[sdiy] Ring Mod (was Re: Hadamard Transform Network)

[Mike HEQX]

There is a form of "AM" radio which is the version where the frequency 
of the carrier produces side bands that are sums and differences with 
relation to the carrier and the amplitude of the carrier is only related 
to the relative amplitudes of the side bands. Is this what we are 
talking about?

Sometimes the definition of AM and FM get confused when talking about 
radio at least.

Mike


On 5/16/2017 12:13 PM, Donald Tillman wrote:
>> On May 16, 2017, at 8:40 AM, Tim Ressel <timr at circuitabbey.com> wrote:
>>
>> But you bring up an interesting point: 4QMs multiply, but they produce x+y, x-y tones. Anyone got the math on that?
> High school trigonometry.
>
> Trig identity:
>     cos(a+b) = cos(a)cos(b) - sin(a)sin(b)
>
> Another trig identity, derivable from the first:
>     cos(a-b) = cos(a)cos(b) + sin(a)sin(b)
>
> Add'm:
>     cos(a+b) + cos(a-b) = 2 cos(a)cos(b)
>
> Your multiplication operation is on the right, your sum and difference tones are on the left.
>
>    -- Don
>
> --
> Don Tillman
> Palo Alto, California
> don at till.com
> http://www.till.com
>
>
>
>
>
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