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Palm's Bluetooth SDIO expansion card is exciting, not only because it is one of the first mass-marketed Bluetooth devices but because it is one of the first I/O devices of any kind available in the miniscule Secure Digital form factor.

D-Link's adapter offers another intriguing mass-market application of Bluetooth technology, though the D-Link DWB-120M is a standard USB device and the drivers available for it are Mac-only. Therefore, I also tested the Palm Bluetooth card with a 3Com Bluetooth PC Card in a Dell Latitude laptop to confirm the card's cross-platform capabilities.

The first thing I noticed about the Palm Bluetooth card is its size. At 49-mm long, 24-mm wide and 2.1-mm thick, it's smaller than a postage stamp -- by far the smallest wireless-connectivity option you can add to any PDA. Still, it sticks just far enough out of a Secure Digital slot-enabled Palm that you won't want to put your Palm in your back pocket with the card inserted.

The D-Link adapter is no behemoth either: At .37 inches thick, .73 inches wide and 1.81 inches long, it looks like a copy-protection dongle and is further proof that Bluetooth technology can be small and inexpensive.

Laptop to Palm and Back to Laptop

Attached to an Apple G4 PowerBook running OS X via a USB port, the D-Link adapter worked virtually without a hitch. Hot plugging and unplugging didn't faze the Mac or adapter at all -- unplugging it while in use only interrupted the sync session in progress.

Basic setup of the adapter to allow synchronization of my Palm m500-series PDAs was a snap. Synchronization of a Palm via the Bluetooth Card was faster than with IrDA or a serial connection but was two to four times slower than direct USB, depending on the size of the files being transferred to the Palm. Connectivity was possible to around 30 feet, but data transfer speed dropped beyond 20 feet. Interestingly, turning encryption on at the client did not affect connection speed.

Results were nearly identical when syncing the Palm from the Dell laptop, though I experienced a number of hung connections that didn't occur with the D-Link-Mac solution. The Bluetooth Palm HotSync connection is accomplished via a virtual serial port, and dropping the connection speed on that port to 38400 baud solved the problem. File transfer between a PowerBook using the D-Link device and a Dell using the 3Com Bluetooth PC Card was no problem, though the measured connection speed was lower than that observed between two PowerBook/D-Link hosts -- 200 to 280 Kbps versus 400 to 520 Kbps.

I blame the occasional glitches during setup and testing on the newness of these products and the software accompanying them. Initial installation of the Bluetooth software on the PowerBook locked up the computer, but a reboot fixed the situation, and I encountered no further problems. The Palm PDAs I tested hung or committed a spontaneous soft reset several times during testing, and I occasionally encountered a delay when trying to turn off the connected Palm. But in general it was simple to use the Palm Bluetooth SDIO card to connect the PDA to the laptop wirelessly for synchronization, or to use the Bluetooth-enabled laptop as a wireless gateway for the PDA to check e-mail or browse the Web. I also had no problems setting up an easy-to-use Pico Communications' PicoBlue Internet Access Point to access e-mail and the Web wirelessly via the Palm Bluetooth SDIO card.

I realized Bluetooth had come of age the first time I checked my e-mail on a PDA using Bluetooth via an Ericsson T68 cell phone, which was still sitting in my briefcase. No more hassles with custom cables: Wireless is the way to go. The Ericsson phone worked seamlessly as a wireless gateway to dial out to an ISP via GSM (Global System for Mobile Communications). The T68 also supports higher-speed GPRS (General Packet Radio Service), so a GPRS or other data-capable cell phone with Bluetooth capability can now serve as a high-speed WAN hub for a variety of local devices seeking access to wide-area data.

A former technology editor of Network Computing, Richard Hoffman groks Web development and middleware, PDAs and wireless WANs, and leads the Web Technologies group at Fairfax County Public Schools. Send your comments on this article to him at rhoffman@nwc.com.

The Future of Bluetooth

Any application that involves short distances and relatively low I/O requirements between two or more devices is a good fit for Bluetooth. Many Bluetooth-enabled peripherals, such as the Hewlett-Packard 995c printer, Epson's Bluetooth Printer Adapter, digital video cameras and headsets are available now, and more are on the way. Microsoft has announced it will release later this year a Bluetooth-enabled keyboard, mouse and transceiver as well as integrated OS-level support in Windows XP.

So what does Bluetooth need to really take off? The devices employing it must be inexpensive and ubiquitous. The products I tested are in the ballpark: The D-Link adapter for Macs is $50 and the Bluetooth SDIO card for Palm retails at $129 or less. But to set up both ends of a PDA synchronization solution, it'll still cost more than $150. The next logical step is to have built-in, rather than added-on, chipsets and transceivers. Bluetooth will be right for the enterprise when it's not an add-on, but something that comes in the package.

On the hybrid front, at least two vendors have announced combined Bluetooth-802.11b chipsets, and Apple and Palm have broadly hinted that this kind of integration is coming soon in their new products. Apple's record for championing new technologies has been impressive: It leapt into 802.11b, USB, Firewire and DVD authoring long before the PC world took notice of these technologies. Now with other major vendors already invested, the Bluetooth market should enjoy some rapid expansion. For detailed information on the Bluetooth standard, check out: www.networkcomputing.com/1206/1206ws3.html.

Man Cannot Live by Bluetooth Alone

Bluetooth and the various flavors of 802.11 (a, b and g) can be complementary technologies. If you need long range and higher bandwidth, 802.11a and 802.11b fit the bill; using Bluetooth, the 480-Kbps to 520-Kbps maximum transfer speed and 20 feet to 30 feet maximum range that I observed in my tests won't turn anyone's head.

Bluetooth not only uses less power than 802.11b, it is theoretically simpler and calls for a smaller, less expensive chipset than 802.11b. Anyone who has carried around the bricklike combination of a Compaq iPaq, PC Card sleeve and 802.11 card only to watch battery power drop like a stunned albatross will appreciate the relatively miserly and lightweight ways of Bluetooth. Incidentally, despite the fact that they share the same frequency spectrum, the multiple Bluetooth devices and pair of 802.11b gateways I tested in close proximity did not suffer from any observable interference.