From: "Bevan Weiss"
References: <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org>
Subject: Re: How does a mixer work?
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X-Original-Trace: 26 Oct 2002 18:58:02 +1300, news.orcon.net.nz
Date: Sat, 26 Oct 2002 18:58:04 +1300
NNTP-Posting-Date: Sat, 26 Oct 2002 18:58:03 NZDT
What the HELL is wrong with you people???
A mixer works by taking two input signals and creating (perfectly) two
output signals. It does this by multiplying the instantaneous voltages
(/current etc, depending on configuration) of the two input signals together
to create the sum and difference frequencies. As per mathematical
sin(x)*sin(y) == 1/2( cos(x+y) - cos(x-y) )
There is no argument with this...
There can be NONE, this is a mathematical identity, anybody that knows
anything about maths knows that this has been proved to the nth degree, much
like 1+1 = 2.
Any other outputs, ie harmonics etc, are simply side effects of the
non-ideal mixing process. ie the most common form being a simple output
signal gating, which simply takes the sign of one input signal and uses that
to change the sign of the output signal, ie
output = input2*sign(input1);
This effectively gives an output which consists of the sum, the difference
and the sum and differences between input2 and all the harmonics present in
the squared input1.
Any other errors introduced, are caused by the circuitry, ie amplifiers that
are not completely linear, semiconductor junctions which have shot noise,
flicker noise and thermal noise, and everything else surrounding the system
which may have the same, as well as inductively/capacitively induced
I'm not seeing what the big argument is all about.
When you add sine waves, you do indeed just add sine waves..
ie sin(x) + sin(x) = 2sin(x);
however when you multiply sine waves, as in mixing (non-audio signals)
sin(x) * sin(x) = 1/2(cos(2x) - cos(0))
= 1/2(cos(2x) - 1)
"Richard Steven Walz" wrote in message
> In article ,
> Don Pearce wrote:
> >On 23 Oct 2002 21:46:06 GMT, email@example.com (Richard
> >Steven Walz) wrote:
> >>In article ,
> >>Don Pearce wrote:
> >>>On 21 Oct 2002 06:55:46 GMT, firstname.lastname@example.org (Richard
> >>>Steven Walz) wrote:
> >>>>>>You're in the wrong crowd for your pretense, you piece of shit.
> >>>>>>We all know what I meant, AND that you're a disingenuous asshole!
> >>>>>So come on - just tell us what you meant. Did you mean:
> >>>>>"When you add sine waves you wind up effectively adding them"?
> >>>>>That would be correct, but hardly illuminating.
> >>>>NO, you STUPID PIECE OF SHIT!!
> >>>>sin(x)*sin(y) = (1/2)cos(x+y) - (1/2)cos(x-y)
> >>>>What in the fuck is WRONG with you!??
> >>>Now I understand! You think that because sin(x)*sin(y) can be
> >>>expressed in cos terms of (x+y) then multiplying the sinusoids on the
> >>>left is effectively the same as adding the coses (which we accept as
> >>>sinusoids) on the right!
> >>No, that's what YOU think I think. You didn't even quote me properly
> >>or else you'd know better, now just go away like a good little piece
> >>of shit waste of time.
> >OK, now you've really got me puzzled. The only pair of trig identities
> >I can see summed (OK, it is a minus, but who's counting?) are those
> >coses - which I am also happy to consider sinusoids for the purposes
> >of the game - could I be more reasonable?
> >And now you say it isn't those at all. I give up.
> Sin or Cos doesn't even matter, you shit, that's just a matter of phase
> and initial conditions! How can you even STAND to KNOW that you're such
> a piece of shit!??? All you're doing is playing STUPID!
> -Steve Walz email@example.com ftp://ftp.armory.com/pub/user/rstevew
> Electronics Site!! 1000's of Files and Dirs!! With Schematics Galore!!
> http://www.armory.com/~rstevew or http://www.armory.com/~rstevew/Public