Mark Lanctot wrote: > Mark Lanctot;267134 Wrote: >> 1. Unfortunately the wifi receiver isn't much more powerful. At my >> player location, it dips to a SNR of 8. There doesn't seem to be much >> difference from my beta controller, including the "bars" (I only get >> the "nub" or the first bar at this location). But it does work fine. > > Hmm, I'm not so sure now. At times it does seem a lot better, at times > about the same. It seems kind of touchy...the locations where it read 8 > SNR sometimes read 17 SNR?
The antenna was improved (according to the SD folks). I have only the beta, so I can't talk scientifically in detail of the production unit, but.... Mark's experience is normal for all 2.4gHz radios. It can be WiFi, Bluetooth, ZigBee, IEEE 802.15.4, etc. makes no matter. Up until a decade ago, no rational RF engineer would touch 2.4gHz. There is a good reason. And the reason predates the RadarRange from the 50s. Modern folks call them microwave ovens. in the 1920s and 1930s, RF engineers tried tons of frequencies before settling down on some standard bands. 600-1600kHz is AM radio. (aka 0.6 - 1.6mHz) 88-108mHz is FM radio since WW2. 54-216 mHz is TV. (with a hole for FM) Lower frequencies are desirable as it takes less power to get the same range. This is why nearly every US city has NBC on either channel 3 or channel 4. NBC got there first and staked out the channel. They tried all sorts of other bands, short wave, microwave, etc. MCI (the long distance folks) started using microwave towers. Industrial radios typically use 900mHz. But nobody wanted 2.4gHz. Because it was terrible. So it was unused until the mid-1950s when the Radarrange was invented. The reason that 2.4gHz was left unused was that it happened to be a resonant frequency for the oxygen-hydrogen bond in water molecules. So if you tried to transmit TV or radio shows, they got absorbed by any water in the air. But being absorbed really means vibrating the water molecules and converting RF energy to heat. Which is exactly what you want for a microwave oven. And it was unregulated because the TV and radio guys hated the absorbtion. So, voila, 2.4gHz was unused and unregulated because no one wanted it. Naturally, the WiFi folks adopted it. And the BlueTooth and ZigBee, ANT and other protocols. But the waves are only about 7 cm long (70mm or 2 inches) so moving an antenna 1 inch can have radically different patterns in the standing waves. These waves are created by anything with water, including people, plants, wooden furniture, wall studs, etc. The only want to make WiFi work is to have strong transmitters. Some of the next generation, WiFi 11n will move to the 5gHz band, which is still a mear fixed frequency from the evil 2.4gHz band, but its better. -- Pat Farrell http://www.pfarrell.com/ _______________________________________________ jive mailing list [email protected] http://lists.slimdevices.com/cgi-bin/mailman/listinfo/jive
