converter - Extract binary data stream from audio signal -


i have binary data in stream of audio, , want decode it. here example screenshot audacity:

screenshot of data

there seems new bit of data every millisecond. means data encoded @ 1000 hz baud rate of 1000.

i can tell each packet has 20 bits (meaning takes 20 milliseconds transfer) plus 3 milliseconds of high signal. means packet resent every 23 milliseconds.

so question is, how convert binary file? going through , doing hand out of question - unless, is, you're willing :)

that's typical case of digital modulation known on-off keying (ook).

it's rather easy decode ook: apply low-pass filter cutoff frequency below 1/symbol periodicity, decimate it's output 1 value per symbol duration, , use experimentally found threshold decide what's 0 , what's 1.

you might need find exact symbol duration , symbol starts first, if want exact. that's classical synchronization problem -- in case, seems sender makes sure have sharp edge @ every symbol transition, high-pass filter signal, , clock signal, can use adjust resampler adjust sampling rate of signal going decoder (as described above).

there's nice framework that; gnu radio comes building blocks need make happen, has active community, there's gui develop signal processing application, if don't use graphical visualizations in signal processing chain, resulting application portable, it's highly optimized, , comes lot of examples.


Comments

Post a Comment

Popular posts from this blog

c# - Validate object ID from GET to POST -

i have method allows user access comment have made on site. have post method lets them update comment. my normal solution send entire comment model through, let them update it, update on database when post back. involve sending commentid through in hiddenfor , can manipulated. how can verify commentid sent in get method same i'm getting in post , not able alter comment wish? how can verify commentid sent in method same i'm getting in post? basically have validate following things in post - user logged-in user. authenticated users post comments. commentid in post , should valid commentid , should present in database. userid associated logged-in user should same userid associated comment . comment should contain userid column, can check @ time of update. to make sure update happens comment has been sent in get - hold commentid in session , in post action compare commentid value in session .
Read more

node.js - Custom Model Validator SailsJS -

when using custom model validator checks record within model. return within spread doesn't seem end control flow. //post.js model /** * custom validator **/ types: { isuservalid: function(user_id) { var promise = require('bluebird'); promise.all([ user.findone({id: user_id}) ]) .spread(function(user) { console.log(user); if (user === null || user === undefined) { console.log('failed'); return false; }else{ console.log('passed'); return true; } }); } }, my response standard validation failed response. { "error": "e_validation", "status": 400, "summary": "1 attribute invalid", "model": "post", "invalidattributes": { "owner": [ { "rule": "isuservalid", ...
Read more

php - Find a regex to take part of Email -

i have following emails need extract part from: bestellnummer xxx: 1 von xxx, 1er pack ------------- anfang der nachricht ------------- foo bar baz foo bar baz // <<<<< need text here ------------- ende der nachricht ------------- ------------- anfang der nachricht ------------- foo bar baz foo bar baz ------------- ende der nachricht ------------- there 0 unlimited occurences of ------------- anfang der nachricht ------------- ------------- ende der nachricht ------------- and i'm able extract first part regex: $re = "/------------- .*? -------------.?(.*?).?------------- .*? -------------/s"; but, i'm quite new on learning regex, i'm pretty sure there must better regex extract part (foo bar baz foo bar baz) of text between ------------- anfang der nachricht ------------- ------------- ende der nachricht ------------- as can in different languages, i'm using .? to match between hyphens. i...
Read more