Milovana.com

That's a nice example. If we add a 30hz signal, then the amp will filter out that signal and the result will be unpredictable (mine has a hardware filter below ~110hz). But I see your point.

I did some more digging... For combinations of two carrier frequencies, wikipedia has the sum to product formulas.

Edit: the title of this charts says "carrier modulation". That's wrong, should be "multiple carrier frequency"


These are clearly identical. Conclusion: any combination of two carrier frequencies can be expressed as amplitude modulation.

With some pen and paper, I was able to work out...


sin(444) + sin(555) + sin(666) + sin(777) = sin(610.5) * cos(111) * cos(55.5) * 4

I'm not sure if this works for every combination of carrier frequencies, but it works for this one. In conclusion, multiple carrier frequency and amplitude modulation are the same thing.

Personally I think the amplitude modulation numbers are nicer, so that's what I will use...

diglet wrote: Tue Jan 31, 2023 11:27 pm That's a nice example. If we add a 30hz signal, then the amp will filter out that signal and the result will be unpredictable

Actually it won't be unpredictable - you will get the rest of the signal (like you added that inverse 30Hz), which will be quieter of course as 30Hz is large part of energy that this signal carries.

diglet wrote: Tue Jan 31, 2023 3:36 pm The sensation between figure 2 and 3 should be almost identical. Method 3 is much easier to implement, is there any convincing reason to prefer the method of figure 2?

You wrote about amplitude modulation by adding signals. This is theoretical possible because if you add two sine signals, one with frequency f_1 and another one with frequency f_2, you get:

sin(2*pi*f_1*t) + sin(2*pi*f_2*t) = 2 * sin(2*pi*(f_1+f_2)/2*t) * cos(2*pi*(f_1-f_2)/2*t),

i.e. adding these signals is equivalent to multiplying a sine signal with the frequency (f_1+f_2)/2 with a cosine signal with the frequency (f_1-f_2)/2 .

For more than two signals the situation becomes complicated. But in any case, if you add multiple signals with the frequencies f_i the rate f at which the resulting signal repeats, is the largest f, that satisfies f*m_i=f_i where m_i are integers. E.g. if you add a 444 Hz signal, a 555 Hz signal, a 666 Hz signal and a 777 Hz signal the result is repeated 111 times (not 110) per second. There is no reason to do that with that frequency combination (see below).

On the other hand, if you add 1000 Hz signal and a 1001 Hz signal, that signal is repeated once per second. You achieve (almost) the same by multiplying a 1000 Hz signal with a 1 Hz signal with the waveform |sin(pi*1Hz*t)|

So you can modulate the amplitude by adding signals, but that is stupid because it is unhandy and unpredictable if you use more than two signals. Instead of this you should do it like everyone (I know) does it: by multiplying.

diglet wrote: Tue Jan 31, 2023 3:36 pm Is there a theoretical reason why the square modulation in figure 4 would feel better or worse at high frequencies (~50-100hz), what about low frequencies (1~5hz)?
When using lower modulation frequencies, should we increase both the off and on time, or does it make sense to keep the on time constant and only increase the off time?

Regarding frequencies: As mentioned, neurons can only be fired at a certain maximum rate which is about 50 Hz at sensitive places and less at less sensitive places. But in order to be triggered they need a certain voltage level for a certain time. Thus, instead of using a continuous sinusoidal signal you can also fire pulses at a rate higher than 100 Hz (important: with alternating polarity in order to avoid DC currents) and a pulse width of about 0.5ms to 1ms. Battery powered devices work like this. But then phase modulation becomes non-trivial (multi-phase signals). The strange signal in your last plot would feel similar to signal that fires a positive and a negative pulse every 1/111 s. That is why I consider it as unpredictable.

If you modulate a 1000 Hz carrier signal with a 100 Hz rectangular signal that will feel almost same as a modulated 1000 Hz signal. (Not exactly the same because for statistic reasons some neurons are not fired at maximum rate.)

But if you modulate with low frequency signals there is another effect: inhibition. As soon a neuron is triggered the voltage threshold at which the neuron is triggered again is increased. This offset decreases over time, roughly to zero after 250ms. I.e. if you modulate with a 1 Hz rectangular waveform all neurons are fired at the same time at the rising edge. Whether this is good or bad depends on what you deserve.

Or in other words, at low modulation frequencies the off time and the rise time matters.

Thanks, that was really helpful. I found this paper with a few diagrams indicating what happens at the frequencies above the maximum firing speed, might be useful for anyone else following the discussion. See figure 3 https://www.frontiersin.org/articles/10 ... 00783/full. Not tested in this paper, but they state in the discussion that increasing the stimulation rate eventually results in a decreases in firing rate.

I was looking at some old diagrams from stimaddict, those suggest that a large part of the current flows through the dorsal nerve. Are there any tricks we can do (waveform wise) to focus the stimulation on the neurons near the surface?

I might perform some experiments with single-pulse stimulation later.

Someone should update cfs6t08p's funscript converter to work with carrier frequency + modulation, instead of multiple carrier frequency.

diglet wrote: Sat Feb 04, 2023 2:54 pm
Someone should update cfs6t08p's funscript converter to work with carrier frequency + modulation, instead of multiple carrier frequency.

What do you mean? If you type in just one frequency, that is what it does - left channel is fixed frequency, and right one is modulated back and forth as per funscript. We can't update their converter, but I have forked version where I can make changes.

EDIT: or do you mean have one frequency + modulation of that frequency for left channel and then modulate that for other channel? Would that be fixed frequency modulation or use 2 axes from funscript?

Like mantrid says, you can do amplitude modulation by combining multiple carrier frequencies. That is what the default settings (420,520,620) do. But that's stupid because it's confusing and doesn't do anything that can't be done with carrier frequency multiplied by a modulation signal.

Here is the UI I made for my tool, for reference:



It's a lot more obvious what it actually does. Strictly speaking it doesn't add functionality, it just makes it easier to understand, no longer relying on the user to input frequencies that have some common multiple.

diglet wrote: Sat Feb 04, 2023 2:54 pm I was looking at some old diagrams from stimaddict, those suggest that a large part of the current flows through the dorsal nerve.

You may have this in mind.

diglet wrote: Sat Feb 04, 2023 2:54 pmAre there any tricks we can do (waveform wise) to focus the stimulation on the neurons near the surface?

You can try to reduce the pulse width / increase the carrier frequency. That shifts the balance to the more sensitive nerves at the surface. But that is not what we want, multiphase estim lives from the magic internal variations.

Release notes for v1.10 and V1.11

This is most likely the last version of the sound library, because MPGenerator and GServer are discontinued due to lack of acceptance of the approach. Sound generation has been moved to gasm which became an independent project (formerly it was a part of the MPGenerator package)

See the initial post for a general description and the download link.

Changes:

• There are two variants of the library. v1.10 is the rough one and V1.11 it less rough. Within the tease you can switch by pressing "Repeat 1.10" or the "Repeat 1.11". Pain files are equal.
• A few new sound files and sessions added (mixed pleasure+pain)
• Carrier frequency of the pre-build files was reduced form 1000 Hz to 600 Hz
• The package contains two entry files: 'EStimSurprise.html' and 'EStimSurprise-GServer.html'. The last one is the older one and still supports GServer, see the topic "Playback using gserver" in the initial post