[time-nuts] Leica AT-303
kb8tq at n1k.org
Thu Apr 23 07:47:32 EDT 2015
I guess it comes down to “how good is good enough?”
With any L1 only system, you are up against uncorrectable ionosphere numbers in the >=10 ns range. At 3 ns meter that is a > 3 meter “variation”.
The ionosphere does tend to correlate with that big light in the sky, so averaging over multiple days can address it in a position solution. Your TBolt will still
wander around, since it’s loop time constant is << 24 hours.
If you are trying to take 12 -2/+40 ns per day down to 10 -2/+40 ns per day, then sure a ~5 mm accurate position will be better than a ~1 M location. It’s doubtful
that there will be any measurable change in the TBolt’s output as a result.
For $100, sure it’s not an expensive thing to try. I ummm ….. errrr .. seem to have a room full of antennas. My point is *not* let’s not do this. The point is that
everybody does not need to run right out and go antenna crazy (like me). The TBolt works quite well on a proper outdoor timing antenna that has a very good
view of the sky. Those antennas are nice and compact and sell for < $50.
> On Apr 23, 2015, at 3:04 AM, Mark Sims <holrum at hotmail.com> wrote:
> At least with a Tbolt, they do help... and quite a bit. When I was writing Lady Heather's precision survey code I tested it with several antennas (comparing the results to a cm level L1/L2 survey). The Leica antenna and a couple of other survey grade/choke ring antennas were, by far, the best (results with a foot or so). Cheap patch antennas were the worst (with maybe 5 foot errors).
> Some small L1 only survey grade antennas did pretty well... a couple of feet. They are about 6 inches in diameter and and inch thick and very light. I use one as my standard antenna.
> It’s not real clear that they have a significant advantage for L1 only operation with a Z3801.
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