24 May 2007
Synchronizing
After Mack got me XM Satellite Radio in my car as a gift a couple of years ago, it bothered me that my satellite radio experience wasn't the same as Person X's satellite radio experience. Each receiver model has a differing amount of memory and buffering in it, so just because the satellite sends us both the same signal, there's no guarantee, even if we're listening to the same channel, that we're hearing whatever song it is at the same time.
But then I got to thinking about how GPS works. Not only does GPS tell you where you are, it also tells you GPS time; i.e., the number of seconds (to some fractional precision) since midnight 5/6 JAN 1980. Note: GPS time doesn't include corrections for leap seconds and the like, so it's 10 or 15 seconds off from universal time right now.
My fantasy has become that all kinds of devices have embedded GPS receivers, so that those devices all share the same model of time. So, when the satellite radio sends me Marvin Gaye and Tammi Terrell doing "Ain't No Mountain High Enough"—perhaps the best duet in the history of recorded music—your radio and my radio play it with the same model of time. Down to the nanosecond or so.
So, when we're both be grooving to it in the car, and we roll down the windows (or put the top down—I can fantasize) our radios are in sync. Wouldn't that be sweet?
But then I got to thinking about how GPS works. Not only does GPS tell you where you are, it also tells you GPS time; i.e., the number of seconds (to some fractional precision) since midnight 5/6 JAN 1980. Note: GPS time doesn't include corrections for leap seconds and the like, so it's 10 or 15 seconds off from universal time right now.
My fantasy has become that all kinds of devices have embedded GPS receivers, so that those devices all share the same model of time. So, when the satellite radio sends me Marvin Gaye and Tammi Terrell doing "Ain't No Mountain High Enough"—perhaps the best duet in the history of recorded music—your radio and my radio play it with the same model of time. Down to the nanosecond or so.
So, when we're both be grooving to it in the car, and we roll down the windows (or put the top down—I can fantasize) our radios are in sync. Wouldn't that be sweet?
Labels: gps, synchronization, xm radio
