Comparison of the noise immunity of a LED-based multiband optoelectronic sensor when using FDMA and CDMA to code the excitation source

Abstract

We compare the noise immunity of the LED-based optoelectronic front end of a multiband spectral detection and analysis device when using FDMA and CDMA coding for the excitation source. Our results are that the two coding schemes offer comparable performance at low signal-over-noise levels, but that the CDMA approach offers a much better noise immunity in noisy environments. It is thus a much better alternative to drive the excitation source than the more common synchronous modulation approach that underlines FDMA.