Newnes Audio and Hi-Fi Engineer's Pocket Book, 3rd Edition

143

but a shallow penetration into the 5 pm thick tape coating, so it

erases only that part of the sound track near the surface. The

deeper portions remain, resulting in a depth multiplex

recording, having two layers.

To separate sound and vision signals on replay, the azimuth

settings of the heads are displaced by 30

.

The h.f. response of

each head to signals of the opposite azimuth is well below the

respective carrier frequencies, so there is a high rejection of the

opposite signal. This is necessary in spite of the separation

afforded by the sound and vision tuned circuits, because there

is considerable overlapping of sidebands.

:

Tape