Comment by Xelbair | Hacker News Reader

Comment by Xelbair | Hacker News Reader

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>But it is essential. Google (and Apple) maps provide lane specific navigation directions, which are really only possible with assisted GPS. In theory GPS has the accuracy, but remember you are in a big metal box filled with electrical wires. Not to mention other applications like isle specific navigation within stores, which is made possible by bluetooth beacons.

As someone who's degree had a course in sattelite rangefinding(both code and phase), this is bullshit. Code GPS measurement should be enough for that. Especially when you already contain road data to which you can snap, and probably have access to accelerometer too which can easily improve accuracy of 'snapping'.

You don't need to get precision down to a lane on the road for purpose of navigation, you just need to 'snap' to the right road. and warn user beforehand if they need to take a turn. Just like 'dumb' GPS navigation did prior to smartphone era, while having access to less satellite systems.

> As someone who's degree had a course in sattelite rangefinding

So you are well versed in multipath reflection and why it makes unassisted GPS in urban environments with tall buildings close together almost completely unusable?

> You don't need to get precision down to a lane on the road for purpose of navigation

If you want to build an early 2000s Garmin competitor, sure. But people don't buy $1,500 pocket computers every 18 months to keep doing the same thing.

Are you saying every tomtom, garmin, etc used Bluetooth and cell services for navigation all those years?

Not to be argumentative but dedicated GPS devices didn’t always have that option. Also I’m curious: it uses triangulation off cell towers to help. I don’t see how Bluetooth helps improve accuracy. Do they map WiFi spots accurately?

No, they used other technologies, such as DGPS.

https://en.wikipedia.org/wiki/Differential_GPS

> Do they map WiFi spots accurately?

Yes, there are a number of companies that maintain BSSID->Lat/Long Databases. Skyhook is probably the biggest commercial one, and https://www.wigle.net/ the biggest open source one.

>So you are well versed in multipath reflection and why it makes unassisted GPS in urban environments with tall buildings close together almost completely unusable?

Yes, a common problem even for static measurements. Yet it worked with 'dumb' gps navigations. Btw - it's not just a p roblem in urban evirorments, especially for phase measurements - you shouldn't do precise measurements near the trees.

Just to illustrate when doing a phase measurement, under good HDOP constellation, next to the forest we barely could achieve an accuracy of half meter using Leica 1200. We measured the same reference point using total station and neighboring network of reference points.

For a reference, you could easily get sub 2cm accuracy, although below 10cm was a minimum target for that job.

>If you want to build an early 2000s Garmin competitor, sure. But people don't buy $1,500 pocket computers every 18 months to keep doing the same thing.

Sure, but it isn't a CORE REQUIREMENT for the service to function. you can degrade it, and have it work pretty well, without requiring all users to submit other tracking data sources.

> Sure, but it isn't a CORE REQUIREMENT for the service to function.

Again, you don't know Maps product roadmap. Google is taking its "Next Billion Users" initiative very seriously internally. They might be looking at ways to offer navigation using only a Wifi/Bluetooth chip so they can make Android devices as cheaply as possible.

There is also the possibility that GPS may not be functional in areas Google wants to serve. The US Government blacked out GPS over multiple states during a test. China has satellites that can rip other countries satellites out of the sky. Russia intentionally crashed an old weather satellite into an Iridium satellite just as a weird flex.

The Google product roadmap has absolutely nothing to do with whether Google maps — which we concretely know can function without network assistance — should REQUIRE said network assistance for all users at present. Yah, the results may be better with network assurance, but it should still work with out it.

This sentiment also applies to your second point — if Google wants to get some kind of navigation working without using gps in some niche market categories, that’s fine. But that shouldn’t require me, with the gps module I paid for in my expensive smartphone, to share data with Google that I don’t want them to have and they don’t technically need.

And i as an user utterly do not care about their roadmap. I care about my experience.

That still does not excuse them for requiring access to those data sources, as they can still degrade service when user does not give consent. Also there are multiple networks at the moment(USA's GPS, Russia's GLONASS, China's COMPASS/BEIDOU(forgot which was geostationary system, and which one was global),and EU's Galileo), which makes total blackout of a single area unlikely.

And quite frankly, in case of total blackout we have a bigger problems than civilian GPS navigation.

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