WHEN Herman Hollerith built his first mechanical tabulator in
the 1880s, it probably never occurred to him that all the
functions of his carefully crafted, single-purpose machine would
one day be transformed into a software program running on a
computer that could perform a host of other tasks as well. A
similar leap from dedicated hardware to software running on a
general-purpose device is happening in the world of radio. It
has been made possible by advances in processing power and
propelled by growing demand for wireless communication.  The
idea behind soft radios is straightforward enough. A
conventional radio can receive broadcasts only within the
limited range of frequencies that it was designed for. A soft
radio consists of a broadly tunable receiver that converts
analogue radio signals into digital data. These bits are then
processed by software that runs on a microprocessor.  Soft
radios have several advantages over their hardwired forebears.
If the radio's hardware is designed to be open-minded abou