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Juniper Archer Field PC plus Hemisphere GPS XF101
Sub-meter DGPS integrates with ultra-rugged PDA
(by Conrad H. Blickenstorfer)
Juniper Systems of Logan, Utah, offers the ultra-rugged Archer Field PC for applications in numerous vertical markets from agriculture to forestry to meter reading/data collection to wildlife resources and more. The Archer—which provides full Windows Mobile functionality and excellent connectivity in a virtually indestructable device—is now available with a special version of the Hemisphere GPS XF101 receiver that fully integrates with the handheld to deliver sub-meter DGPS to location-based applications in the most demanding environments.
The Hemisphere GPS XF101 essentially adds very high DGPS accuracy to the Archer handheld computer, making it suitable for field data collection and other GPS/GIS applications that require accurate geospatial information. Those familiar with the Archer know that the platform is designed to accommodate "extended cap" systems that may include a variety of interface, data collection and peripheral technology to augment the base device. Best of all, these extended caps do not reduce the Archer's stellar IP67 ingress protection rating.
With the Archer already capable of accommodating third-party GPS modules under its optional Universal Cap, where does the XF101 fit in? The answer is that many precision field data collection applications require heavy-duty commercial GPS technology with features and performance that go well beyond what standard GPS modules can deliver. The Hemisphere GPS XF101 is designed precisely for those kinds of applications. It is based on Crescent receiver technology that is known for reliable sub-meter accuracy that can be maintained, via COAST technology, even during temporary differential signal loss. The GPS engine used in the XF101 code employs phase measurement and multi-path rejection that make for a very accurate and stable receiver.
Here are the basic advantages of the XF101:
- Fully integrated into the design of the Archer host handheld
- Low power consumption to conserve handheld battery power
- Easy to use (just connect and go)
- Won't affect overall ruggedness and sealing of the Archer
- Optional extenal antenna for additional accuracy
And these are the standard and extra-cost firmware features and options of the Crescent GPS technology used in the XF101:
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COAST Technology, which facilitates minimal position drift during temporary differential signal corrections loss and maintains sub-meter accuracy for up to 40 minutes after the signal loss.
- RTK, or Real Time Kinematic, satellite navigation, which offers the same sub-inch accuracy as dual frequency systems, but at much lower cost (RTK needs a base station, rover, and correction transmission at a one-time activation fee).
- L-Dif technology, that provides sub-foot accuracy and a variety of exclusive L-Fid- exclusive techniques (needs a base station, rover, and correction transmission at a one-time activation fee).
- e-Dif Extended Differential, which limits position drift when differential corrections are unavailable and has recalibration options to regain absolute accuracy at a reference location. There is a one-time activation fee, but no subscription costs.
- RTCM Base Station functionality that essentially converts the GPS receiver into a differential Real Time Correction Messages station.
The Hemisphere GPS XF101 comes in two parts (see picture below). There's a special CF adapter that replaces the standard Archer cap, and then there is the completely sealed Hemisphere XF101 receiver itself. The connection between the two is via ultra-reliable spring-loaded pins. By default, the XF101 connects to the device on COM2 at a baud rate of 57600. It can be used with a wide variety of mapping, GIS, surveying and other GPS-based software available via Juniper Systems or from third parties. Mobile GIS applications such as ESRI ArcPad and OnPoz GNSS Driver are fully supported.
As listed above, the XF101 is capable of centimeter accuracy when using it with an external antenna while employing standard survey techniques and software. The unit's internal smart antenna is sufficient for most applications. For applications where additional accuracy is required or where the unit is obstructed, a sealed external SubMiniature B SMB snap-on connector accommodates the external antenna.
The Archer Field PC
The Archer rugged PDA is one tough handheld. Here are the specs that matter:
- If push comes to shove, you can operate the Archer in temperatures as low as -22 degrees Fahrenheit and as high as 130 degrees. Bluetooth only works down to about -4 degrees, but the rest of the Archer works just fine in bone-chilling temperatures. And 130 degrees is about as hot as it gets in places where humans can work and survive.
- As far as the ever-popular drop testing goes, the Archer survives multiple drops from five feet onto concrete. And not just in nice lab conditions. It'll survive those drops throughout its operating temperature range.
- For ingress protection, the Archer rates a stellar IP67. The first number stands for protection against solids. 6 is as high as it gets, and it means the unit is totally protected against the finest dust. The second number is for the degree of protection from liquids. That scale goes from 0 (no protection) to 8 (totally immune to water, even indefinite immersion). A 7 means the device is protected against the effects of immersion into water, up to a certain extent. For the Archer, that means it can survive half an hour or so under a meter, 3.3 feet, of water.
- A special version of the Archer has been certified as "non-incendive" for use in Class I Div 2 areas as well. That doesn't make it intrinsically safe but means it won't arc or spark and doesn't have hot surfaces, all of which can make a device a hazard in certain applications.
- The Archer has also been tested according to the MIL-STD-810F procedures regarding water, humidity, sand and dust, vibration, altitude, shock, high temperature, low temperature, temperature shock and so on. Juniper Systems can supply details.
Protection through intelligent engineering
How did Juniper Systems achieve such stellar ruggedness specs? By adding a whole lot more clever engineering than meets the eye. Don't let the friendly "high visibility" orange pumpkin exterior of the Archer fool you (the orange version is for maximum visibility; a gray one is available also). It's just very well integrated padding and protection. Remove the plastic/rubber elastomer overmold by simply undoing a grand total of six screws and you find underneath an entirely more serious looking piece of equipment.
