Posted by Matt on 3/17/2016
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Mobile GIS and GNSS Antennas
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One of the things professionals have to get used to when they switch from submeter handheld GNSS equipment to mobile GIS workflows with submeter GNSS receivers is their antenna. Whether you are using a submeter Arrow 100, iSXBlue II, or the less accurate Trimble R1 and Bad Elf Surveyor, you have to figure out how to handle their antenna’s and antenna cables (Comparison Test HERE). The important thing to keep in mind is the antenna needs to “see” as much sky as possible and preferably at all times. Below we present a few methods for working with the external antennas used with Bluetooth GNSS receivers for mobile GIS.
The standard and least expensive and cumbersome system to use is a GPS-Antenna hat. These hats have a small pouch sewn on top with a hole for the antenna cable to connect. It is beautiful in its simplicity as the antenna is higher than the user, has full sky-view at all times regardless of what the user is doing (walking, standing, climbing barbed-wire fences, etc.). Then the GNSS receiver can be carried over the shoulder in a nylon case or placed in your backpack.
For users that don’t like the GPS-Antenna hat because they need hard hats or want to work with their own large-brimmed hat, or just plain worry about fashion points in the field, there is the GPS Vest option. This is actually a very slick option as it starts with a Class-2 rated day-glow orange field vest (a requirement for many jobs) and has a few modifications for the GNSS receiver and antenna placement. There is a front pocket to hold the GNSS receiver that has a clear flap to view the indicator lights on the receiver. The antenna cable runs through the vest inside and exits to string up a short adjustable range pole to the antenna mounted on a plate at the top. The ideal method is to get the antenna a little higher than the user’s head so that it maintains full sky-view at all times. For DIY folks, you could use the short range pole and antenna mount strapped to a backpack.
Finally, there is the standard 2-meter range pole for holding the antenna. This is a must for RTK users interested in centimeter to sub-foot accuracy in their data collection. However, we have numerous clients that also utilize this method with submeter GNSS receivers for the handiness of the tablet mount. As you can see in the photos, this allows for the antenna to be mounted at the top, the receiver mounted below it or lower if preferred, and finally having the tablet mounted on the pole provides the user with one free hand during data collection. We have a full range pole setup with antenna, receiver, and mounted iPad Air that weighs less than 6 pounds utilizing a carbon-fiber range pole!
Those are the professional options, but there are always do-it-yourself options. One of our rental client’s favorite options is the backpack setup. With this option, we mount the receiver’s antenna to a metal ground plane and then attach that to the top of a short adjustable range pole. The range pole can be mounted to the side of backpacks with the water bottle holder and straps, or simply insert it into the backpack and zip it up to center it like these photos. We sell and rent this option.
We also have a simple solution for creating a clip to the bottom of receiver antennas for easily clipping it to backpack straps or other structures. You can see the full how-to video HERE and we also include this with our receiver rentals.