It's probably just the phone's internals doing it -- eg. tiny spikes from switching the Tx power on/off 200+ times/second. Not the actual 850/900/1800/1900Mhz RF signal.

Cheers

Yeah, I have no idea what the actual source of the noise is, I was just challenging you suggestion that only certain handsets did it

Which is very similar to what I said above...

The frequency of the signal has something to do with how noticeable it is though, at least from my experiences. I had a Sony Ericsson T610 on TMobile that ran on the 1900mhz band. A friend of mine had the T616 on Cingular running at 850mhz. Pretty much identical phone internally except for the radio. The T610 could use 900, 1800 and 1900mhz. The T616 was 850, 1800 and 1900. The notable difference? His would cause the noise on a ton of speakers while sitting in his pocket, including overhead PA speakers at his work if you listened closely. I'd have to put my phone practically ontop of unshielded wire to get any noise out of the speakers.

It's not anything I was ever concerned about until I switched to Cingular/AT&T a few years ago. Now I have to make sure my phone is across the room when using voice chat on my computer, because the mic input on my headset or USB sound card isn't isolated well enough against it, and the people I am talking to will hear it quite loudly. My speaker lines seem to be shielded well enough on the headset that I won't notice though.

The problem is the unshielded amplifier rectifying the RF signal. Any non-TX signal needs to be well below the TX level for spurious output specifications, usually at least 60dB down from the carrier.

Yeah, I was going to chime in and say that the people saying their cell phones made noise on "speakers" were using the wrong word. It's actually the phone interacting with a poorly-shielded amplifier that makes the dit-dit-dit noises. Example: If I put a cell phone in the trunk of my car near the amps, I get the dit-dit-dit noises, but not if the cell phone is in the vehicle cabin.

I also wanted to say how utterly hilarious it is that they put that little dit-dit-dit noise into Grand Theft Auto IV.

Originally I posted about the ditditdit noises in regard to the iPhone because I'd heard it was worse on it than with other GSM phones. I wasn't saying that others don't do it, mine does, but that the iPhone was particularly bad about it.

And is it just the interaction with the amp that does it? On my phone, if I manipulate the cable coming from it it seems to help quite a bit...

A friend of mine who used to live very near a mini-cab company would occasionally hear their dispatcher faintly over his speakers which were plugged-in to a hifi amplifier that was switched off, but I imagine that that was with much higher transmit power, and much dirtier (probably illegally so) sideband than any mobile phone.

Peter

What I'm saying is that there's not enough energy in the cellular data signal to move a speaker cone on its own. (God I hope not, or else the folks worried about cellphone cancer might not be so crazy after all.) So saying that the cellphone makes interference noise with your "speaker" is a misnomer.

In order to get those dit-dit-dit noises to come out of a speaker, the phone has to be causing the RF interference at the amplifier stage or somewhere prior to the amplifier stage. For instance, if it is near the amplifier circuitry, near the line input circuitry, or near a live microphone transducer.

In many cases all of those circuits are near each other anyway. For example with self-powered speakers, with a car stereo, or with a computer laptop speaker system. So it *seems* like the phone is interfering with the speakers.

I'm sure if you induce enough RF energy onto the cable feeding a speaker then it will move. Bear in mind, at higher frequencies you don't need to move a cone much either.

A friend of mine used to set burglar alarms off with his in car CB rig which was attached to a massive burner. It got to the point where I used to try and cover my privates every time he keyed up for fear of radiating something I might need later on.

People will say speakers as they're the bits that make the noise. Just smile and nod safe in the knowledge that you know more than they do. Most people hate being corrected.

What I haven't heard anyone mention is whether or not you'll finally be able to wirelessly sync with the new iPhone OS. You can buy apps wirelessly, but how about syncing contacts, music, photos, etc? I'm not talking about the push capabilities of MobileMe now.

It would be cool to be able browse your iTunes running on a machine within your network as if you were browsing music on the device itself. Then pick the songs to copy over directly from within that iPhone UI . You know, think different, sync different. Hopefully this is something that can be implemented in the realm of a third-party application. Though I have my doubts such apps will be able to actually touch the music storage area without breaking at least the development agreement.

