Can a single audio channel produce a 38000 Hz signal for IR transmission?

In summary, the conversation discusses the possibility of converting an audio signal into an infrared signal and vice versa. The old Griffin patent states that this can be done by connecting two IR LEDs to two audio channels, but the question is whether it can be accomplished with just one audio channel. The speaker has conducted a study and found that it is possible, but there are discrepancies when applied to different devices. The speaker also asks for help in understanding the waveform of a phone with a "symmetrical output" and how it relates to the conversion of signals. The conversation ends with a clarification that the amplitude modulation of an IR signal occurs at a much higher frequency than audible frequencies.
  • #1
jumpjack
222
3
Sounds weird, but it is possible: you can obtain an infrared signal starting from an audio signal, and viceversa:
http://jumpjack.wordpress.com/2008/05/20/worlds-cheapest-remote-control-replicator-just-1/

But I miss something:
the old Griffin patent states that to produce a 38000 Hz signal using a 20000Hz audio output, you need to connect two IR leds to two audio channels, in such a way their frequencies sum up. Ok, it works; but I want to understand if same task can be accomplished with one single audio channel rather than two.
Somebody says it is impossibile; but I did this study:
http://www.planetmobile.it/jumpjack/ir2audio.xls"
http://www.planetmobile.it/jumpjack/immagini/ledrem.JPG"

It looks like it should work.
Actually, it DOES work, if applied to the PC; but it does not if applied to my phone: in that case, only ONE led emits IR light, and I can't understand why.

Besides, I have a phone which is said to have "symetrical output", which is quite different from standard left/right channels output:
http://pinouts.ru/CellularPhones-Nokia/nokia_pop_pinout.shtml"

I'd like to include in my Excel sheet explanation about this phone, but I can't: any help? Which waveform results at L+, L-, R+ and R- pin upon playing a 38000 Hz sinusoidal signal?
 
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  • #2
I think the jumpjack article refers to the fact that the amplitude modulation of an IR carrier signal occurs at audible frequencies. That's different from heterodyne downconversion (or upconversion).
 
  • #3
Andy Resnick said:
I think the jumpjack article refers to the fact that the amplitude modulation of an IR carrier signal occurs at audible frequencies. That's different from heterodyne downconversion (or upconversion).
no, it occurs at frequency far higher than audible: almost double! (38000 Hz rather than 20000).
So, usual audio devices cannot reproduce them; but they can reproduce half the frequency (19000 Hz), and combining two devices outputs, you can obtain 38000 Hz frequency.
 

What is sound to infrared conversion?

Sound to infrared conversion is the process of converting sound waves into infrared light waves. This is usually done using a specialized device called a microphone, which detects and converts sound waves into electrical signals. These electrical signals are then converted into infrared light waves using a special circuit or chip.

Why would someone want to convert sound to infrared?

Sound to infrared conversion is used in applications where the detection of sound waves is not possible or practical. For example, in underwater communication, sound waves do not travel very far, but infrared light can travel much further in water. So, by converting sound waves into infrared, we can communicate over longer distances in water.

How is sound to infrared conversion different from other types of signal conversion?

Sound to infrared conversion is different from other types of signal conversion because it involves converting a non-electrical signal (sound) into an electrical signal, and then into a different type of non-electrical signal (infrared). Other types of signal conversion may involve converting one type of electrical signal into another type of electrical signal.

What are some practical applications of sound to infrared conversion?

Sound to infrared conversion has many practical applications, such as in military and defense systems for long-range communication, in underwater communication systems, and in remote monitoring and surveillance systems. It is also used in some musical instruments, such as electronic wind instruments, to convert sound waves into electrical signals for amplification and processing.

Are there any drawbacks or limitations to sound to infrared conversion?

One limitation of sound to infrared conversion is that it can only be done with certain types of sound waves. For example, very low or very high frequency sound waves may not be detectable by the microphone or may not be convertible into infrared. Additionally, the quality of the converted signal may vary depending on the sensitivity and accuracy of the microphone and the conversion circuit or chip.

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