The fast-growing M2M market presents a series of wireless design challenges (part 4)
Check that positioning receivers are automotive-grade, support dead reckoning, and can be plugged into the vehicle's CAN bus to acquire the data. Also, ensue that
they can interface directly with vehicle sensors such as gyros and odometers and that the vendor offers an evaluation environment to speed industrial computer product development.
Indoor positioning is possible by combining satellite and cellular data
Where an approximate indoor position needs to be established, combining a satellite receiver with a wireless modem overcomes the problem of satellite signals being blocked by walls or other obstructions. This hybrid solution exploits the visibility of 2G or 3G cells because GSM or UMTS signals easily penetrate walls. Where the boundaries of visible mobile cells are known, an approximate position can be calculated from knowing where the cells overlap. This approach needs a wireless connection to an external service, similar to assisted positioning. Check that the positioning receiver and wireless COMe Module modem supplier can offer such a solution, and that it's proven and provides an online industrial computer service. It's also important to ensure that the system's accuracy is adequate.
Positioning system compatibility
Until recently, embedded system GPS was the only system designers needed to consider. Now, there's Russia's GLONASS, Japan's QZSS, China's BeiDou, and Europe's Galileo. Compatibility with GPS plus at least one other satellite system will be needed to increase system reliability and accuracy, and to fulfill regional on-board computer government mandates for compatibility with their own systems. Parallel operation that uses two systems simultaneously may be part of the specification. An example is Russia's new embedded system ERA-GLONASS vehicle emergency call system that requires GLONASS compatibility. Look for GPS/GNSS receivers that provide multi-GNSS support and provide parallel GPS/GLONASS or GPS/BeiDou reception.
These are just some of the considerations when adding wireless connectivity to M2M products. Remember that many new standards, both wireless and positioning, are in transition. It's important to consider the on-board computer product's operation over its lifetime and which markets it will serve. Also, consider whether it's important to include design support for next-generation performance and industrial computer network coverage, or opt to design for easy upgradeability of products in the field.