Abstract: A system for reducing noise in a signal line, through which upward signals and downward signals are transmitted between a center and terminals, includes a noise-reduction device provided between the center and the terminals. The noise-reduction device attenuates the upward signals by an increased amount when a noise increase regarding the upward signals is detected on the signal line. The system further includes a noise-control device, provided at terminals, which boosts a transmission level of the upward signals by an amount compensating for the attenuation of the upward signals by the noise-reduction device.

Abstract: The present invention concerns an ingress noise control system and an ingress noise blocking device which are used in a cable system to suppress ingress noise. In the cable system providing two-way communication using different frequency bands for transmission of upstream and downstream signals, the ingress noise control system includes, within a distribution unit, a two-way amplification unit, etc. provided in an upstream signal transmission path, a synchronous detection controller 6 for synchronously detecting the upstream signal transmitted from terminal equipment and separated by a low-pass filter 4 in a second separation filter 2, a gate switch circuit 5 which is turned on by the synchronous detection controller 6 to pass the upstream signal only when the upstream signal is synchronously detected, and an indicator 7 for indicating the on/off state of the gate switch circuit 5.

Abstract: A CATV transmission center apparatus, a subscriber terminal device, a CATV distribution system, and a method of distributing a program, will solve the problems of the need to change transmission facilities for handling more channels, the costly CATV infrastructure per program, the expensive subscriber terminal devices, and the tedious and time-consuming process of selecting desired programs. When there is a request to view a program which is not being distributed from the subscriber terminal device to the CATV transmission center apparatus, an empty channel is searched for. If an empty channel is found, the requested program is distributed via the empty channel. All subscriber terminal devices are notified that the program which has started to be distributed is being distributed. The CATV transmission center apparatus distributes only those programs which are actually viewed by subscribers.

Abstract: A picture signal transmitting system using a CATV network sends a picture signal from a transmission path to subscribers by using a radio transmitter and receiver, and in the picture signal transmitting system, there is no physical wire connection from a tap off of the transmission path to subscribers.

Abstract: In a hybrid SCM optical transmission apparatus, and particularly in a hybrid SCM optical transmission apparatus which performs transmission by modulating laser light by a hybrid signal formed by frequency multiplexing an analog-modulated signal with a digitally modulated signal to form a hybrid AM-QAM signal, for the purpose of both effective utilization of transmission bandwidth and reduction of clipping deterioration, a signal limiting section which applies limiting to the analog-modulated signal is provided, frequency-division multiplexing being done of analog-modulated signal output from this signal limiting section and a digitally modulated signal.

Abstract: An optical drop-and-insert apparatus which can process an optical signal in the form of an optical signal without converting the optical signal into an electric signal. The optical drop-and-insert apparatus expands the pulse width of an optical data pulse in an optical data pulse train on an optical highway and drops the optical data pulse to form an empty bit at the bit of the optical data pulse or another bit so that a new optical data pulse may be inserted into the empty bit. Miniaturization of the apparatus and increase in processing speed can be attained by enabling processing of an optical signal while it remains in the form of an optical signal.

Abstract: An optical switching system receives an optical input signal which is a wavelength-division multiplexed and time-division multiplexed signal. The optical input signal is divided into time-division multiplexed optical signals in different wavelength regions and transferred within an optical data bus after being subjected to a predetermined process including a frequency shift. The optical signals in the different wavelength regions are extracted from the optical data bus using optical bandpass filters, and multiplexed into an output optical signal which is a wavelength-division multiplexed and time-division multiplexed signal after being subjected to a predetermined process including a frequency shift.

Abstract: A fiber-optic gyro includes a laser diode, a light detector, first and second lenses arranged on both sides of a half mirror, and a coil-like optical fiber which is arranged so that the two ends of the optical fiber confront the first and second lenses, respectively. Light from the laser diode is incident on the half mirror through the first lens, the light reflected from the half mirror is incident from one end of the coil-like optical fiber through the first lens, and the light transmitted through the half mirror is incident from the other end of the coil-like optical fiber through the second lens. Therefore the light is propagated through the coil-like optical fiber in opposite directions, light from the coil-like optical fiber is synthesized and is incident on the light detector, and the speed of the rotation angle is detected by the output of the light detector.