It could point at a river instead of the bridge over it.
It could point at an airport instead of the route around it.
It could point at a cul-de-sac, a dangerous neighborhood, a construction site, etc.
GPS fundamentally has no way of determining your direction. It was never designed for anything other than giving you a single fixed 3D location on the Earth's surface.
Marine navigation systems are the most familiar example. Many boat GPS units advertise “GPS compass” or “true heading at zero speed.” . The antennas contain two GNSS elements, fixed a known distance apart, and the direction is found using phase comparison: they look at the tiny difference in arrival time of the same satellite signal at the two separate antennas.
When you have two points determined with high enough precision you obviously have a direction and even orientation.
Your comment could have been just that. Useful information many people could find interesting. Instead you decided to sprinkle it with bile.
Have a look at images of the antennas:
https://duckduckgo.com/?q=%22GPS+compass%22+antenna&ia=image...
I do apologize for liking brutal facts - I am an engineer type.
I clicked the Furuno antenna since it looked sexy - blurb:
SC-130 features a Tri-sensor antenna that provides a high system accuracy for the heading of your vessel [for Autopilot, berthing etcetera.]. 0.25°rms
Calculating phase difference only needs a single satellite visible, so I would guess directionality can be precise in built up areas even where location is harder to fix. although I'm assuming multipath can be filtered out.
If you test phase shift to one satelite you might get good accurancy for some directions and no accurancy at all for the orthogonal directions.
So maybe not ship-length but still 1 meter sized device is way too large to put under the hood of a car let wlon in a smartphone.
Again, GPS has no provisions for orientation detection. You can hack it with few antennas significantly spaced apart (thank you again for pointing out those solutions). I think it might be easier to detect location with GPS and orientation by testing phase shift to the closest cell tower (when on land). There's nothing in GPS system thst helps with determining orientation.
And you still can't drop arrogance which gets tiresome.
Vectornav VN-310 embedded. Size: 31 x 31 x 11 mm. Power:<1.6W Weight: <15g.
I had chosen the 1m Furuno because it was pretty, not because it was a great example.
I personally suspect that the people that designed the GPS system deeply cared about using the system to calculate heading information for missiles and fighters. Unfortunately it is hard to get good information about either the system design or missile antennas. I did a quick search for information about missile antennas and learnt some stuff but I didn't find anything juicy.
Some early and experimental GPS compasses used a rotating directional antenna. The idea was to use a patch or helix antenna that has a gain pattern. Spin it, watch signal strength from satellites rise and fall, and infer orientation. A few marine and military prototypes in the 1990s did this. Once dual-antenna phase comparison became practical, that approach died.
Disclosure: I'm no expert on any of this. I just like hacking.
Interesting, however I'm doubtful about how this unit achieves compass function. It's filled to the brim with other sensors. It has gyros, accelerometers and magnetometers. I suspect that GNSS-compass is more of a marketing term for this product that integrates input from all sensors and keeps it over time for resting direction estimate.
On https://www.vectornav.com/products/detail/vn-310 they state accuracy as:
0.15° - 0.3° GNSS-Compass Heading (1m)
What is (1m)?
And in the brochure https://www.vectornav.com/docs/default-source/product-brochu... the model that advertises "GNSS-Compass Heading" has clearly visible two sockets for external antennas which I have no idea how far apart should be placed.
There's your problem: why continue to deny simple facts when you're shown them so clearly? Why should anyone ever waste their time to learn you?
> It's filled to the brim with other sensors. It has gyros, accelerometers and magnetometers
I'm guessing you don't realize how small those surface mount components are. Yet you must know your phone also contains them. The first duckduckgo result for a gyroscope was the A3G4250D in an LGA-16 package 4x4x1.1 mm. I didn't look for smaller ;)
Perhaps your employment doesn't have much to do with engineering? Facts are so awkward. I despise them!
> What is (1m)?
I've found AI too be pretty good at answering similar questions - so long as you form your prompts well.
Who's in denial? You just completely skipped commenting on clearly visible twin external antenna sockets in gnss-compass version of the unit and didn't correct your wild assumption that smartphone sized brick is all that is needed for this gnss-compass to run.
And what's that stuff about size of all other sensors? Everybody knows those don't take any space at all and that every smartphone has them. My point was that having these additional sensors in a unit that boasts inertial navigational capabilities might mean that direction is also mostly innertially tracked since the last time the sensor moved or even mostly faked with magnetometer.
I can make better guess what (1m) is than AI. It tells us that this an accurancy is achieved when you put the two external antennas 1 meter apart.
Read Wikipedia page on GPS system and try to find any single feature unique to this system (or even just not common to all radio signals) that aids with determining orientation of the reciever (while stationary). You'll find none.
If this device uses a similar technology as your phone, then I don't see it being reliable.
One of the big tricks is to realize that magnetic north (where your compass points) is usually not the same as geographic north (where maps are drawn). The adjustment is local; here, I think magnetic north is 7 degrees off from north.
In the US, the USGS topographic maps contain the required adjustment for the covered area. Not sure about Italy.
Your phone has many magnets inside, and structures that can be passively magnetized. Your local magnetic environment changes constantly.
It's a fundamental limitation of the technology, unfortunately. Generally we use GPS location as you move to infer direction and feed that back into the compass routines. It's not great but it does mostly work sometimes
After several weeks I once found the lost TV remote in the Scrabble box. However it was short lived: we had to replace it at least another five times over the next couple of years.
sejje•1mo ago
Then it's useful for everyone without dementia as well, and a bigger market is better.
For me, this is the perfect motorcycle navigation. In fact, I use an app that turns my smart watch into exactly this product--an arrow pointing to my destination at all times, no other information (distance might be nice though)
Actually, if it's for people with dementia, I think it should have a couple words on it. "Home", an actual arrow, and a distance. Two of those could be static additions, if the designer will allow their minimalism to be sacrificed for the actual goal of the product.
kotaKat•1mo ago
Have you seen the Beeline app/hardware? Pretty much a similar concept of 'follow the arrow' to get to where you need to go. https://beeline.co/
> programmable at any time
I assume a caregiver application could reprogram the location pushpin as a feature.
sejje•1mo ago
I always wonder if I'm just buying future ewaste, though. Looks like it requires their app, which requires their live servers. One acquisition away from end-of-lifed.
kotaKat•1mo ago