3 ms·

Aggravating, but par for the course, The info about the mic/amp/audio out is super interesting though.

jasongullickson 16y ago
I'm guessing it's a way to decouple the electrical connection between the audio system and the phone, to prevent the propagation of GSM/cellular radio noise.
- jrockway 16y ago
  That is what optoisolators are for, but they wouldn't help with GSM noise. (GSM noise is related to the fact that GSM divides the radio spectrum into time slices for devices to use to talk to the tower. When a phone gets its time slice, it turns the radio on. When the timeslice is over, the radio is turned off. The time slices come in intervals that are in the audio range, and thus its energy output is measurable in the audible range. Since the radio signals will induce a current in random wires, including wires in your audio amplifier, you can hear the GSM noise in your speakers. It is not related in any way to an unclean audio signal coming out of your phone; that signal has no GSM noise. It's the radio communication that induces noise in your audio equipment. So a speaker + microphone is not going to do anything except make your already-clean audio sound like shit.)
joemi 16y ago
I'm extremely skeptical that this mic/amp/audio thing is actually the case. First and foremost, Apple's iPods have (for quite a while) reserved a few pins on their dock connector for audio out, so I'd be surprised if the iPhone did not do the same. Second, this would make absolutely no sense. It would, in fact, make so little sense that I have to, sight-unseen, call bullshit on this.
- jrockway 16y ago
  I agree; this seems highly suspect. For example, how would "a" mic handle stereo audio? And why would Apple do this when pins for stereo audio already exist on the dock connector?
- bradleyland 16y ago
  You're skeptical for good reason. The author has no idea what he is talking about. There are several false statements contained in his post. The iPhone dock connector has pins for video and audio out: http://pinouts.ru/PortableDevices/ipod_pinout.shtml http://pinouts.ru/PortableDevices/ipod_pinout.shtml There is no microphone or amplification hardware in the dock.

I'm guessing it's a way to decouple the electrical connection between the audio system and the phone, to prevent the propagation of GSM/cellular radio noise.

jrockway 16y ago
That is what optoisolators are for, but they wouldn't help with GSM noise. (GSM noise is related to the fact that GSM divides the radio spectrum into time slices for devices to use to talk to the tower. When a phone gets its time slice, it turns the radio on. When the timeslice is over, the radio is turned off. The time slices come in intervals that are in the audio range, and thus its energy output is measurable in the audible range. Since the radio signals will induce a current in random wires, including wires in your audio amplifier, you can hear the GSM noise in your speakers. It is not related in any way to an unclean audio signal coming out of your phone; that signal has no GSM noise. It's the radio communication that induces noise in your audio equipment. So a speaker + microphone is not going to do anything except make your already-clean audio sound like shit.)

joemi 16y ago

I'm extremely skeptical that this mic/amp/audio thing is actually the case. First and foremost, Apple's iPods have (for quite a while) reserved a few pins on their dock connector for audio out, so I'd be surprised if the iPhone did not do the same. Second, this would make absolutely no sense. It would, in fact, make so little sense that I have to, sight-unseen, call bullshit on this.

jrockway 16y ago
I agree; this seems highly suspect. For example, how would "a" mic handle stereo audio? And why would Apple do this when pins for stereo audio already exist on the dock connector?
bradleyland 16y ago
You're skeptical for good reason. The author has no idea what he is talking about. There are several false statements contained in his post. The iPhone dock connector has pins for video and audio out: http://pinouts.ru/PortableDevices/ipod_pinout.shtml http://pinouts.ru/PortableDevices/ipod_pinout.shtml There is no microphone or amplification hardware in the dock.