Below are the pieces of the base Archer Field PC laid out: You can see the orange elastomer parts that provide protection, the backside of the magnesium core, the battery that seals tightly against the contacts, and the rubber plug/handstrap assembly.
Above you can see the bare core of the Archer rugged PDA. It's a rock-solid, brilliantly engineered magnesium case that seems milled from a solid block of metal. How does the Archer manage a IP67 rating when it has all those ports and expansion slots? From what we can tell, by separating things into different compartments. The vulnerable interior with all the electronics is housed inside the magnesium case. The ports at the bottom of the device are mounted in a plastic block screwed onto the magnesium housing. The ports are protected, but not totally sealed, by thick rubber plugs. Even underwater, while a bit of water may get into the connectors, it won't get inside the case because the interface between the connector block and the magnesium housing is sealed.
The situation is different on top of the unit where the two expansion slots are. There are electronics in there and they need to stay dry. Sealing is provided by the elastomer top cap. An o-ring approach (o-ring in principle; Juniper is actually using sealing plates) is used to keep water out, so make sure the top cap is securely screwed down after you've taken it off to insert a card. And make sure nothing is clinging to the sealing surface as that would allow water to penetrate.
The battery compartment is not sealed, so how is water kept from reaching the contacts? Once again, Juniper's engineers used the o-ring approach. The contacts have a rubber seal around them that presses against a flat surface on the battery, keeping water out.
Another smart aspect of this approach is that should the outer padding get cut or ripped, it can be replaced easily and inexpensively. The same goes for the rubber flap with the four individual protective plugs.
Technology
The Archer is powered by the 520MHxz version of the Marvell PXA270 processor. There is 128MB of RAM and 512MB of Flash. The transflective display measures 3.5 inches diagonally and uses the ubiquitous 240 x 320 pixel resolution. The display is just bright enough and is outdoor-viewable, though there is more glare than we like. On the software side, Juniper now uses Windows Mobile 6.1. Compared to the earlier Windows Mobile 5.0 used in older Archers, this provides a variety of improvements, including enhanced security and control, support of the Microsoft Office 2007 file formats in the mobile apps, multiple network connections, new tools and control panels, and a variety of other improvements. Windows Mobile remains a stable, time-tested operating platform with numerous software development tools and a large library of applications.
The Archer has both a Compact Flash Type I/II card slot as well as a SDIO slot. Both are user-accessible after undoing two Philips head screws and removing the top elastomer cap. If you use the Archer with the Hemisphere GPS, the CF Card slot is used by the GPS.
On the interface side, there is a standard 9-pin RS232 port, and two USB ports. One of them is a USB host, using a Mini-A jack, to control other devices. The other is a USB client, using a Mini-B jack, for synchronization with desktop or notebook PCs. The power jack is located next to the USB client. All ports have individual protective rubber plugs.
The Archer can be ordered with integrated Bluetooth Class II. Wireless communication (WiFi or wireless cellular modems) is via SD or CF cards, so if you need WiFi in a Hemisphere GPS-equipped Archer, you need a WiFi SDIO card.
Controls and navigation
The Archer rugged PDA has a sealed resistive touch screen, a 4-way navigation disc, and six hardware buttons. The hardware button, three each on either side of the navigation disc, are backlit and labeled, but they can be reassigned. As is, the buttons bring up the Windows Start menu, the Applications Manager, the Today screen and context menus. There is also an enter button, and a slightly recessed one that turns the device on and off. The touch screen can be operated either with the supplied 4.6-inch long stylus that stows away into a garage on the upper left side of the computer, or with any other stylus or even finger. There are no additional hardware controls.
Size and Ergonomics
Being an ultra-rugged device, the Archer Field PC is larger and heavier than a consumer-grade Pocket PC. The bare Archer unit is 3.5 inches wide, 6.5 inches tall, and about 1.7 inches thick. The computer weighs just over a pound, light enough to carry for hours. The Hemisphere GPS adds about four inches and half a pound.
Except for users with very small hands, ergonomics are excellent. The Archer fits perfectly into a hand and the elastomer protective cladding provides a good grip. An elastic handstrap mounted on the back of the device provides extra security against dropping.
The hardware controls require a firm push and provide tactile feedback. Their backlight is adjustable.
The protective rubber plugs at the bottom can be a bit obstreperous. They need to be guided and require a firm push to be seated firmly into place.
Bottom Line
The Juniper Systems Archer Field PC is a very intelligent design that combines a rock-solid magnesium core with easily-replaceable exterior elastomer protection, making for both superior durability and above-average connectivity and onboard expansion. The device is ergonomically designed, too, and its strong battery easily lasts a full shift or even two. Electronics and software are tried and field-proven, as is the transmissive 240 x 320 pixel display.
The Hemisphere XF101 DGPS receiver, designed specifically to seamlessly integrate with the Archer, adds sub-meter accuracy and commercial-grade GPS features for applications that require very precise geospatial information.
Overall, the Archer Field PC is a superbly designed, ultra-rugged handheld computer. It's tough enough to handle virtually any abuse, yet small enough to be carried anywhere. This and its powerful battery make the Archer a convincing choice for any number of demanding field applications.
The total cost of the Archer Field PC and the Hemisphere GPS XF101 is less than US$2,500, making for an excellent value.
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