241–250 of 296 posts
How are these interactive visualizations made? As a senior machine learning engineer (with only rudimentary JS skills) it would be fantastically fun to make something like these.
It's so depressing that – at some point in the future – I'm going to want a really clear and precise explanation of how GPS works and the likelihood that an internet search directs me to this excellent, clean, and ad-free blog is essentially nil.
It's so depressing that – at some point in the future – I'm going to want a really clear and precise explanation of how GPS works and the likelihood that an internet search directs me to this excellent, clean, and ad-free blog is essentially nil.
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Can you say a little more about this? This is a topic I am interested in, and I was hoping that the OP went into it, but it didn't seem like it did.
The linked article does neatly, but they use 2D projection (so it's circles not spheres). Very simplified you use the broadcasted position + timestamp of multiple GPS satellites to find your location on the earth. So for a single satellite, you can (using time-in-flight of the signal) estimate the distance to that satellite at a point in time when you received its data. Once you know the distance D to that single sat…
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Something not mentioned: the "new" L5 signal at 1176Mhz, combined with the existing L1 signal at 1575Mhz, allows the receiver to estimate the atmospheric effects and reduce the uncertainty, allowing for a much better position fix. Think centimeters instead of meters. One more thing I've wondered: the system depends on the sattelites knowing and broadcasting their exact position, but how do you determine this position…
You're spot-on, the bootstrapping is exactly why the outage took so long to recover: https://berthub.eu/articles/posts/galileo-accident/
From the article:
The outage in the ephemeris provisioning happened because simultaneously:
* The backup system was not available
* New equipment was being deployed and mishandled during an upgrade exercise
* There was an anomaly in the Galileo system reference time system
* Which was then also in a non-normal configuration
So they had to do a cold boot, which is by design slow because it focuses on high accuracy/certainty. Disappointing to read that the collaboration between the involved companies is downright bad in case of emergencies such as this. And the communication is also terrible, there's no public/official report of what exactly went wrong, why it took so long to recover, and what lessons were learned. It sounds to me that GPS being under military control is an advantage over Galileo.
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Trying to predict reflections by processing building geometry sounds very complicated and error-prone. Wouldn't it be easier to query Google Maps & Waze telemetry for impossible position jumps? Then you could make geofences where Google Play Services ignores position jumps and falls back to Wifi-based location and integrating the accelerometer.
We consider and integrate all kinds of solutions, accounting for building geometry is just one of them, and we do thorough validation to ensure it's actually helping. There's always various tradeoffs being made. Ideally, clients will be using our Fused Location Provider API [0] which fuses any (or all) of GNSS, WiFi, accel, gyro, mag... with smoothing + filtering to provide the best location possible at any time whil…
How are these interactive visualizations made? As a senior machine learning engineer (with only rudimentary JS skills) it would be fantastically fun to make something like these.
not what he/she uses, but if you are interested in these kind of things, check out https://cables.gl/ . it provides you with an in-browser, graphical, node based interface where you can just connect boxes together and it will output js-code ready to implement in your website. (disclosure: i know the dev plus am a huge fan!)
Earlier quoted context omitted.
Something not mentioned: the "new" L5 signal at 1176Mhz, combined with the existing L1 signal at 1575Mhz, allows the receiver to estimate the atmospheric effects and reduce the uncertainty, allowing for a much better position fix. Think centimeters instead of meters. One more thing I've wondered: the system depends on the sattelites knowing and broadcasting their exact position, but how do you determine this position…
Look up GPS operation control segment (OCX). Currently it's mostly Airforce and JPL, transitioning to Space Force. Lots of details published.