Over the past 5 to 6 weeks in several threads, we've discussed and argued the interference issues attributed to GSM cell phones.
At this point it's probably safe to write we now understand the whys and wheresfores of the multifaceted problem and I was just about to put a closure on my files about GSM interference this weekend when 2 interesting events occurred. One is a "new" search engine referred to me by an acquaintance, the other is a refinement on the GSM inter- ference problem's cause (as item (1) below).
The acquaintance suggested I use for research- related searches for its better results. Always wanting to learn new things every day, I gave it a try. The interface is clean like Google with the additional benefit IP addresses aren't tracked.
Searching for "GSM interference problems" (as I had done with not much success or relevance with Google) claims 1.3 million results found with those 1,3 million reduced to 48 unique results ranked by relevance.
Whoa! What a pleasant surprise. Each of the 48 results was relevant and pertinent, nothing like the eleventy-seven bazillion useless hits typically returned by other search engines.
Here's what I gleaned and learned from those 48 results by IXQuick:
- the problem is specific to GSM with TDMA, not CDMA. To wit:
GSM uses TDMA (Time Division Multiple Access), so each user transmits a short burst of information at a different time, so they don't interfere with one another. A GSM phone sends one packet (burst) of data every 4.615ms, or about 217 per second. Your speakers are being interfered with at 217Hz, causing the buzzing sound.
This does not occur with CDMA (Code Division Multiple Access). In CDMA, each user gets a different code applied to his signal, so the base station can separate the users apart that way. This allows all users to transmit at the same time, so the radio isn't switching on and off at 217Hz (or any other rate in the audio spectrum).
- shielding techniques for some GSM cell phones: placing the phone atop some of the anti-static bags used for hard drives seems to work.
- some solutions for those having problems with their hearing aids:
- another good article with thoughtful user comments:
- information about Tempest:
- a new appreciation and understanding for the banning of cell phones on commercial airline flights
- interesting background information about GSM supplementing the 1994 article in comp.dcom.telecom:
NONE of the above were found in any prior searches using any of the big 5 search engines (Google, Yahoo, Bing, CUIL, Ask).
It's going to be a cold day in Hades before I return to any of the conventional Internet search engines.