Slashdot Mirror
Software-Defined Radio Could Unify Wireless World
mjdroner writes "Technicians in Ireland are testing a device capable of skipping between incompatible wireless standards by tweaking its underlying code. The article states: 'The device can impersonate a multitude of different wireless devices since it uses reconfigurable software to carry out the tasks normally performed by static hardware. The technology promises to let future gadgets jump between frequencies and standards that currently conflict. A cellphone could, for example, automatically detect and jump to a much faster Wi-Fi network when in a local hotspot.'"
Since we're talking about Software Defined Radio, I urge everyone with an interest in the subject to look at the GNU Radio project. They have designed a front end board using generic cable TV tuners feeding an FPGA to perform some initial processing, such as decimation and filtering. The data is then transferred over USB to the host, whose software performs the demodulation and decoding. It's a fascinating project and a great stepping stone into the field.
To really get started on SDR, check out the Ten-Tec RX320D shortwave receiver. It outputs a 12 kHz-wide IF signal from the front end to an audio jack, which can then be fed to a PC soundcard. There are a number of packages that can take this data and demodulate it, including DREAM, an open source DRM (Digital Radio Mondiale) decoder which allows you to listen to the new digital shortwave transmission standard that many of the world's broadcasters are beginning to experiment with.
Karma: Excellent Birds (mostly as a result of listening to Laurie Anderson)
Antennas only affect the shape of the RF output, and the frequency range at which you can efficiently radiate.
Take some examples:
Omni-directional wifi antennas on most APs: a single stick with a fraction of the wavelength of 2.4ghz. Very simple, can do anything from SSB, AM, FM, or OFDM modulation.
Most of what software defined radios is talking about modulation changes, not frequncy changes.
The only difference between 802.11b and 802.11g is the modulation (CCK vs OFDM)