{"id":9221,"date":"2012-08-24T19:28:48","date_gmt":"2012-08-25T00:28:48","guid":{"rendered":"http:\/\/blog.kenperlin.com\/?p=9221"},"modified":"2012-08-24T19:32:26","modified_gmt":"2012-08-25T00:32:26","slug":"cyclic-chirps","status":"publish","type":"post","link":"https:\/\/blog.kenperlin.com\/?p=9221","title":{"rendered":"Cyclic chirps"},"content":{"rendered":"

Thanks to Stephan Ahonen for suggesting the use of CDMA<\/a> for sending homing info to a rossum of robots<\/a>.<\/p>\n

As an alternative, maybe we can very the well known technique of sending a “chirp” in radar or sonar. In the chirp approach, rather than just sending a really short sound (and then waiting to see how long it takes to travel), you send out a continuous tone that rises in pitch over time (which makes a sawtooth pattern, since when you get to the highest pitch, you go back down to the lowest pitch and start again). Since you are sending a signal continuously, rather than just at intervals, you can get a better result.<\/p>\n

Unfortunately, as Stephan pointed out, when objects are moving toward or away from your beacon, then Doppler effects will raise or lower the perceived pitch of your tone, thereby introducing errors.<\/p>\n

Maybe instead of sending just one tone that varies linearly over time in pitch, we can send two<\/i> tones, each with a different base pitch. We make both tones wobble in pitch, varying one tone over time as a sine function and the other as a cosine function (rather than a sawtooth, our two pitches trace out a circle over time). This method will be impervious to Doppler shifts, since both tones will rise and fall together, and we only care about the difference between the two pitches.<\/p>\n

So to broadcast homing signals out to our rossum of robots, we will end up generating a total of four undulating ultrasonic tones: two from the speaker on one end of our separating rod, and two from the speaker at the other end.<\/p>\n

I’ve been searching over the internet, but so far I can’t find any examples of somebody having tried using this kind of cyclic chirp.<\/p>\n","protected":false},"excerpt":{"rendered":"

Thanks to Stephan Ahonen for suggesting the use of CDMA for sending homing info to a rossum of robots. As an alternative, maybe we can very the well known technique of sending a “chirp” in radar or sonar. In the chirp approach, rather than just sending a really short sound (and then waiting to see … Continue reading “Cyclic chirps”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/9221"}],"collection":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=9221"}],"version-history":[{"count":5,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/9221\/revisions"}],"predecessor-version":[{"id":9226,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=\/wp\/v2\/posts\/9221\/revisions\/9226"}],"wp:attachment":[{"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=9221"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=9221"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.kenperlin.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=9221"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}