
Exchange iOS contacts using sound - jptmoore
http://nibble.io/
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brudgers
If it meets the guidelines, this might make a good "Show HN".

Guidelines:
[https://news.ycombinator.com/showhn.html](https://news.ycombinator.com/showhn.html)

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danieltillett
John a very interesting approach. Could you describe how you went about this?

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jptmoore
Thanks.

A small amount of data is encoded into sound (DTMF) and this is used as a key
to retrieve more data that is passed in the background. This provides some
interesting opportunities to initiate data exchange in a broadcast fashion.

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danieltillett
Yes it certainly does. I assume that you need a pretty robust error correcting
code to ensure good data transmission. What sort of bit rate can you achieve
in a noisy environment?

I have had a play with your app and one thing I could suggest is to allow a
user to play with the system without requiring access to all contacts. I am
always reluctant to allow an unknown app access to my contacts list - I know
it is required at some point, but it could be pushed off to when the user
feels more comfortable about the app.

Anyway congratulations on doing something new.

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jptmoore
Thanks for the feedback.

By using DTMF I was able to get away without using error correction. Instead I
add checkdigits to verify the data. I am interested to explore different ways
to send about 1 second of data robustly. Data rates are very low but good
enough to transmit an audio key. I would expect it would be difficult to build
something higher than say 10 bytes/seconds over air that was robust but I am
interested in this problem. I have some work to do on the signal processing
but first want to get out the Watch version and OSX version. Of course, each
hardware has different properties in terms of speaker/microphone so it is fun
challenge!

Yeh, I understand some people won't feel comfortable granting access to
Contacts. You can say no to that dialog and still test the signal processing
aspects of the app. It will just throw an error when it tries to add the
contact.

So there are some other apps in this field using different techniques to
transmit data over sound. I mostly see blog/video posts but chirp.io is really
cool.

