RIM's Blackberry Buzz explanation

If you have a GSM phone, just put it next to your computer speakers and then call the phone from another number. You will hear some quick "gallop" noises followed by a steady buzz on the PC speakers just before the phone starts to ring.

I work for the IT department of our organization and am trying to educate the user community about the broadcast phenomona. Has anyone been able to "capture" this annoying sound on a device and converted it to a MP3 or WAV file so I can play it back to my peers and users?

John, I don't think any of the carriers up here in no man's land offer a GSM network. It is so rural up here that it isn't uncommon for a phone to only be able to pick up an analog signal when you get away from the bigger towns.

This is not a new phenomenon. In the "old days" (before cell phones) we called it "audio rectification", and it showed up wherever there was a strong AM signal. Carbon mics in telephone handsets would rectify the signal and you'd hear the station in the earpiece. Easily fixed with a cap across the mic. I have tapes recorded from disk with Radio Moscow in the background, picked up by the phono preamp. Any PN junction can rectify RF, and if the RF is strong enough the resulting audio doesn't need amplification. The output stage can act like a "crystal radio" even when turned off. Even a fairly low-power transmitter has a pretty strong signal within a few feet of radius. My old TDMA cell phone came through the car speakers like a salvo of rifle shots whenever it switched cells, and like a machine gun during a call if I got it near the cassette player. It did the same thing to a certain table radio at point-blank range even when unplugged. The rep rate for TDMA is around 50 Hz. For GSM it's 217 Hz according to the EDN link. The explanation cited in EDN refered mainly to the handset picking up its own signal either this way or via coupling of the transmitter's DC supply-current waveform into the audio sections. I don't have a Blackberry. Does the interference happen only during a call, or more routinely? If routinely, does it happen mainly in fringe areas where the set is hunting for a cell? Yes to all of these would be consistent with the above, altho it suggests the GSM set tries a lot harder than the TDMA cell phone to find a base. The TDMA phone only "fired" about once every 5 seconds or so if it couldn't find a base.

Piense, The advantage of GSM is that I can go to Europe and my phone will work. But that buzz is annoying.

Ok that makes perfect sense. My Blackberry (which is through Verizon) doesn't make the buzzing noise, but my other cell phone (courtesy of Cingular) does it all the time.

That makes sense since you mentioned that your Motorola RAZR also buzzes. I use the RAZR, but on a CDMA network, there is no buzz...