Making regular GPS ultra-precise

NoiseBert69 12 minutes ago | parent | next [-]

Galileo HAS allows precision down to 30cm with enough integration time. Without additional external data.

For free.

Receivers slowly hitting the market now - a year ago this was only receivable by SDR-driven devices.

"with enough integration time" — the article is about live navigation, which generally can't afford that.

	▲	NoiseBert69 7 minutes ago \| parent [-]
		With SBAS 1-2m precision can be done easily in the US and EU. Most of the time enough for any navigational use. Pretty much all GPS/Galileo receivers are able to receive and decode these overlays.

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eqvinox an hour ago | parent | prev | next [-]

Nothing in this article is new, and the problem with RTK has always been the (unpaid) availability of reference stations. Good on them for trying to make a package of it, but maybe this "news" site could've used a bit less unchecked enthusiasm.

Also, RTK is the opposite of "regular" GPS, it's generally considered a "special" usage mode of GPS.

And discussing urban canyons with no mention of QZSS?

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Havoc 2 hours ago | parent | prev | next [-]

Why don’t cities have ground beacons for this?

Much cheaper than satellites and would be guaranteed to see heavy use

	▲	myself248 34 minutes ago \| parent \| next [-]
		Some places have free RTK networks their citizens can use. Michigan's department of transportation, for instance, runs a CORS network that anyone can request access to. (At least as far as I can tell. The signup form doesn't ask for affiliation or payment.) It's just distributed over the internet, the assumption being that you probably have internet access already. One of these days I'll figure out how to set up a free NTRIP caster on my Galmon station so it can do double-duty. The trick then is advertising and discovery. It would be lovely to have, say, a standard wifi SSID or a standard LORA channel that your local corrections network would broadcast on. That way you could have a large number of client devices not each needing their own internet access SIM card or whatever. I wonder if the corrections stream would fit into an FM RDS payload or something. Trouble is, there's so much money in the L-band corrections services, and so little money in replacing them for free... Oh, yeah, the cryptocurrency folks have weighed in, there's a thing called "goodnet" which appears to be microtransactions in exchange for NTRIP streams over some medium. I haven't looked further into it.
	▲	eqvinox an hour ago \| parent \| prev [-]
		That's kinda what RTK does, you have a ground station and transfer correction data for the visible satellites from it to your GNSS receiver. It doesn't transmit a GNSS signal itself but functionally the effect is vaguely comparable to a "satellite on the ground", without interfering on the actual signals.

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Tepix 2 hours ago | parent | prev | next [-]

Another option to get more precise positioning is to switch from GPS to Galileo.

Galileo generally offers better civilian accuracy than GPS because it uses modern signal structures with better resistance to multipath and interference and provides dual-frequency signals (E1 + E5) to all users, which mitigates ionospheric errors.

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ktosobcy 2 hours ago | parent [-]

most software now uses multiple GNSS at the same time?

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Podrod 2 hours ago | parent [-]

Yeah, according to the 'GPS Test' Android app my phone is picking up and using GNSS signals from GPS, Galileo, GLOSNAS, and Beidou sats.

	▲	UltraSane 28 minutes ago \| parent [-]
		Man I remember getting my first GPS receiver in the 90s and now are phones can use so many sats.

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mavhc an hour ago | parent | prev [-]

Don't cars also measure their wheel movements to increase location accuracy?

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eqvinox an hour ago | parent [-]

Almost, they use accelerometers and gyros, 'dead reckoning' is the keyword to look for. The wheels are a bit unreliable because the diameter changes slightly with pressure and temperature.

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willis936 an hour ago | parent [-]

Wheels are still used for legal telemetry: speedometer and odometer.

	▲	eqvinox 13 minutes ago \| parent [-]
		The legal requirements on that (in most places) are that the speedometer is in something like a -0%/+10% range, i.e. never shows lower than you're actually driving. Not only is that not helpful for navigation (but you could compensate that/shift the error window), but the precision is also pretty low (which you can't easily compensate). (There are two precision problems here — tyre diameter changes slighly while you're driving, but also it's not precise to begin with before you even turn on the car, due to tyre wear.) You'd need to do something like calibrating wheel speed data while you have good GNSS reception, then you could use it for dead reckoning. But accelerometers and gyros are cheap… P.S.: I didn't say wheel speed data isn't used, just that it wouldn't be precise enough on its own.