alt.sci.physics.acoustics

Chronic Philharmonic wrote:

> "Richard Crowley" wrote in message
> The only way I know of to get new frequencies is to use some non-linear
> device (e.g., modulator). I gave one example, and you only need one waveform
> to do it.

Correct. And note that for four sine waves, each of only one frequency,
each being shifted 90 degrees, will give four zero-crossings per one kHz
cycle. Therefore, when using a multiplication algorithm, for zero
crossings per cycle can result in a 4 kHz signal. Multiplication between
zero-crossings will give small loops, of alternating plus and minus
values, of amplitude diminished (I figured 1/4, someone else figured
1/8). No matter, a 4 kHz wave results.

Another DSP algorithm is to use two squaring circuits in succession. In
that case, as noted by others, a net DC value will result. But no
matter, the 4 kHz is still produced which is what everyone wants...

Angelo Campanella