Before I jump into the actual review, I want to point out what I checked on each of them:
Ease of use (power on/power off, really - there's not much else to them), ease of Bluetooth connectivity, time to connect via Bluetooth, time to acquire satellites for position, time to acquire satellites for altitude, and general user interaction. As far as acquiring goes, I used hot boots, meaning I let each one boot up fully and acquire, shut them off and booted again within a minute. I've also thrown in some manufacturer statistics like battery life (sorry, I'm not sitting there with a stopwatch to time that for you), and size.
The Dual XGPS150
Not much needs to be said for the XGPS150. Even if you've casually glanced at the product on Amazon, or anything of that sort, you'll see the raving reviews. It's really simple, compact, and easy to use. Out of the box, you get the unit, a non-slip pad, a strap (for wearing, or securing more permanently in a car/aircraft), a USB charging cable, and an adapter to charge it in a car or properly equipped aircraft, all for $99.99 (as of writing).
The small size - a 2.25" square - makes it easy to store without taking up too much space, and it has a weighted feel to it that just feels sturdy. The red circle in the middle is a large button to turn it on, with the pressure point being slightly below center. Said button takes a firm prodding with your thumb to turn it on, but if it's being stored in a pilot bag, or similar, you don't want the button to be too easy to press. Pressing and holding once again will turn it off. On the side of it, you'll find a door that hides the USB charging port and a button that switches the data format from Apple to everything else.
Holding down the button for a few seconds will bring it to life with all of the lights confirming you have, in fact, brought it out of its slumber. At that point, the appropriately blue Bluetooth light begins flashing to let you know that it's in discoverable mode, while the green GPS light flashes until it picks up the required amount of satellites. Going into your iPad's Bluetooth panel, you'll find XGPS150-[serial number]. Click to connect. Begin using it.
If you're interested, you can also download an app from the app store that allows you to see what's going on behind the scenes with the device. I'd explain further, but pictures are better:
The Garmin GLO for Aviation
Somewhat later to the game is the Garmin GLO. Reviews are just about as good for the GLO as the Dual on Amazon, and I'd expect similar from other stores. It's equally simple, easy to use, and just about the same size. Out of the box, you get the unit, a non-slip pad, a USB charging cable, and an adapter to charge it in a car or properly equipped aircraft, for $129.99 (as of writing). The regular Garmin GLO comes with the unit and the USB cable only, for $99.99.
Though it's a slightly different shape and appears larger, it's 0.0465 square inches smaller, based on the manufacturers' measurements. The size difference being negligible, it's just as portable and doesn't take much room in any bag you'd carry it in. The only button is clearly visible and functions as the power button. One press turns it on, and a press and hold will turn it off. The USB port is on the side of the unit by the power switch, in the open. Additionally, there are no special switches to switch between devices.
A press of the power button will bring it to life, and just like the XGPS150, the blue Bluetooth light will flash until it's connected to another device, and the green GPS light will flash until it has acquired enough satellites for an accurate position. In the iPad settings panel, you'll find Garmin GLO #[serial number]. Click to connect. Enjoy.
No apps for the GLO, unfortunately.
Side by Side
Looking at the above summaries, they seem like they're just about the same, and they really are. Even through my simple testing, they came up about the same by the numbers.
Here are the side by side manufacturer specs:
| Garmin GLO | Dual XGPS150 | |
| Weight | 2.12 oz | 1.8 oz |
| Size (L/W/H) | 3.04/1.65/0.70" | 2.25/2.25/0.75" |
| Battery Life | 12 Hrs | 8.5 Hrs |
| GPS | GPS/GLONASS | GPS |
| WAAS | Yes | Yes |
| Refresh | 10 Hz | >1 Hz |
Before I provide the data from my tests, I want to be very honest in that these tests were done literally in my back yard and not in some field. Both devices proved very capable of picking up signals both outside and even inside. In any case, both devices were tested in the same spot, so despite not being in the middle of an open field, the same disadvantages were present for both devices. Additionally, when testing the vertical accuracy, I gave it a +/- 10 foot buffer and stopped the clock when it reached that. I included the first altitude indication time as well.
Here are the test specs:
| Garmin GLO | Dual XGPS150 | |
| Bluetooth Connection Time | 14 sec | 5 sec |
| Position (2D) Time | 22 sec | 18 sec |
| Position (3D) Time | 30 sec | 30 sec |
| Accurate (3D) Time | 49 sec | 100 sec |
Conclusions and Other Notes
The Dual had a clear advantage in its Bluetooth time, while the Garmin seemed to fully latch on to the satellites slightly faster. The Dual satellite times may be slightly longer as my iPad seemed to be arguing with it at first. This was shown in the fact that I had to close ForeFlight and reopen it before I could see a position the first few attempts. I believe I got it sorted out for some more accurate times, but I want to put that out there. The fact that they both provided vertical data at about the same time leads me to give the Dual the benefit of the doubt on the accurate 3D time.
To be honest, you're not going to go wrong with either device. They're just about even all around, both in performance and ease of use. The Dual does have an app for the iPad so that you can check up on the device. At the very least, it's nice to know what the battery life is looking like, which is possible in the app. The lack of an app for the Garmin doesn't set it back too far, but there's some mystery in how much battery life is left if you haven't just charged it. This is also somewhat offset by the fact that the Garmin's non-slip pad has a cutout where the charger can fit, which allows you to plug it in while using it in its non-slip pad. The Dual's pad hides the charge port entirely, and even then it's hidden behind a door. You could easily remedy that issue with scissors by cutting the pad where you'd like to have access for the charger.
Both devices will have issues with heated windscreens, but most have reported good results after moving the device into the cabin. The range of Bluetooth being about 30 feet allows you to move it just about anywhere in any aircraft where you'd want an external GPS.
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Good luck in your decision making.
