Oznog
Active Member
I had some ideas about making a digital headset that would need to run stereo digital audio up to the headset, and also the headset mike would send digital audio back.
The problem here is that I'm limited in the types of jacks which would be desirable. Basically I'm thinking 3-pin, 1/4" phono. I wouldn't mind using 4-pin but I haven't seen them made in other than those 3.5mm minis used for hands-free cell kits and camcorder AVI cables. Too small. And DIN is undesirable because it's going to be connected and disconnected a lot and in general people won't want to screw with orienting that connector correctly to get it in.
Well, the headset would have some powerful digital circuitry, I'm looking at over 100mA. So two of those pins must be power and ground, leaving only one wire for bidirectional digital data. The current is far too high to have this be a parasite power device that rectifies power out of the digital signal. There is zero acceptability of putting a battery in the headset.
Is this even remotely possible? Serial comm doesn't normally go both ways. Even so, man 40Ksamples/sec, even 8 bit, is like 640kbaud for the upstream. It'd be much nicer to have 12 or 16 bit audio, too. The mike would be 8Ksamples/sec so the downstream is much less, but still a problem. That's kinda smokin and making it into a coordinated bidirectional scheme sounds a lot trickier. The Dallas 1-wire protocol is far, far too slow.
Any ideas? Or does this spec just rely on weapons-grade Unobtanium?
The problem here is that I'm limited in the types of jacks which would be desirable. Basically I'm thinking 3-pin, 1/4" phono. I wouldn't mind using 4-pin but I haven't seen them made in other than those 3.5mm minis used for hands-free cell kits and camcorder AVI cables. Too small. And DIN is undesirable because it's going to be connected and disconnected a lot and in general people won't want to screw with orienting that connector correctly to get it in.
Well, the headset would have some powerful digital circuitry, I'm looking at over 100mA. So two of those pins must be power and ground, leaving only one wire for bidirectional digital data. The current is far too high to have this be a parasite power device that rectifies power out of the digital signal. There is zero acceptability of putting a battery in the headset.
Is this even remotely possible? Serial comm doesn't normally go both ways. Even so, man 40Ksamples/sec, even 8 bit, is like 640kbaud for the upstream. It'd be much nicer to have 12 or 16 bit audio, too. The mike would be 8Ksamples/sec so the downstream is much less, but still a problem. That's kinda smokin and making it into a coordinated bidirectional scheme sounds a lot trickier. The Dallas 1-wire protocol is far, far too slow.
Any ideas? Or does this spec just rely on weapons-grade Unobtanium?