United States Patent [19]
Sugie
[11] Patent Number: 4,519,081 [45] Date of Patent: May 21, 1985
[54] FACSIMILE COMMUNICATION METHOD WITH ANTI-ECHO STRATEGY
[75] Inventor: Masatoshi Sugie, Zama, Japan
[73] Assignee: Ricoh Co., Ltd., Japan
[21] Appl. No.: 393,304
[22] Filed: Jun. 29, 1982
[30] Foreign Application Priority Data
Jun. 29, 1981 [JP] Japan 56-102063
[51] Int. CI.3 H04M 1/36
[52] U.S. CI 371/57; 371/47;
358/257
[58] Field of Search 364/200, 900; 371/57,
371/47; 358/257, 256, 264
[56] References Cited
U.S. PATENT DOCUMENTS
3.441,665 4/1969 Wuensch 358/257
3.914.537 10/1975 Perreault et al 358/257
4.000,371 12/1976 Ogawa 358/257
4,296,439 10/1981 Teramura et al 371/57
4,296.440 10/1981 Rosenheck 358/257
Primary Examiner—Jerry Smith
Assistant Examiner—Michael R. Fleming
Attorney, Agent, or Firm—Guy W. Shoup
[57] ABSTRACT
In a facsimile communication method capable of preventing receipt of an echo of data being transmitted, a preamble-preceded frame is used as a data to be transmitted, and the frame is allowed to be received only when its preceding preamble has been received. For this purpose, the total time length of the preamble-preceded frame being transmitted is monitored. If it is shorter than a predetermined time length, a number of flags as required are added to the end of preamble-preceded frame, thereby ensuring that the total time length of transmitting the data is always longer than the predetermined time length. In this manner, it is ensured that an echo of data being transmitted returns only while transmission of the data is in progress and is thus not received.
5 Claims, 12 Drawing Figures
