This is not too surprising as analog techniques sometimes require much, much less power, and 8-bit resolution used in these GPUs. A prism can perform a Fourier

This is not too surprising as analog techniques sometimes require much, much less power, and 8-bit resolution used in these GPUs. A prism can perform a Fourier transform more efficiently than an FPGA, as can a SAW device performing correlation. The first SAR radars used real-time optical processing with direct write to film. A simple super-heterodyne receiver will run months off a single AA battery. Try that with SDR.