RTK2b Antenna questions

Q&A forumCategory: QuestionsRTK2b Antenna questions
Ray Hallam asked 11 months ago
Hi, love your kit, wonder if you can answer a couple of questions please?
1. You state that the magnetic RTK2b antenna that comes with the basic kit is best mounted on a circular metal plate. Does this need to be solid, or can it be perforated for drainage such as this:
2. What is the best antenna you would recommend for a small base station using NTRIP over cellular rather than radio?
3. I have read that an NTRIP base station must be within a few KM of the rover, but if this is working over a cellular internet connection (4G), why does this matter? Transfer speed should be irrelevant here, is this because of environmental concerns (locking onto the same satellites, etc)?
Many thanks 🙂
replied 11 months ago

3) At 22KM you’re pretty much at the horizon, at 35KM your beyond it. Figure you add a mm of uncertainty for every KM, so at 35KM perhaps looking at a Fixed RTK CEP of around 5.5cm, and that’s probably optimistic. uBlox recommends being below 10KM, RTK Networks I’m familiar with locally have stations so that you’re typically within 7KM of one. You’re trying to maintain similar signal path experiences for Base and Rover.
End-to-End thru all interfaces, want to keep latencies under several hundred ms,at 2 Hz below 450ms. So baud rates high, hops between involved MCUs low.

2) Not sure there’d be a difference although you really want transmitting antennas pushing 1-2W away from ones receiving signals in the less than 32pW (-125 dBm to -150 dBm) range, ideally by several feet. You want the GNSS antenna to have a horizon-to-horizon view down to about 10 degrees, high enough so it’s not blocked by nearby roofs or walls.

1) I’d perhaps shoot for something more solid, you’re trying to block signals bouncing from below, and nearby reflecting surfaces. Holes here look to be a significant fraction of the working wavelengths, so probably good there. If worried about drainage pitch slightly down to the south, in Northern hemisphere.

Ray Hallam
replied 11 months ago

The perfect answer, many thanks!

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