Digital signal transmitting and/or receiving system

• US 4,656,629 A
• Filed: 11/06/1984
• Issued: 04/07/1987
• Est. Priority Date: 11/09/1983
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kondoh, Yoshiyuki, Ishidoh, Takanobu
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Scutch, III, Frank M.
• Application Number:
  US06/668,794
• Time in Patent Office: 882 Days
• Field of Search: 370/85, 370/110.2, 370/110.3, 370/110.1, 455/4, 455/6, 358/86, 358/141, 358/142, 358/143, 358/145
• US Class Current: 370/522
• CPC Class Codes: H04H 20/59 for emergency or urgency
• CPC Class Codes: H04H 20/79 using downlink of the CATV systems, e.g. audio broadcast via CATV network
• CPC Class Codes: H04H 60/15 on receiving information
• CPC Class Codes: H04H 60/16 on playing information
• CPC Class Codes: H04H 60/23 using cryptography, e.g. encryption, authentication, key distribution
• CPC Class Codes: H04J 3/1605 Fixed allocated frame structures
• CPC Class Codes: H04N 7/16 Analogue secrecy systems; Analogue subscription systems

Abstract

A digital signal transmitting system includes a signal generator for producing time division-multiplexed digital audio signals and service bit signals, a modulator for modulating a carrier in accordance with the time division-multiplexed signals and a transmitter to transmit the modulated carrier through a CATV (cable television) transmission line. In a receiver, the service bit signals are decoded so as to control the channel changeover of a television receiver when an emergency broadcast signal is transmitted. A muting control circuit is also provided so as to mute an audio signal from a D/A (digital-to-analog) converter.

Claims

1. A digital signal transmitting system comprising:

means for generating a word synchronizing signal;

means for generating digital audio signals sampled at a sampling frequency and coded in a predetermined data length;

means for generating service bit signals including an identifying signal indicating that an emergency broadcast signal is being transmitted;

means for mutiplexing said word synchronizing signal, digital audio signals and service bit signals so as to produce a digital word signal;

a cable television transmission line; and

means for modulating a carrier in accordance with said digital word signal and transmitting the modulated carrier through said cable television transmission line.

2. A digital signal transmitting system according to claim 1, in which said digital audio signals include at least a 2 channel stereo broadcast signal and an emergency broadcast signal.

3. A digital signal receiver comprising:

a signal input terminal for receiving a modulated carrier modulated by a time-multiplexed word synchronizing signal, digital audio signals and service bit signals, said service bit signals including an identifying signal indicating than an emergency broadcast signal is being transmitted;

means for demodulating said time division-multiplexed word synchronizing signal, digital audio signals and service bit signals;

a speaker,

an audio amplifier connected to said speaker;

means for digital-to-analog-converting said digital audio signals into analog signals which are supplied to said speaker through said audio amplifier;

a television receiver connected to said signal input terminal so as to receive a plurality of channels;

means for latching said service bit signals; and

control means connected to said latching means so as to produce a control signal which is supplied to said television receiver to turn on said television receiver when said identifying signal is received.

4. A receiver according to claim 3, in which the channel of said television receiver is changed over by said control signal from said control means to receive a predetermined channel.

5. A receiver according to claim 4, in which said predetermined channel receives said emergency broadcast signal.

6. A receiver according to claim 3, in which said control means comprises a microcomputer.

7. A receiver according to claim 3, in which said control means produces a muting control signal which is used to prevent an analog signal from being transmitted to said speaker.