Tuning system for CATV terminal

• US 4,317,215 A
• Filed: 09/11/1979
• Issued: 02/23/1982
• Est. Priority Date: 09/13/1978
• Status: Expired due to Term

• Current Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Original Assignee: Pioneer Electronics (USA) Incorporated (Pioneer Corporation)
• Inventors: Uemura, Hiroki, Tabata, Toshio
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): Chin, Tommy P.
• Application Number:
  US06/074,486
• Time in Patent Office: 896 Days
• Field of Search: 455/2, 455/3, 455/4, 455/5, 455/6, 455/169, 455/184, 358/84, 358/86, 358/117, 178/63 F
• US Class Current: 725/131
• CPC Class Codes: H04N 7/16 Analogue secrecy systems; Analogue subscription systems
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications

Abstract

In a CATV system, channel identifying data is incorporated in each transmitted channel, and subscriber terminals return such data to the CATV center to indicate the channel actually being received. Further, the channel identifying data is compared to the channel selected, and when a proper comparison exists a sweep voltage is held at a predetermined level for the particular channel, to control frequency conversion at the terminal.

Claims

1. In a tuning system of a CATV terminal having an electronic tuning converter which in response to a tuning voltage converts a desired channel from TV signals containing separate channel identifying data on each channel and transmitted downstream from a CATV center into a specific channel frequency which is provided as an output, the improvement comprising a channel signal separating circuit connected to receive the output of the converter and extract the channel identifying data contained in a converted channel, a circuit coupled to receive the extracted channel identifying data from the channel signal separating circuit and transmit the channel identifying data to the CATV center, a data comparing circuit connected to compare channel selecting data obtained from a channel selecting device with said extracted channel identifying data and generate a holding signal when said two data coincide, a sweep signal generating circuit for generating a sweep signal in a voltage range capable of selecting all channels of said TV signals, and a voltage holding circuit which, while ordinarily passing said sweep signal therethrough, holds a voltage of said sweep signal in response to the holding signal and supplies said held voltage to said electronic tuning converter as said tuning voltage.

2. A CATV tuning system comprising:

a channel selecting device providing as an output an indication of a desired channel;

a channel signal separating circuit coupled to receive a tuned TV channel from the output of a tuning circuit and to output tuned channel information derived from and indicative of the tuned TV channel;

a data comparing circuit coupled to receive as inputs the output of the channel selecting device and the tuned channel information and to generate at an output a voltage holding signal when the desired channel indicated by the output of the channel selecting device is the same as the tuned TV channel indicated by the tuned channel information;

a sweep signal generating circuit generating a sweep signal;

a voltage holding circuit coupled to receive the sweep signal and the output of the data comparing circuit, the voltage holding circuit providing as an output to a tuning circuit a tuning voltage which is responsive to the sweep signal and has a voltage range capable of causing a tuning circuit to tune all available CATV channels, the tuning voltage being held constant during receipt of the voltage holding signal from the data comparing circuit; and

a circuit coupled to receive the tuned TV channel information from the channel signal separating circuit and transmit the tuned TV channel information to a CATV center.