[sdiy] wireless patching

[Quincas Moreira]

Well, the RC controlers use potentiometers right? I´m assuming there's
already a circuit converting the joystick-attenuated voltages into pwm...

On Fri, May 26, 2017 at 2:31 AM, <rsdio at audiobanshee.com> wrote:

> My point is that the original question did not assume PWM already existed,
> or even digital.
>
> The original question concerned wireless modular linking of analog CV.
> Quincas asked whether a uP and ADC were necessary, or if there was a simple
> analog way to do it. I don't know of a simple way to create a PWM signal
> from an analog voltage (although I'm not assuming it doesn't exist just
> because I don't know about it :-)
>
> It could be more trouble to create PWM so that you can use RC, rather than
> simply use FM via some other method.
>
> The latency that you complain about in a digital word protocol would not
> necessarily be worse than the 50 Hz update rate of the RC solution. That's
> a 20 millisecond latency right there for the RC method. In that length of
> time, a 100 kbps digital protocol could transfer 2,000 bits, which is more
> than enough bandwidth for 8 channels of 16-bit words. I'm thinking that a
> digital protocol would actually be lower latency than RC updates.
>
> Another issue is that the RC solution is limited to a 50 Hz sample rate,
> whereas the digital word protocol could manage a higher sample rate - maybe
> even 16 times the sample rate. Fortunately, the RC solution does seem to
> sample all channels at 50 Hz, but that's a fairly low limit.
>
> Brian
>
>
> On May 25, 2017, at 11:43 PM, Roman Sowa <modular at go2.pl> wrote:
> > PWM is digital output, so what's your point?
> > Using digital words over this radio module would require much higher
> bandwidth, they usually are limited to 100kbps, sometimes much less. Higher
> bandwidth models don't have keying input but take SPI or I2C, packetize it
> and send embeded in some protocol, sometimes with 2-way link. That creates
> latency.
> >
> > As Matthias just said, this is what RC control uses, TDM-ed multiple PW.
> This is the best solution I think. One visit in RC store and your wireless
> connectivity project finished, just add filters to servo outputs of the
> receiver, as their output is PWM.
> >
> > Roman
> >
> > W dniu 2017-05-25 o 22:52, rsdio at audiobanshee.com pisze:
> >> FSK and ASK both assume digital input. If you want to send analog
> >> data, then you should be able to use standard FM, which can transmit
> >> analog signals. So long as the pilot frequency and the signal
> >> frequency survive the transmission, you should be able to reconstruct
> >> the analog signal on the receiving end.
> >>
> >> I do think that multiple CV would require multiple transmit
> >> frequencies and multiple receivers, though, to keep the signals
> >> distinct. That would be true with ASK/FSK or straight FM.
> >>
> >> Brian Willoughby Sound Consulting
> >>
> >>
> >> On May 25, 2017, at 2:29 AM, Roman Sowa <modular at go2.pl> wrote:
> >>> BT is no good for realtime. How about really simple $2 RF modules
> >>> that have FSK or ASK input? Not sure if you can freely modulate
> >>> with any PWM signal or is it quantized to some fixed data rate, but
> >>> common sense tells me that the simples cheapest module just drive
> >>> the radio directly. So you have wireless PWM link, and that's just
> >>> one step from CV.
> >>>
> >>> Roman
> >>>
> >>> W dniu 2017-05-25 o 01:13, Quincas Moreira pisze:
> >>>> Hey friends! If you were to design a fast and precise wireless
> >>>> transmission and reception system for eurorack, how would you doi
> >>>> it? Synth 1 > ADC > uP
> >>>>> Bluetooth > uP > DAC > synth 2 ?  Or is there a simple analog
> >>>>> way to
> >>>> do it with RF?
> >>>>
> >>>> I mainly want to send control signals, but as we know, those can
> >>>> be up in the audio frequencies or higher!
> >>>>
> >>>> The idea is to have like, 4 systems set up on 4 corners of a room
> >>>> and inter-patch them without stretching long cables all over the
> >>>> place. I think 8 sends and 8 receives on each remote patch box
> >>>> would suffice, and some system to match sends to receives.
>
>
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-- 
Quincas Moreira
Test Pilot at VBrazil Modular
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