When you need GPS in your super-rugged TDS Recon handheld computer
(by Conrad H. Blickenstorfer)

The Handheld Group, located in Sweden and founded in 1997, is a worldwide suppliers of ruggedized handhelds for use in markets such as utility, military, logistics, forestry, transportation and field service. Handheld has a full lineup of rugged tablet computers and rugged industrial PDAs. One of the unique and interesting products they offer is the Kenaz DGPS receiver.

The Kenaz addresses a very specific need: what do you do when you have a Recon or Nomad handheld computer and want to use them for GPS/GIS applications without giving up any of the ruggedness and sealing that those devices carry? Those familiar with the Recon know that you can get an extended CF-Cap for it that enables the Recon to accommodate a variety of oversized add-on cards that sue the CF form factor and interface. That cap can be used in conjunction with, for example, a Holux SiRFstart III GPS card that is also available from Handheld U.S.

However, in many precision agriculture, marine, GIS mapping, surveying and a variety of other applications, a combination of ruggedness and heavy-duty commercial GPS technology is required, and that is where the Kenaz comes in. The Kenaz is based on Crescent receiver technology that is known for razor-sharp sub-meter accuracy, and being able, via COAST technology, to maintain that even during a temporary loss of the differential signal. The GPS engine used in the Kenaz code employs phase measurement and multi-path rejection that make for a very accurate and stable receiver.

Among the standard and extra-cost firmware features and options of the Crescent GPS technology used in the Kenaz are:

• 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.