Wireless devices, from cell phones to FM radios, are effective but dumb. Most handle only one wireless format, since the others would require different radio components, adding expense and bulk. Electrical engineer Vanu Bose is using software to make wireless devices smarter. In May, the company he founded and heads, Cambridge, MA-based Vanu, demonstrated a prototype handheld able to send and receive both walkie-talkie and digital police-band signals.Vanu engineers started with a Hewlett-Packard iPaq running Linux and added a custom expansion pack. The pack contains basic radio hardware, plus electronics that convert signals into digital representations. Vanu’s software then decodes the digital signals and sends sound output to the iPaq’s built-in speaker. In reverse, transmissions are encoded into a digital waveform particular to the desired format and sent to the radio hardware for transmission. Adding a new format requires only a software upgrade. The company hopes to commercialize the software for use by police and fire departments within 18 months; consumer products that could incorporate cell-phone, pager, and wireless-data functions are “down the road,” Bose says.