Subject:
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Re: Range of RCX sound production
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 18 Aug 2004 16:50:24 GMT
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Viewed:
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1141 times
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Hi Brian,
I find your question very interesting. I do not have an audio analyzer, but I
have a few ideas so you can extend your hunt.
I'm told that you can get software that lets you use your sound card as an
oscilliscope. All you need is a microphone. The question with this method
is... does your sound card sample at a high enough frequency range to measure
what you want.
A second possible place to research is to find out the make/model of the audio
component used in the RCX. I'm sure that the manufacturer would have an
amplitude/frequency curve that tells you the device's maximum frequency.
I took a quick peek at Kekoa Proudfoot's (a legend in his own time),
description of the ROM image's sound routine. If you try a frequency greater
than 20000, the ROM sound routine plays a default sound (probably the click you
hear). Also if you try a frequency less than 31Hz, you get the same default
sound.
So, even if the aduio device (could not find the part number for this) data
sheet, the RCX ROM limits you. I don't know if (using your own H8 code instead
of the ROM routine), you will damage hardware, if you exceed the limits put in
place by the ROM routines. Caveat Emptor!
Kevin
In lugnet.robotics, Brian Davis wrote:
> In the "what other weird questions can Brian Davis come up with", here's one
> I've not been able to locate on any website (including the Mindstorms Internals
> site), and I can't test it easily with my ear:
> What's the frequency range for the RCX sound production?
> By playing a tone and then increasing it till I lost the sound. It remains
> loud & clear until about 5000 Hz (PlayTone(5000,100);), and then seems to get
> softer, but is still audible at 7.3 kHz. Beyond there there's still sound being
> produced weakly (to my ears) to 15 kHz, with a distinct "click" audible between
> tones. Between 15 kHz & 17.3 kHz there is still a trace of sound, but very very
> weak and (again, to my ears) atonal. Above 17.3 kHz, I hear only the "click"
> between tones, and above 20 kHz this ceases abruptly. Note that usually I can
> hear the tone put out by a TV without a signal going in (26 kHz? IMS, & it
> probably doesn't), but the scan tone from a TV is rather loud (I don't hear it
> that way, but measuring the audio power shows it's a "loud" source).
> So, does anybody have a audio spectrum analyser handy, and can see just what
> the RCX is putting out at these very high frequencies (it would be great to have
> something like a graph of power vs. frequency).
> The low end is easier - it seems to make sound (OK, a series of clicks) down
> to right around 32 Hz, cutting off below that.
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Message has 1 Reply:
 | | Re: Range of RCX sound production
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| (...) Wow! Thanks for verifying my ears <grin>. BTW, where is the Kekoa Proudfoot's ROM description of this (is it on the Mindstorms Internals page, and I just missed it)? (...) Thanks, and for what I had in mind, it was not worth hacking H8 code (...) (20 years ago, 18-Aug-04, to lugnet.robotics)
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Message is in Reply To:
| | Range of RCX sound production
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| In the "what other weird questions can Brian Davis come up with", here's one I've not been able to locate on any website (including the Mindstorms Internals site), and I can't test it easily with my ear: What's the frequency range for the RCX sound (...) (20 years ago, 18-Aug-04, to lugnet.robotics)
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