5 ms·
> I imagine the 0xFF might be converted to 0x00 due to DC blocking capacitors/high-pass filtering, audio circuits aren't really suited for non-audible content.
by arcticbull 3y ago
> I imagine the 0xFF might be converted to 0x00 due to DC blocking capacitors/high-pass filtering, audio circuits aren't really suited for non-audible content.
Yeah, you want to generate a signal with no DC bias, something as simple as Manchester encoding will go a long way. If that's not good enough, there's NRZ or even a convolutional encoding. You also want to make sure you either send a sin wave, or if you can't do that, at least make sure your square wave frequency is high enough that it doesn't get eaten by the AC coupling capacitors.
- freeqaz 3y agoWould it be possible to get a higher quality read from using something like an Arduino's I/O pins and some bit-banged C code? I'd be curious to see what would be possible using cheap, off-the-shelf tools since a lot of people don't necessarily have an oscilloscope laying around. :P
- fodkodrasz 3y agoWithout looking up datasheets, just form the top of my head: the Arduino DAC most likely has 12 bits resolution (as common for cheap uCs), and maybe even slower sampling than a soundcard. A sound card was probably better than that even in the 1990s (say a Sound Blaster).
- aidenn0 3y agoThe original Sound Blaster could only record at 8-bit resolution at up to 12 kHz. The 2.0 could record at up to 15kHz, still 8-bit. The second generation of Sound Blaster was the first that could record at 44kHz (mono) sampling rate, but was still only 8-bits of resolution. It wasn't until the 3rd generation Sound Blaster 16 that 16-bit audio could be recorded.
- fodkodrasz 3y agoHmm, I had (false) memories of better capabilities. Though my first soundcard was an SB Pro clone, later an SB16, both almost capable :)