AM electromagnetic waves: 20 KHz modulation frequency on an astronomically-low carrier frequency
On Jul 3, 12:50 pm, John Fields wrote:
On Mon, 2 Jul 2007 23:03:36 -0700, "Ron Baker, Pluralitas!"
wrote:
"John Smith I" wrote in message
...
Radium wrote:
snip
Suppose you have a 1 MHz sine wave whose amplitude
is multiplied by a 0.1 MHz sine wave.
What would it look like on an oscilloscope?
snip
What would it look like on a spectrum analyzer?
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--------+--------------------+-------+------+----
100kHz 0.9MHz 1MHz 1.1MHz
Then suppose you have a 1.1 MHz sine wave added
to a 0.9 MHz sine wave.
What would that look like on an oscilloscope?
snip
Tricky!!!
It looks like AM but it isn't, it's just the phases sliding past
each other slowly and algebraically adding which creates the
illusion.
What would that look like on a spectrum analyzer?
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-----------------------------+--------------+----
0.9MHz 1.1MHz
--
JF
But if you remove the half volt bias you put on the
100 kHz signal in the multiplier version, the results
look exactly like the summed version, so I suggest
that results are the same when a 4 quadrant multiplier
is used.
And since the original request was for a "1 MHz sine
wave whose amplitude is multiplied by a 0.1 MHz sine
wave" I think a 4 quadrant multiplier is in order.
....Keith
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