Teletext reception indicator

• US 4,520,392 A
• Filed: 03/04/1983
• Issued: 05/28/1985
• Est. Priority Date: 11/23/1981
• Status: Expired due to Fees

• Current Assignee: Zeith Electronics Corporation
• Original Assignee: Zenith Electronics Corporation (LG Corporation)
• Inventors: Cox, Charles M., Heuer, Charles
• Primary Examiner(s): Martin, John C.
• Assistant Examiner(s): Harvey, David E.
• Application Number:
  US06/471,978
• Time in Patent Office: 816 Days
• Field of Search: 358/142, 358/147, 358/192.1, 358/257
• US Class Current: 348/468
• CPC Class Codes: H04N 21/47 End-user applications
• CPC Class Codes: H04N 21/4888 for displaying teletext characters
• CPC Class Codes: H04N 5/44504 Circuit details of the additional information generator, e.g. details of the character or graphics signal generator, overlay mixing circuits
• CPC Class Codes: H04N 7/0882 for the transmission of character code signals, e.g. for teletext circuits for the digital non-picture data signal H04N7/035

Abstract

An indicator is described for alerting a television viewer to the fact that a teletext signal is being received. In the preferred embodiment, the indicator includes a control which senses the detection of the framing code associated with the received teletext signal to actuate an indicator lamp.

Claims

1. For use with a teletext decoder which decodes teletext signals having a framing code, a teletext indicator, comprising:

control means associated with the teletext decoder and responsive to the decoder'"'"'s detection of a framing code for generating a control signal, said control means being responsive to vertical rate gate pulses for resetting the control signal; and

indicating means responsive to the control signal for indicating the receipt of a valid teletext signal.

2. A teletext indicator as set forth in claim 1 wherein said control means includes first gate means responsive to framing code data developed by the decoder for generating a first output, and second gate means responsive to said first output for developing a second output signal indicative of the receipt of a teletext signal and responsive to vertical rate gate pulses for resetting the second output signal.

3. A teletext indicator as set forth in claim 2 wherein said first gate means is enabled by a window signal which occurs concurrently with a valid framing code.

4. A teletext indicator as set forth in claim 1 further including means for latching the control signal in response to the vertical rate gate pulses to develop a further signal useful for automatically actuating recording of teletext data.

5. For use with a teletext decoder which decodes teletext signals having a framing code, a teletext indicator comprising:

control means comprising first counting means responsive to the detection of N framing codes by the teletext decoder for initiating a control signal and second counting means responsive to N vertical rate gate pulses developed immediately following the generation of a control signal for resetting the control signal; and

indicating means responsive to the control signal for indicating the receipt of a valid teletext signal.

6. For use with a teletext decoder which decodes teletext signals having a framing code, a teletext indicator, comprising:

a gate for sensing the decoder'"'"'s detection of a framing code;

means for applying to said gate a window enable signal which occurs concurrently with a valid framing code, thereby to provide a first output signal corresponding to a windowed framing code;

a first flip-flop responsive to said first output signal for developing a control signal;

means for resetting the flip-flop at a vertical rate; and

means responsive to the control signal for indicating the receipt of a valid teletext signal.

7. For use with a teletext decoder which decodes teletext signals having a framing code, a teletext indicator comprising:

a gate for sensing the decoder'"'"'s detection of a framing code;

means for applying to said gate a window enable signal which occurs concurrently with a valid framing code, thereby to provide a first output signal corresponding to a windowed framing code;

a first flip-flop responsive to said first output signal for developing a first control signal;

means for developing a vertical rate gate signal;

means for resetting said first flip-flop at a vertical rate in response to said vertical rate gate signal;

first counting means responsive to the development of N first control signals for developing a second output signal;

a second flip-flop responsive to said second output signal for developing a second control signal;

second counting means enabled by said second control signal for counting N vertical rate gate signals for developing a reset control signal coupled for resetting said second flip-flop; and

means responsive to the second control signal for indicating the receipt of a valid teletext signal.