ottivo:
Please correct me if I'm misstaken but,
The directivity factor, or the "narrowness" of the beam is dependent of the wavelength for a given geometry.
Once upon a time, we had a carrierfreq. and a baseband-signal for radio where the bandwidth of the baseband-signal << carrier-frequency and we used FM/AM modulation, thus the beam had about the same directivity over the used frequency band for the radio transmission and everything worked fine.
For microphones you solved the problem with shoot-gun microphones like this to create acoustic delay-lines.
But the penalty of such construction in general is the frequency response and the frequrncy dependent directivity factor.
For Audio we would like to have a microphone that covers 20Hz-20kHz, at least for human speech we need to cover the voice-formants 300-3800 Hz + the consonants, thus 300 Hz- 8 kHz.
If we now try to create a "zoom"-microphone we get the problem with the directivity since the frequency covers over one decade.
A solution to achieve a beam with a frequency-independent narrowness, and a final result that has a flat frequency response, is to apply a filter-function to each signal prior addition - and in the end make a compensation with a filter if necessary.
Simpe array-antennes for EM. could be used a long time ago, since it was simple to construct a short-time delay-paths, and the bandwidth of the baseband was very narrow.
So who wants to make one of these?
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Probably not the most confused programmer anymore on the XCORE forum.
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very good point! audible signal is quite wide in this sense.lilltroll wrote:...
bandwidth of the baseband was very narrow.
edit1: quote code inserted wrong reference
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I was aware of phased array sound generation almost 30 years ago. A company near where I was working had some systems. It was a spin-off from the sound system they had on the helicopters in 'Nam (See Apocalypse Now). Also check out http://www.farsounder.com/ for a 10x10 sonar array.