Pioneer Electronic Corporation

Sumitaka Matsumura

Yoshiaki Moriyama

Masaki Saito

Tsuyoshi Fujiwara

Yoshifumi Saeki

Saburo Takaoka

Minoru Kosaka

Hiroki Uemura

Tsutomu Suzuki

Tsutomu Fukui

Youichiro Tsuda

Akihiro Ono

Toshio Gotoh

Kaname Abe

Seiji Hashimoto

Shozo Nakamuta

Kenji Yamagata

Takashi Morii

Toshihiko Hosaka

Tetuo Kanazashi

Osamu Tazawa

Kuniaki Shiratori

Morihisa Oka

Katsuaki Matsumoto

A digital television circuit in which the analog FM video signal is first digitized and all processing is performed digitally, including FM demodulation. Clocks at the subcarrier frequency and four times this frequency are synchronized with the horizontal synchronizing circuit or color burst signal.

Fully digitized video signal reproducing apparatus

An FM detector includes a Hilbert transforming means and a pair of detector circuits which respectively detect an input FM signal and a Hilbert transform of the input FM signal produced by the Hilbert transforming circuit. Output signals of the two detector circuits are applied to a combining circuit, such as an adder circuit, to provide a detection output signal. With this construction, a second harmonic component which is inevitably produced during the detection operation is cancelled, so that a detector output signal, free of the so-called Aliasing distortion, is obtained even if an overlap between the baseband component and the second harmonic component occurs. Further, the gain characteristic of the detector is greatly improved.

FM detector with improved distortion and gain characteristics

A two-way CATV system having a substantial number of terminals incorporates a central processor and transmitter system which continually interrogates the terminals at high speed, monitoring changes of usage of premium programs and other data while also permitting central control of access to restricted premium programs. For inexpensive but reliable intercommunication, short, fixed word length digital messages are frequency multiplexed onto the cable in both upstream and downstream directions, and subscriber groups are controllably selected in turn, with each subscriber being scanned in what may be an arbitrary order by transmission of unique private messages which are recognized at the terminal and in response to which previously prepared fixed length messages are immediately transmitted in return. By employing both upstream and downstream messages which are initiated by a series of synchronizing bits and non-ambiguously related subsequent data sequences, and by the provision of means to initiate both downstream and upstream messages of short length without delay, rapid but reliable data interchange is effected despite differences in transmission and response times with different subscribers. Concurrently, terminal status and various special conditions including security alarms are remotely processed at each terminal, and short upstream messages are assembled containing priority selected data to be transmitted in response to an interrogation. The system incorporates additional means for monitoring power status, program selection and authorization and other operating conditions at each terminal effectively to provide accurate and reliable accounting information while preventing unauthorized or improper usage of restricted premium programs.

Interactive CATV system

Growing community of inventors

Tokorozawa, Japan

Sumitaka Matsumura