Attachments :
Sorry, found this in the archives but it doesn't seem to completely answer my question. It helps, though!
Bob Hearn wrote:
6. You can make a Random Voltage Generator even without a Noise Source!
John described how to turn the SSG into an RVG, with smooth, stepped,
and pulse random voltage outputs. This is also described in the Gold
book (page 5-39). This is an incredibly cool patch - if you fully
understand it, you have got the SSG down. However, one thing is that
that patch requires the S/H source from a Noise Source module (or a
Random Source, which includes a Noise Source internally). That signal
is a randomly modulated sawtooth wave. The idea is that every time you
sample it (unless two sequential times are very close together), you
get a random voltage. (Actually the Gold book mistakenly says to use
the S/H output, not S/H source - that will not work.) Well, it turns
out you can make an RVG even without a Noise Source! Just use a regular
sawtooth wave instead of the S/H source, say from a PCO. (A DSG would
also work.) Set the PCO to high range, with the frequency knob at 12
'clock. Now, this signal is not randomly modulated, so you might think
it would not work - you won't get a random voltage when you sample it.
But in fact, the overall system is chaotic; the samples you get are
actually random, because they are sampled at random intervals - because
the patch in fact works! It's circular - the samples are random,
because the patch output voltages are random, because the samples are
random... but it works. I haven't done the hairy math to ensure that
the system will never get locked into a repeating state, but the output
looks the same to me as an actual RVG. In dynamical terms, I believe
the cyclic states are unstable.
Note that if the sawtooth PCO rate is much faster than 12 o'clock, the
patch doesn't work - I think because the signal is changing too fast
for the Stepped section to lock onto. This makes sense given #1 above;
the Stepped module is actually slewing for a brief period, and not
actually sampling. Setting the PCO rate to 12 o'clock roughly matches
the S/H source signal's mean frequency, btw. Of course, this is really
only useful if you happen to have an SSG but no Noise Source... still,
I think it's cool that you can get your randomness for free, as it
were.
-------------- Original message ----------------------
From: mrcarp@...
Bob Hearn wrote:
6. You can make a Random Voltage Generator even without a Noise Source!
John described how to turn the SSG into an RVG, with smooth, stepped,
and pulse random voltage outputs. This is also described in the Gold
book (page 5-39). This is an incredibly cool patch - if you fully
understand it, you have got the SSG down. However, one thing is that
that patch requires the S/H source from a Noise Source module (or a
Random Source, which includes a Noise Source internally). That signal
is a randomly modulated sawtooth wave. The idea is that every time you
sample it (unless two sequential times are very close together), you
get a random voltage. (Actually the Gold book mistakenly says to use
the S/H output, not S/H source - that will not work.) Well, it turns
out you can make an RVG even without a Noise Source! Just use a regular
sawtooth wave instead of the S/H source, say from a PCO. (A DSG would
also work.) Set the PCO to high range, with the frequency knob at 12
'clock. Now, this signal is not randomly modulated, so you might think
it would not work - you won't get a random voltage when you sample it.
But in fact, the overall system is chaotic; the samples you get are
actually random, because they are sampled at random intervals - because
the patch in fact works! It's circular - the samples are random,
because the patch output voltages are random, because the samples are
random... but it works. I haven't done the hairy math to ensure that
the system will never get locked into a repeating state, but the output
looks the same to me as an actual RVG. In dynamical terms, I believe
the cyclic states are unstable.
Note that if the sawtooth PCO rate is much faster than 12 o'clock, the
patch doesn't work - I think because the signal is changing too fast
for the Stepped section to lock onto. This makes sense given #1 above;
the Stepped module is actually slewing for a brief period, and not
actually sampling. Setting the PCO rate to 12 o'clock roughly matches
the S/H source signal's mean frequency, btw. Of course, this is really
only useful if you happen to have an SSG but no Noise Source... still,
I think it's cool that you can get your randomness for free, as it
were.
-------------- Original message ----------------------
From: mrcarp@...
> Furthermore, what is the 'randomly modulated sawtooth wave' at the S/H Output of
> the Noise Source?
> Can I use any random source to achieve the results on p. 5-39?
> Can I use Pink Noise for the 1/F patch?
>
> -------------- Original message ----------------------
> From: "simulacreant" <mrcarp@...>
> > How do I patch the 1/F function per p. 5-38 of the Gold Book without a
> > S/H Source on a NOISE module? What is the S/H Source, anyway? I see it
> > on the RS module.
> > Can I do this on my Animal panel, alone?
> > Thanks!
> >
> >
>
>