Picture communication systems

Claim 1

PICTURE TRANSMISSION SYSTEM COMPRISING MEANS FOR TRANSMITTING SEQUENTIAL SIGNALS REPRESENTING THE LINES OF A SELECTED FIELD OF AN INTERLACED TWO-FIELD SCAN, MEANS FOR RECEIVING SAID SIGNALS, MEANS FOR PERFORMING AN INTERPOLATION BETWEEN SUCCESSIVE LINES OF SAID FIELD TO PROVIDE SIGNALS REPRESENTING AN APPROXIMATION TO THE LINES OF THE UNSELECTED FIELD, SAID LAST-MENTIONED MEANS COMPRISING STORAGE MEANS FOR STORING SUCCESSIVELY AT LEAST TWO LINES OF PICTURE SIGNAL, MEANS FOR SCANNING AT A PERDETERMINED SPEED TWO OF THE STORED LINES SIMULTANEOUSLY, MEANS FOR DETECTING AN ABRUPT CHANGE OF SIGNAL LEVEL READ OUT FROM EITHER ONE OF SAID LINES, MEANS RESPONSIVE THERETO FOR HALTING THE SCAN OF THAT LINE AND ACCELERATING THE SCAN OF THE OTHER LINE, MEANS FOR DETECTING AN ABRUPT CHANGE OF SIGNAL LEVEL READ OUT FROM SAID OTHER LINE, MEANS RESPONSIVE THERETO FOR HALTING THE SCAN OF SAID OTHER LINE AND RESUMING AT ACCELERATERD RATE THE SCAN OF THE SAID ONE LINE UP TO THE POINT WHERE SAID SCANS COINCIDE AND THEREUPON RESTORING BOTH SCANNING SPEEDS TO SAID PREDETERMINED SPEED, MEANS FOR GENERATING AN INTERPOLATED SIGNAL RELATED TO A SCANNING SPEED INTERMEDAITE THE SCANNING SPEEDS AT WHICH THE SAID TWO LINES ARE BEING READ AND AT A SIGNAL LEVEL INTERMEDIATE THE SIGNALS READ OUT FROM SAID TWO LINES WHILE BOTH ARE SCANNING, SAID MEANS BEING RESPONSIVE TO OPERATION OF SAID FIRST NAMED DETECTING MEANS TO EQUATE THE INTERPOLATED SIGNAL TO THAT OF THE LINE STILL SCANNING WHEREBY AN ABRUPT CHANGE EQUIVALENT TO THAT EXPERIENCED IN THE TWO STORED LINES WILL BE GENERATED IN THE INTERPOLATED LINE SIGNAL AT A POINT IN ITS SCAN INTERMEDIATE THOSE EXPERIENCED IN THE SAID STORED LINES, AND MEANS FOR ASSEMBLIMG AN INTERLACED VERSION OF THE RECEIVED SIGNALS AND THE INTERPOLATED SIGNALS TO PROVIDE A PICTURE PRESENTATION.