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POHow to transmit binary through a single waveform
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8763319
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2012-01-06T19:27:26.940
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2012-06-14T03:38:07.407
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2012-01-06T23:46:02.030
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text
Body
The project I'm working on poses a curious technical challenge. A digital device needs to transmit data to the iPhone via the microphone jack socket. I need to code an interface from both the microcontroller and from the iPhone end. Is there any established protocol for this particular problem? I don't have the luxury of twin clock and data line (ala PS/2 protocol <a href="https://en.wikipedia.org/wiki/PS/2_connector" rel="nofollow">https://en.wikipedia.org/wiki/PS/2_connector</a> ). I am aware of F2F ( <a href="https://en.wikipedia.org/wiki/Biphase_mark_code" rel="nofollow">https://en.wikipedia.org/wiki/Biphase_mark_code</a> ) but this is a royal PITA to decode. There is also an issue of optimising bandwidth (to some sensible balance between efficiency and algorithmic complexity). The iPhone samples at 44.1 kHz; in theory each sample could transmit at least one bit depending on whether it is high or low (ie which side of zero -- theoretically of course each sample is 16 bits but trying to really optimise bandwidth to a theoretical maximum would be... what is the word... mad?), realistically I might need to use 3 sample lengths for each bit just to make sure everything gets received and a bit doesn't fall between 2 consecutive samples. Is there some open source code I can lift to do this? I would imagine software engineers have been cracking this problem since the early days of digital. I don't really want to reinvent the wheel here.
Tags
<signal-processing><modem>
Title
How to transmit binary through a single waveform
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PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. USAlexey Frunze
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1. USP i
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1. PO
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2. PO
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3. PO
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 POHow to transmit binary through a single waveform
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