But back to push... It would be nice to also support push among your own networked devices without the need for Apple's own server in the "clouds." BTW, what pretentious asshat coined that term? Probably some twitter-using good-for-nothing. Syncing without having to press a sync button or fire up special software manually on your Mac (or PC I suppose).

Aside from Exchange Server and MobileMe, I don't think that's in the cards. I'm sure they would have said so if that were made a feature.

I wonder if there's a specific reason for that? Perhaps they don't want to have to answer for the speed, reliability, and battery life issues that would inevitably come up when synching music and photos over 802.11 wireless.

Don't you have to pay for .Mac (and now Mobile Me)?

Or maybe they don't mean that the phone is directly affecting the speaker cones and are just saying it that way for simplicity.

Also very true.....

So no background applications...

What if I wanted to write a small app that sat in the background and posted my latitude and longitude to my website every 5 minutes, but would still allow me to surf the web and make calls.

Can something like this be done at all on the iPhone? I don't imagine it does cron jobs

Both Exchange and MobileMe are about syncing schedules and contact information. The first to a group server and the second to a personal offsite "cloud." Neither of which I could care less about.

I have it on good authority that wireless music sync is definitely not in the cards. A shame that with such a "connected" wireless device, you have to attach a 1990's USB cable to it to get any of your own information/content onto it.

I can't fathom the thought process at the Apple design meetings about this. You can wirelessly purchase music, but you can't wirelessly transfer music to the iPhone that you've previously purchased with iTunes on your computer. What a backwards little device in so many respects.

This is what I was talking about. I can rip the thing to shreds by finding all its shortcomings, but that doesn't change my opinion about it doing exceptionally well in the marketplace.

I think it's still missing some features before I jump on it. I'll also need to see it jailbroken and unlocked. There's no way I'm signing a 3 year contract with anyone, let alone one of the worst companies in Canada (worst in treatment of the consumer and contract violations).

The unofficial SDK would let you do that but I don't know whether the official SDK will.

Your battery life would probably suck though. The non 3G iPhone relied on it going to sleep regularly and shutting down EDGE and WiFi.

Battery life I'm not worried about since I'd only be running this while in the car with the phone plugged in to a power source.

Thanks, maybe I'll give it a try.

That said...will waking up every 5 minutes just long enough to do an http post really eat that much extra battery?

I think the kind of background applications people wanted to write involved a temporal resolution finer than five minutes.

But to answer your question: Yeah, it really would eat battery. If my iPod Touch is any indication of battery life and its usage with wifi, what you describe would mean that if I charged the player before I went to bed, I'd need to charge it again before I could it to listen to music during my morning jog.

I know that your particular application wouldn't be left running while you slept. But some of the background apps people want to make *would*. Hence it's a big deal.

Anecdote:

One time about 12 years ago I had a rental car driving to DC to do some work. I had brought along a portable CD player with cassette adapter so that I could listen to music on the trip up. I also had a cell phone with me, a MicroTAC that I kept in a pocket in the dash below the radio. People were calling me throughout my trip. I quickly noticed the ditditdit induced in the cassette adapter cable before the phone would ring.

However, it took me at least a dozen calls before I realized that somehow the portable CD player was pausing on its own each time I got a call. I can only imagine that the voltage induced in the cable got sent back to the CD player over the headphone port it was plugged into and caused it to freak out. It would be really neat to think that somehow some engineer got the bright idea of watching for that signal and automatically pausing the player, but I imagine that it was simply fortuitous.

Wifi kills the iPhone battery real quick. So by going cableless for music syncs, you get all your new music right about the time you need to dig out the cable to charge anyhow.

I do wish I could sync other stuff wirelessly though. Mobile Me should do that well enough when it comes out, though I do wish I could get the same capabilities on my own servers.


There will be support for background notifications in September. It doesn't sound like your idea would work under this setup though.

well...I thought about that. It could at least notify me when it's time for the next update so I could open the app.

Kinda crappy solution, but better than nothing.