Software defined radio (SDR)

Updated March 28, 2012

Software defined radio has become a buzz word.

Only problem is, the technology that is required is not completely ready to support all of the claims! The ideal SDR radio architecture (antenna + ADC/DAC) only exists in ideal designs due to current technology limitations. Antennas for different applications have different requirements for gain, polarization, frequency and bandwidth. As for ADC/DAC, according to Nyquist sampling criteria, in order for the signal to be accurately depicted in the digital domain, the incident signal needs to be sampled at twice its frequency. So a 1 GHz signal will need to be sampled at 2 GHz, or 2 x 10^9 samples per second. Note that more when more bits are required the sample rate goes down, and more bits are required for more dynamic range: each additional bit ideally adds 6 dB more dynamic range. At the moment most commercial converters sample with 6 to 24 bit resolution and produce less than 1x10^6 samples per seconds. Maybe in 10 years we'll get there.

For now we'll let Josh explain it. Whoever hires this guy is going to be well positioned for the next fifty years...