2b), allowing backup satellites to carry out practical broadcasting on two channels. They were launched on domestically manufactured N-2 rockets.

In order to extend usable life, while retaining the same scale as the BS satellite, the new satellites switched to helix-type TWTs, which are half the weight of the coupled-cavity-type TWTs used in the original BS satellite. After integration of the results of research from the original BS satellite, BS-2a was launched from Tanegashima Island in January 1984.

Unfortunately, two of the TWTs failed within several months of the launch, so the scheduled satellite broadcast was quickly changed to a test broadcast on a single channel. Immediate measures were taken to determine the cause of the TWT failure and to create countermeasures. After a test broadcasting period, regular satellite broadcasting commenced on two channels using the BS-2b, which was launched in February 1986.

The experience gained through the BS-2a satellite program was later applied to ground-based space environment tests on TWTs. Consequently, domestic TWTs were installed in BS-3a and BS-3b, launched in 1990 and 1991 respectively.

STRL's broadcast satellite research began in 1966, and their findings were passed on to the Broadcasting Satellite System Corporation (B-SAT). Currently, five satellites, BSAT-1a, 1b, 2a, 2c, and 3a reach viewers in over 20 million households, providing satellite broadcasts across 12 digital and three analog channels.