[sdiy] wireless patching

[Quincas Moreira]

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> 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 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> 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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