Interpolator for observation of curve on TV screen - uses two comparators, line sweep counter, shift register, image memory and XOR-gate

摘要

A counter (1) sums the line synchronising pulses (3) and is set to zero by a frame synchronising pulse (2). A second counter (4) sums the points along the axes given by a clock signal (6) and is set to zero by a line sync pulse (5). This counter output is stored in a memory (11) and a comparator (7) analyses the two counter outputs. When they are equal, the comparator outputs a pulse (13) to illuminate the spot. A monostable (14) excludes pulses between the successive samples. A second comparator (16) utilises a preceding sample value via a register (19) to provide vertical interpolation via exclusive OR gate (22). A monostable (24) inhibit circuit pulses between samples. A switch (25) and ring counter (26) enable the area to be observed in an envelope generated by the curve.