So, what the heck is a "puck".
Puck is probably not the best word to use anymore. They used to look like a hockey puck but not as much anymore.
The basic premise, they are a GPS receiver that re-transmits via Bluetooth or WiFi so that devices without built-in GPS can get a position feed.
The GLO™ 2 is a GPS and GLONASS receiver that serves up Garmin caliber GPS data on the mobile device of your choice via BlueTooth® wireless technology.
www.garmin.com
Bad Elf Affordable Bluetooth GPS Receivers for Tablets & Smart Phones. Comprehensive Industry Support. High Accuracy Location for Mobile Field Data Collection.
bad-elf.com
There's reasons why you would not have or perhaps even want built-in GPS. Cost is one of course.
Also these devices have a niche in that you can put the receiver in an optimal location and the device with the application can be where it's convenient. This is actually important when precision is needed.
For example I think pilots use them often due to this. They can put the "puck" where it gets a good view of the sky and can keep their tablets where they're easier to see and use. When using GPS for true navigation like that you can't have glitches. You can test this for yourself by watching your phone as you drive around. The little blue circle that pings is telling you accuracy. When you turn it sometimes will go from a dot to a big circle and when that happens you go from a few feet of accuracy to possibly many tens of feet. Which is fine if you're moving at 5 MPH, being off 10 feet is a nuisance and you show yourself on the sidewalk instead of the street. If you're moving at 500 MPH and you get a momentary drop in resolution you might jump off your course by a thousand feet before it corrects.
BTW,
@Hulk, yes it's 100% accurate that for iPads and other Apple devices to have satellite GPS they must be cellular-capable. The Broadcom radio chip that receives GPS is integrated with the cellular modem. You do not have to activate cellular service but the device must have the chipset. Android phones generally use a different chipset.
In the case of 'Droid phones it's because it's cheaper to just include a feature you may not sell than to maintain two product lines. It's like when you buy a car and there's blank panels and wiring for options you didn't buy. Toyota builds one wiring harness for a car so the plugs are usually there behind the dash for fog lights even though you're a cheapskate. Apple and their suppliers for whatever reason made their design choices.
So anything termed "WiFi-only" with respect to Apple will only do position using their Location Services and won't work off grid where it can't see WiFi. That's where the puck comes in. It's feeding a satellite-based position into Apple's OS feature so your device doesn't know or care that's it off grid.
This, in case you're interested, is something Google started doing a long time ago and others have jumped into. Basically as they drove around doing Street View they were also checking everyone's WLAN access points and building a huge database that related RF fingerprints to geolocations. Since then it's expanded into all kinds of ways to fingerprint radios and collect data about them.
Yes, it's
huge privacy hole that you've probably never known you're leaking.
en.wikipedia.org
Did you know that laptops and other devices without GPS hardware can determine your precise physical location—with just a Wi-Fi radio? Here’s how this often-overlooked feature of modern “Location Services” works.
www.howtogeek.com
Google doesn't use StreetView cars to pick up Wi-Fi location data any more. They use your smartphones and tablets instead.
www.zdnet.com
