As a stand-alone device, the Pocket PC can be a great personal and business tool, but its real power is released when it's connected to the outside world. As a connected device, it becomes not only a source of timely information for the Pocket PC user, but a means of sharing important information with friends and associates. Of course, all Pocket PCs come with the ability to connect to a desktop PC via sync cable and ActiveSync. But a cabled solution interferes with the incredible mobility of the device. It's the combination of a Pocket PC and a wireless data connection that delivers the greatest functionality.
In the past year, a number of new wireless options have become available to Pocket PC users, further complicating the already confusing subject of wireless connectivity. The goal of this article is to unravel this confusion.
A few words about data speed
When comparing the various wireless technologies I will be using a definition of data rates know as "bits per second" or "bps". This is a measure of the raw speed at which the wireless interface communicates. A single bit is the smallest possible piece of information. A single character of text is typically encoded into 8 bits. In addition, there is an overhead associated with any type of data communications that typically eats up another 2 bits per character. You can approximate the number of actual characters that can be transferred per second by dividing the bit rate of a particular connection by 10. Kbps and Mbps refer to 1,000 and 1,000,000 bits per second.
There are other factors that can add additional overhead. Because all wireless technologies are subject to errors, it is necessary to include some type of error checking procedure. If the wireless connection is poor, errors will result and some data will need to be re-transmitted, slowing down the data transfer rate, or "throughput." Also, many wireless technologies are asymmetrical, which means that the transfer rate in one direction is faster than in the other. Finally, many wireless networks use data compression techniques to speed up the overall throughput. But more on these subjects later.
Infrared communications
All Pocket PCs include short-range wireless capability via the built-in IrDA (infrared) port. Because a weak beam of infrared light is used to transmit the signal, two IrDA-equipped devices that are communicating must be rather close together and their IrDA ports must have a direct line of sight to each other. Formal specifications say they have a range of just under 2 meters (6 feet), but in practice the reliability of the connection tends to drop off substantially at distances of more than 1 foot.
On the Pocket PC, the data transfer speed of IrDA is limited to a maximum of 115 Kbps, which is the same speed as a standard cabled serial port. You may notice that many laptops offer "FIR" (Fast InfraRed), which supports speeds of 4 Mbps. While the Pocket PC doesn't offer such speeds, FIR is backwards compatible with standard IrDA. That means that Pocket PCs can communicate with FIR-equipped laptops.
All versions of the Pocket PC have the ability to "beam" data to other Pocket PCs via the IrDA port. In addition, the newer Pocket PC 2002 devices have the ability to swap Calendar and Contact information with Palm OS PDAs using IrDA (Screen 1). You can add this capability to the older Pocket PC 2000 devices such as the iPAQ h3600 or HP Jornada 540 series by using PeaceMaker software from Conduits (www.conduits.com).
Screen 1: The Pocket PC's IrDA port lets
you send and receive contacts, calendar appointments, files, and more to another Pocket PC or Palm OS device.
Despite the limitations of distance and alignment, infrared has the distinct advantage of being included on all handheld computers and most laptops. This often makes it the communications option of choice when copying files from one handheld to another.
Bluetooth: a short-range wireless "cable replacement"
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