Use The Serial Infrared (Ir) Connection - HP iPAQ h3800 Reference Manual

2. Follow the instructions in the installation wizard. For more
help, click the ActiveSync Help button during installation.
The information you selected will automatically synchronize
when your installation is complete.

Use the serial infrared (IR) connection

After setting up a connection with a USB or serial cable and a
cradle, synchronize your iPAQ Pocket PC and your computer
using an infrared connection if you have an infrared port or an
infrared USB adapter installed on your computer. The infrared
connection option works only on computers that have
Windows 98, Me or 2000 operating systems installed.
1. "Sync with computer" using a USB or serial cable and a
cradle.
2. Follow your computer manufacturer's instructions to install
and set up an infrared port.
3. Place your iPAQ Pocket PC and the infrared port so they are
unobstructed and within 12 inches of each other.
Reference Guide
Communicating
2–3