AM electromagnetic waves: 20 KHz modulationfrequencyonanastronomically-low carrier frequency
On 7/7/07 9:17 PM, in article , "Ron
Baker, Pluralitas!" wrote:
"Don Bowey" wrote in message
...
On 7/4/07 8:42 PM, in article ,
"Ron
Baker, Pluralitas!" wrote:
"Don Bowey" wrote in message
...
On 7/4/07 10:16 AM, in article ,
"Ron Baker, Pluralitas!" wrote:
"Don Bowey" wrote in message
...
On 7/4/07 7:52 AM, in article
,
"Ron
Baker, Pluralitas!" wrote:
snip
cos(a) * cos(b) = 0.5 * (cos[a+b] + cos[a-b])
Basically: multiplying two sine waves is
the same as adding the (half amplitude)
sum and difference frequencies.
No, they aren't the same at all, they only appear to be the same
before
they are examined. The two sidebands will not have the correct phase
relationship.
What do you mean? What is the "correct"
relationship?
One could, temporarily, mistake the added combination for a full
carrier
with independent sidebands, however.
(For sines it is
sin(a) * sin(b) = 0.5 * (cos[a-b]-cos[a+b])
= 0.5 * (sin[a-b+90degrees] - sin[a+b+90degrees])
= 0.5 * (sin[a-b+90degrees] + sin[a+b-90degrees])
)
--
rb
When AM is correctly accomplished (a single voiceband signal is
modulated
The questions I posed were not about AM. The
subject could have been viewed as DSB but that
wasn't the specific intent either.
You should take some time to more carefully frame your questions.
Do you understand that a DSB signal *is* AM?
So all the AM broadcasters are wasting money by
generating a carrier?
You are an ignorant, useless troll, and not worth my time
Post your intention; it might help.
onto a carrier via a non-linear process), at an envelope detector the
two
sidebands will be additive. But if you independe ntly place a carrier
at
frequency ( c ), another carrier at ( c-1 khz) and another carrier at
(c+
1
kHz), the composite can look like an AM signal, but it is not, and only
by
the most extreme luck will the sidebands be additive at the detector.
They
would probably cycle between additive and subtractive since they have no
real relationship and were not the result of amplitude modulation.
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