[sdiy] wireless patching
Roman Sowa
modular at go2.pl
Fri May 26 10:38:18 CEST 2017
We all know you will start building it before I got the chance to reply
"try it...".
Higher rate means more noise and poor linearity, but where's the fun if
everything was clean. By the way this circuit should have terribly bad
linearity anyway.
Roman
W dniu 2017-05-26 o 10:06, Quincas Moreira pisze:
> http://213.114.137.49/use/rc_enc_02.htm
>
> this looks interesting... 6 channels
>
> could the rate be hacked to go higher ?
>
> On Fri, May 26, 2017 at 2:57 AM, Roman Sowa <modular at go2.pl
> <mailto:modular at go2.pl>> wrote:
>
> Creating PWM from CV is pretty easy, I haven't thought it requires
> explaining. Simply sawtooth oscillator and comparator.
>
> But you're right about the latency in RC world, I was typing faster
> than thinking. RC devices have low update rate considering modular
> use. After a quick check I see the fastest models have 11ms latency,
> and they are all pure digital anyway.
>
> Roman
>
>
> W dniu 2017-05-26 o 09:31, rsdio at audiobanshee.com
> <mailto:rsdio at audiobanshee.com> pisze:
>
> 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
> <mailto: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
> <mailto: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
> <mailto: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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