Analog delay line

An analog delay line is a network of electrical components connected in cascade[dubious – discuss], where each individual element creates a time difference between its input and output.

In 1941, Gerald Tawney of Sperry Gyroscope Company filed for a patent on a compact packaging of an inductor–capacitor ladder network that he explicitly referred to as a time delay line.

In 1938, William Spencer Percival of Electrical & Musical Industries (later EMI) applied for a patent on an acoustical delay line using piezoelectric transducers and a liquid medium.

The problem of suppressing multipath interference in television reception motivated Clarence Hansell of RCA to use delay lines in his 1939 patent application.

[8] Other GE employees, John Rubel and Roy Troell, concluded that the insulated wire could be wound around a conducting core to achieve the same effect.

[12][13] Arlenberg developed the idea of complex 2- and 3-dimensional folding of the acoustic path in the solid medium in order to package long delays into a compact crystal.

[14] The delay lines used to decode PAL television signals follow the outline of this patent, using quartz glass as a medium instead of a single crystal.

Electric delay line ( 450 ns ) from a color TV-set. Made of enamelled copper wire, wound in one layer around a copper tube and forming a distributed inductor-capacitor network .
A magnetostrictive torsion wire delay line
Schematic of circuit connections to the acoustic delay line used in NBS mercury memory (top); block diagram of the mercury memory system (bottom)
FUJIC 's ultrasonic mercury delay line memory (capacity: 255 words = 8,415 bits )
Ultrasonic delay line from a PAL color TV (delay time 64 μs ), showing path of sound waves (pink) and transducers (yellow, upper left)