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06/24/2005 Entry: "New GPS Antenna and Delay Measurements"

With help from Daun Yeagley, N8ASB, I replaced my old GPS antenna and feedline which I suspect have been failing. In its place is a new Motorola Timing 2000 antenna with about 70 feet of LMR-400 cable going into my splitter system (one 2-way HP splitter, with one port feeding about 8 feet of LMR-400 into a 4-way HP splitter which drives the two Z3801A GPSDO and the M12+ TAC-2).

With Daun's network analyzer we measured the time delay through the cable as 69.95 nanoseconds. We also measured the delay through the splitters as 47.6ns, though that measurement is a little suspect because the (relatively) narrow filters in the splitters smeared the response. So for the moment I'm assuming 118ns total delay (plus another few nanoseconds for the cable from the splitter to the receiver).

The good news is that the new antenna seems to be doing a much better job, with signal strength readings averaging at least ten units higher than before, and no signs of any signal dropouts. Thanks, Daun!