Re: [LTSPICE] mixer needed


"Helmut Sennewald" <helmutsennewald@xxxxxxxxxxx> wrote in message
news:d91kc4$h2p$03$1@xxxxxxxxxxxxxxxxxxxx
> "colin" <no.spam.for.me@xxxxxxxxxxxx> schrieb im Newsbeitrag
> news:sUXse.23584$m4.2633@xxxxxxxxxxxxxxxxxxxxxxx
> >
> > "Helmut Sennewald" <helmutsennewald@xxxxxxxxxxx> wrote in message
> > news:d91fki$1pa$00$1@xxxxxxxxxxxxxxxxxxxx
> >> "colin" <no.spam.for.me@xxxxxxxxxxxx> schrieb im Newsbeitrag
> >> news:i4Xse.23556$m4.16585@xxxxxxxxxxxxxxxxxxxxxxx
> >> > "colin" <no.spam.for.me@xxxxxxxxxxxx> wrote in message
> >> > news:XxTse.22599$m4.9316@xxxxxxxxxxxxxxxxxxxxxxx
> >> >> Hi,
> >> >> is there a mixer availble in LTSPICE?
> >> >>
> >> >> just a simple idealised (double balanced) one would do ..
> >> >>
> >> >> ive used the modulator before but this can only modulate a fixed
> >> >> singal
> >> >> frequency
> >> >> i need to mix 2 multi frequency signals.
> >> >>
> >> >
> >> > ok my next problem is i need to introduce a sinusoidaly varying time
> > delay
> >> > into a signal, i cant think what i can use to do this, in the real
> >> > world
> >> > it
> >> > is the result of varying transmision distance wich is what i wish to
> >> > examine
> >> > the effects of .. any ideas ? i cant use the sffm as it is not a
single
> >> > frequency.
> >> >
> >> > Colin =^.^=
> >>
> >> Hello Colin,
> >>
> >> No problem. The B-source can do it. The variable "time" is available
> >> in the behavioral sources(B).
> >>
> >> V=sin(2*pi*f0*(time+deltaTime*sin(2*pi*fdelta*time)))
> >>
> >> With numbers:
> >>
> >> V=sin(2*pi*1k*(time+0.1m*sin(2*pi*10*time)))
> >>
> >> This is a 1kHz sine waveform with a varying delay of +/- 0.1ms and
> >> a frequency of 10Hz.
> >>
> >> Increase your time window for the FFT to multiples of 0.1 seconds
> >> in this case. You should also rise the number of samples in
> >> the FFT to 131072. The spectrum looks like PM.
> >>
> >> Best regards,
> >> Helmut
> >
> > Hi Helmut,
> > thanks again, this would be fine if my signal was a single frequency,
> > but then i cld use the sffm FM modulator, but unfortunatly i cant reduce
> > it
> > to a sinewave,
> > i need something that effectivly adds PM to an existing voltage node
> > within
> > the simulator and i cant see any functions in b-Source that i could do
> > that
> > with.
> >
> > maybe i need to do something like make a model for a transmision line
and
> > vary the length ?
> >
> > I gues as a last resort I could make a lumped transmision line with
> > varactors etc.
> >
> > Colin =^.^=
>
> Hello Colin,
>
> Sorry for misunderstanding your desire.
>
> There is a delay function in LTspice, but it's only ok to
> use it with a constant delay. This means you could only
> change the delay in a stepped simulation(.step).
> It is not intended for varying delays.
>
>
> V=delay(V(x1), 0.1m)
>
> or
>
> .step param DELAY1 0 0.1m 0.02m
> V=delay(V(x1),{DELAY1})
>
> Best regards,
> Helmut
>

Hi,
thanks again, this is interesting as there is no mention of the delay
function in the help section, it pays to ask :)

I tried to put a variable in the delay, it would not accept the sine
function eg V=delay(v(a),sine(time)) but it would accept
V=delay(v(a),0.001+time/1000) wich gives the result expected it also
accepted a voltage as the second term eg V=delay(v(a),v(b)) wich is
interesting as i can use a sine voltage, however it does give rather jumpy
results but i expect i can improve this with tstep etc.

I gues i could also add sinousoudaly varying amounts of the delayed and non
delayed voltage.

Colin =^.^=


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