On 6/19/2012 8:37 AM, Michael J. Mahon wrote:
This was a common technique in
radar scopes. (And there it's not even being used as a frequency
multiplier.)
A bit off-topic but IMHO an interesting piece of trivia.
By the end of the 20th century there was a PLL in every house. Every house
that had an NTSC (or PAL) TV to regenerate the color sub-carrier
from just 9 cycles of the "color burst" after line sync. However in the early
days of NTSC they used a very high Q "LC tank" equivalent - a quartz crystal
that was excited during the color burst by those 9 periods and kept in sync
till the next line. Not quite perfect. Probably one of the reasons NTSC is
claimed by some to stand for Never Twice [the] Same Color. :)