Suunto GPS Technical Review

The Suunto M9, X9 and G9 GPS are the first products of a completely new GPS chipset operating at a peak power level below 100mw including both rf and baseband operations. This is about three times less power than has been achieved before in comparable systems.

The complete electrical design uses two-microprocessor system with a dedicated digital signal processor taking care of the satellite tracking and the navigation solution while an ultra-low-power microprocessor handles the microsensor control and input/output routines.

Sensors

Because a stationary GPS receiver cannot tell the attitude or heading of the instrument, an electrical compass has been included. With the help of silicon-based microsensors the compass has been made to work correctly also when tilted.

The instrument also has a silicon micromechanical pressure sensor for atmospheric pressure measurement and weather prediction. In addition, the pressure sensor can be used in an altimeter mode to increase the vertical positioning resolution of the system (1 meter) in comparison to using GPS alone. The horizontal positioning accuracy is the same as in any modern GPS receiver. However, the relative measurement of position utilized in many sports applications can be much more accurate (typically of the order of a few meters) depending e.g. on changes in satellite geometry and ionospheric conditions.

Antenna

Patented features of the Suunto X9, M9 and G9 GPS include a novel GPS antenna. Unlike traditional designs in which a patch or helix antenna easily forms a protruding and often the most space-consuming component, Suunto has been able to completely integrate the antenna and the instrument case without needing any additional space. Another patented innovation in this product is to use microsensor assistance in finding the optimal visible satellites. This reduces the time to get a satellite fix and cuts the time to operate the power-hungry satellite search engine. The instrument also uses a proprietary diffractive optics design to produce a strong and even-intensity backlight for poor environmental light conditions.

Battery

Suunto's long-term involvement in ultra-low power electronics ensures that the rechargeable Li-ion battery lasts as long as needed during sports action - even though the instrument is packed with state-of-the-art microelectronics.

Menu

The user interface has a display and a logic resembling that of a cellular phone has been adopted, however, ease-of-use is greatly enhanced by sports-specific algorithms which are, in many cases, able to follow, record and analyze the sports performance automatically - without a need to press a button and go through menu selections. This is a very natural and well-proven approach for Suunto product designers because their diving computers have always worked according to that logic.

Interface

The acquired data can be transferred to a PC where it can be further analyzed using sports-specific application programs developed by Suunto. The user can also connect to Suuntosports.com where results and performance can be compared with other Suunto M9, X9 or G9 GPS owners.