Communication method and equipment for freeze-frame video phone

• US 5,199,061 A
• Filed: 01/16/1992
• Issued: 03/30/1993
• Est. Priority Date: 09/06/1989
• Status: Expired due to Term

• Current Assignee: Electronics and Telecommunications Research Institute, Korea Telecommunication Authority
• Original Assignee: Electronics and Telecommunications Research Institute, Korea Telecommunication Authority
• Inventors: Kim, Do Young
• Primary Examiner(s): Dwyer, James L.
• Assistant Examiner(s): Chan, Wing F.
• Application Number:
  US07/823,029
• Time in Patent Office: 439 Days
• Field of Search: 379/53, 379/54, 379/96-98, 379/100, 375/34, 375/58, 375/121, 371/5.5
• US Class Current: 348/14.14
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0014 by adapting the source coding
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04N 1/33307 prior to start of transmission, input or output of the picture signal only
• CPC Class Codes: H04N 2201/33371 using test signals, e.g. checking error occurrences
• CPC Class Codes: H04N 7/147 Communication arrangements, e.g. identifying the communication as a video-communication, intermediate storage of the signals selecting H04Q

Abstract

The present invention comprises a system bus performing control and data transmission function among modules, a system control means, connected to the system bus, performing system control and interrupt control function, a modem and DTMF signal processing means, connected to the system bus, performing modulation and demodulation in the transmission rate of 9,600 bps, 4,800 bps, and 2,400 bps, and transmission and reception of DTMF signal, a standard telephone line connection means connecting the modem and DTMF signal processing means and a telephone to a standard telephone line, a program ROM, connected to the system bus, storing a program which controls communication through the modem and DTMF signal processing means, and a RAM, connected to the system bus, retaining current data.

Claims

1. A method for sending and receiving freeze-frame video information, the method comprising:

a first step for sending a video control tone signal consisting of five dual tone multifrequency (DTMF) signals for forming three fields comprising a first field of two DTMF tones which contains a signal indicating a start of video data communication, a retransmission signal after deceleration of a transmission speed, and a signal indicating the transmission of video data, a second field of a DTMF tone which indicates said transmission speed, and a third field of two DTMF tones which contains information regarding color of the video data, size of the video data, and type of a character data;

a second step for receiving in one field among said three fields an Acknowledge ("ACK") signal or a Negative Acknowledge ("NAK") signal from a receiving side in response to said first step;

a third step for sending a plurality of binary "0" signals according to the transmission speed of said second field when said ACK signal of said second step has been received; and

a fourth step for sending the video data at the transmission speed when said ACK signal has been received in response to said third step, and for restarting from said first step after reducing the transmission speed sequentially from 9.6 kbps to 4.8 kbps and then to 2.4 kbps in case said NAK signal has been received after performing said third step.