Pseudo-random electron beam scanning system for narrow bandwidth image transmission

Claim 1

IN AN ELECTRON BEAM SCANNING SYSTEM OF SUCCESSIVE FIELDS COMPRISING SUBSTANTIALLY EQUALLY SPACED LINES OF SUBSTANTIALLY EQUALLY SPACED DOTS, AT A SPACING BETWEEN ADJACENT LINES OF SUBSTANTIALLY 2M DEFLECTION UNITS AND AT A SPACING BETWEEN ADJACENT DOTS ON THE LINES OF SUBSTANTIALLY 2N DEFLECTION UNITS (M AND N BEING INTEGERS), APPARATUS FOR DEFLECTING SUCCESSIVE FIELDS SUCH THAT 2M+N SUCCESSIVE FIELDS TOGETHER PROVIDE A DOT IN EACH UNIT DEFLECTION AREA BETWEEN THE DOTS IN A GIVEN FIELD BY PROVIDING PERIODIC DEFLECTIONS ADDITIVELY IN THE DIRECTION OF SAID LINES AND IN A DIRECTION SUBSTANTIALLY PERPENDICULAR THERETO, COMPRISING RESPECTIVE MEANS FOR PROVIDING AT LEAST ONE DEFLECTION OF EACH OF THE AMPLITUDES 1,2,4,... 2M-1 DEFLECTION UNITS IN THE DIRECTION SUBSTANTIALLY PERPENDICULAR TO THE LINES, AND RESPECTIVE MEANS FOR PROVIDING AT LEAST ONE DEFLECTION OF EACH OF THE AMPLITUDES 1,2,4,..2N-1 DEFLECTION UNITS IN THE DIRECTION OF THE LINES, AT RESPECTIVE HARMONICALLY RELATED FREQUENCIES SUCH THAT THE COMBINED DEFLECTIONS COMPRISE AT LEAST ONE DEFLECTION OF EACH SUCCESSIVE FIELD, OF EVERY SECOND FIELD, OF EVERY FOURTH FIELD, ... OF EVERY 2M+N-1TH FIELD.