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APF (All Plastic Fiber) has high transmission loss and it is a disadvantage in the optical communication. If it has been used in an optical network with distributed signals, like star type, optical signals are reduced at the star coupler due to scattering loss and insertion loss caused by ray distribution. Therefore, we can use a passive star coupler only in a small area. One possible solution is light amplification at the optical star coupler using a feed back method. The feed back amplifier is composed of a pair of E/O (Erectrical/Optical), O/E (Optical/Electrical) converters using one channel in the passive star coupler. It has a performance that is able to increase the output level about 3dB at each output port. So, it enables communication between nodes with certainty. We named ACTIVE STAR COUPLER.

We were the first in the world to start mass-producing the fiber optic gyroscope for an automobile navigation system. The fiber optic gyroscope was installed in an automobile in order to improve position detection accuracy. However, mass-producing the fiber optic gyroscope for an automobile navigation system was not possible before because it was difficult to achieve the high performance required under many operating conditions, especially in wide temperature ranges between -20 °C∼70°C. In order to overcome these problems, we have developed a new signal processing for a fiber optic gyroscope having the compensation functions of cancelling the fluctuation of the optical signal. The navigation system using this gyroscope has been installed in the Nissan Motor Company's 1991 CEDRIC, GLORIA, and CIMA models.

This paper describes an Automobile Navigation System with Multi-Source Guide Information. One of the features of this system is accurate location detection, which uses refined map-matching method incorporating a high accuracy rotation sensor, Fiber Optic Gyroscope (FOG). The system shows the position of the vehicle on a CRT map display and can also provide useful information, such as the locations of hotels, golf courses, etc., by using a CD-ROM disc. In addition to this information, this system can play CD-ROM discs based on the CDCRAFT standard. By means of this standard, software vendors can produce multimedia entertainment, such as a sightseeing guide with voice. Also, this system can display road and traffic information from the roadside radio beacons of the Vehicle Information & Communication System (VICS). This navigation system has been installed in Nissan's 1991 model Cedric, Gloria and CIMA.

The recently developed navigation systems discussed in this paper include location detection using map-matching, map display, and improved man-machine interface functions, and are contained in a stand-alone system installed in passenger cars. The newest system uses a fiber optic gyroscope as a rotation rate sensor, and improved map-matching method to get high accuracy. As to driving guide information, the system can display road information from road side radio beacons, and can play CD-ROM discs based on CDCRAFT which is proposed in Japan as a common standard of CD format and application program for navigation systems.

The wheel rotation sensor developed for navigation system is small and light, and generates high output voltage of 0.37V p-p without a prc-amplifier when the gap between the sensor and the multi-polarized magnetic rotor is 2.0mm. The sensor has excellent resistance to environmental conditions. Several simulation tests and car evaluations were carried out and it is confirmed that the sensor generates enough output voltage and satisfies requirements for the system including the decrease of output voltage caused by temperature, gap variation while running, and so on.

An optical receiver IC for fiber-optic data links has been developed for use in multiplex wiring harnesses. This IC consists of a PD (Photodiode), a transimpedance, an amplifier, and a comparator to be compatible with TTL. A PD and these circuits are all integrated into one chip, the size of which is 3 mm square, by using the Si-bipolar process. It is hermetically sealed in a can package. It operates at a data rate up to 1 Mbps (Mbps = 106 bits per second). It also has no requirement of sensitivity adjustment for its wide dynamic range (25 dB).