2007-05-10 04:30:09 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Engineering
The envelope of the AM signal must never go through zero, or severe distortion would result.
Because the AM signal is produced simply by multiplying the carrier by the message signal, the message signal has to have enough DC added to make its negative values positive, so that the resulting signal never goes through zero.
2007-05-10 04:44:08 · answer #1 · answered by rrabbit 4 · 0⤊ 0⤋
I agree with Gene. An AM modulator requires no DC shift.
Unless if you have a DSB generator, and are trying to unbalance the mixer to create a carrier, then modulate it? That would give you AM.
Kind of the long way around though.
2007-05-10 22:31:20 · answer #2 · answered by charley128 5 · 0⤊ 0⤋
I agree with "rrabbit". In double sideband modulation, a DC bias is applied to avoid the message signal going below zero.
More reading on
http://www.mee.tcd.ie/~ledoyle/TEACHING/3C5/dsb-ssb-vsb-qam-handout.pdf
2007-05-10 13:52:26 · answer #3 · answered by Marianna 6 · 0⤊ 0⤋
You don't. I'm not sure where you got that idea from. Worked in RF for 30 years and never did that.
2007-05-10 11:36:05 · answer #4 · answered by Gene 7 · 0⤊ 0⤋