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Technology Stocks : Qualcomm Moderated Thread - please read rules before posting -- Ignore unavailable to you. Want to Upgrade?

To: samim anbarcioglu who wrote (27305)	9/30/2002 3:42:42 PM
From: propitious7	Read Replies (3) \| Respond to of 197214

QCOM solution to sync wCDMA? Doesn't anyone remember the QCOM white paper proposing a Non-GPS solution to sync wCDMA base stations. I remember that it seemed very effort- y; they described the problem and the GPS solution and then described other solutions (one I believe keyed off the radio transmission of universal time (is that the atomic clock to which you refer?). But the way they described the other solutions made you ask "Now just why would anyone want that workaround rather than using GPS". The answer, of course, is politics but they diplomatically did not examine the reasons to opt away from GPS. No one remembers this? Was I hallucinating? propitious

To: samim anbarcioglu who wrote (27305)	9/30/2002 8:16:23 PM
From: RalphCramden	Read Replies (1) \| Respond to of 197214

why not put a geosynch up as the time synch source? The fact is for synchronizing ground based systems you would not even need to launch additional satellites. You could use an extremely small amount of transponder capacity on existing satellites! Here's how it would work: Ground stations keep very accurate time, or at least standard time synched to each other. Need one ground station every 1000 miles or so. Ground stations transponded through geosynch satellites. A very narrow band could be used, a tiny fraction of a video channel. The equivalent of 1 voice channel through the satellite. The ground station monitors its own transponded downlink and measures the time-delay. It "forward corrects" the time it is sending up so that it is actually receiving the correct time on the down link. This way it can track out any time-delay changes in the atmosphere. Other stations that want time synch receive this satellite transponded signal as well. They know where the orginal ground station is, where the original trasponder is, and where they are, so they know how to correct for any difference in path delay between them and the satellite vs. between the satellite and the original ground station. This gets them to sub microsecond accuracy with sub microsecond variation across base stations using this system. Accuracy depends on how close you are to the original ground station. If you are right next to it, it is extremely accurate, as you move away, it becomes less accurate. But to reasonable (few microsec) accuracy, probably you could cover 1000 miles with each ground station. Lets up the ante. Put a few ground stations transponding through a few satellites. Each base station can pick up 2-4 of these and get a best fit solution with another increase in accuracy. Finally, the system can keep itself internally consistent by having each ground station monitoring the other transponded signals, and making adjustments to its own atomic clock based on what it sees. Or else they can all synch to one "master" transponded signal which defines the reference. If this turns out to have been a valuable patent, my employer (the bus line in NY) is going to be POd. Uh-oh. To the moon, Ralph