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SHARP66 is offline SHARP66
2014-07-18 , 00:41
Posts: 291 | Thanked: 435 times | Joined on Apr 2011 @ RO
#21
Originally Posted by chill View Post
Could range and/or accuracy be increased by attaching more powerful speakers and/or a better microphone?

One could detect movement in another room that way, too (which would certainly be a range increase) .
maybe placing a radio in the next room and using the FM transmiter with this script or without.
 

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sulu is offline sulu
2014-07-18 , 07:25
Posts: 915 | Thanked: 3,209 times | Joined on Jan 2011 @ Germany
#22
Originally Posted by chill View Post
Could range and/or accuracy be increased by attaching more powerful speakers and/or a better microphone?
Increasing range by attaching louder speakers and/or a more sensitive microphone could be reached.
For accuracy it's much harder. The key would be to measure signal delays more precisely.

Originally Posted by chill View Post
One could detect movement in another room that way, too (which would certainly be a range increase) .
That's at least doubtful. Assuming your makeshift sonar is able to manage the range, there's still the problem of obstacles like walls, door frames, furniture and so on which will cause multipath effects (i.e. signals might be reflected indirectly, causing you to measure a too long distance). The higher the distance, the worse it gets.
For a precise sonar you need a highly focused speaker and a highly focused microphone. Otherwise your sonar would be more or less omnidirectional and you won't be able to figure out where a signal came from.
 

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biketool is offline biketool
2014-07-18 , 08:04
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#23
Not sure how granular and real time the digitized sound is but it would be entirely possible to connect a ausio port, USB, or Bluetooth sound card or device for DIY sonar applications, acutally this would also work by converting the audio to RF for radar. For example a sonar transducer and receiver can be found for the small fish and depth finder devices for boats. It may require up and down conversion between our typical audio devices to the higher frequencies needed for good penetration and resolution but that is also pretty easy to do.
The question them becomes is the bandwidth provided by audio devices internal or connected sufficient to do something useful with the N900.
Going way off topic but there is no reason the audio output of one of those toy Doppler radar guns couldn't be put through bluetooth and the RF in/output run on a vertical polarized antenna with on a regulated stepper rotator reflector to make a short range real sweep scope readout radar on the N900. If only I had a real use of a small radar set.
Last edited by biketool; 2014-07-18 at 08:19.
 

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pichlo is offline pichlo
2014-07-18 , 10:18
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#24
Originally Posted by sulu View Post
Originally Posted by chill View Post
One could detect movement in another room that way, too (which would certainly be a range increase) .
That's at least doubtful.
I may be wrong but I think he meant placing both the speaker and the microphone in another room

Originally Posted by SHARP66 View Post
maybe placing a radio in the next room and using the FM transmiter with this script or without.
That is an interesting idea. May require some calibrating. If nothing else, then at least the measured distance would need to be doubled since the sound would travel only half the distance (i.e. not there and back).

Actually, the whole thing may require some calibrating one way or another. I would love to see this made into a nice GUI app with calibrating options etc.
 

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biketool is offline biketool
2014-07-18 , 10:55
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#25
In an acoustically absorptive environment like an audio recording studio with one or two hard metal or stone targets would do the trick to calibrate the sonar. An audio frequency upconverter gets you into the more useful hundreds of megahertz or even GHz frequencies, up there the resolution is higher due to the wavelength being smaller to detect small objects and doppler shift is much greater then down convert back to something common sound equipment can use.
 
chill is offline chill
2014-07-18 , 18:39
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#26
Originally Posted by pichlo View Post
I may be wrong but I think he meant placing both the speaker and the microphone in another room
Yes. :-) The increased "range" here is still the distance from the detectable object to the N900, it's just that objects very near the N900 would not be detected. One possible application is a home alarm system.
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Last edited by chill; 2014-07-18 at 20:16.
 
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nokiabot is offline nokiabot
2014-07-18 , 20:26
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#27
Why people are getting crazy ?? It wont be of much practical use aside from some fun and utlity apps games ?
currently we dont even have a app/game that uses the script as input
 
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pichlo is offline pichlo
2014-07-18 , 22:32
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#28
Originally Posted by nokiabot View Post
Why people are getting crazy ??
I wouldn't use the word "crazy". "Carried away" seems more appropriate. I do not find it surprising at all, the possibilities are virtually endless.

Originally Posted by chill View Post
One possible application is a home alarm system.
That, however, may not be as practical as it sounds, at least not without some external modifications. An ideal alarm system should be inaudible to both the normal inhabitants and the intruder. Although hearing regular pings might work as a deterrent, but then it does not even need to work as a detector
 

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sulu is offline sulu
2014-07-23 , 08:54
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#29
Originally Posted by pichlo View Post
An ideal alarm system should be inaudible to both the normal inhabitants and the intruder. Although hearing regular pings might work as a deterrent, but then it does not even need to work as a detector
You'd simply have to shift the pings to inaudible frequencies.
I don't know if infrasound is manageable with consumer electronics (it's definitely not healthy for the N900's speakers), but ultrasound is certainly possible.
Most people aren't able to hear anything beyond 16kHz and from 21kHz you should be on the safe side.
As a teenager I was able to hear frequencies between 18 and 19kHz and I could make my regular PC speaker emit these frequencies via a simple turbo pascal program.

So it should be possible to build a secret alarm system based on this sonar script - unless there's a dog nearby going crazy due to the ultrasound pings.
 

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pichlo is offline pichlo
2014-07-23 , 09:19
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#30
Originally Posted by sulu View Post
You'd simply have to shift the pings to inaudible frequencies.
Assuming the entire N900's audio chain (D/A, amplifiers, speakers...) can handle it, which I doubt. Hence "external modifications". Not to mention that the script as it is emits 16 kHz, but in a way that one can hear the low frequency "clicks" as it turns on and off. That will also require some modifications.

BTW, what happened to the OP? He turned up out of nowhere, posted one extremely useful script and disappeared without a trace.
 

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