Described herein are techniques for improving the signal-to-noise ratio of a wireless sensor platform. The device that interrogates a wireless sensor node (an interrogator) may be configured to determine the quantity to be measured by extracting information from multiple echoes produced in response to multiple interrogation pulses or produced due to multi-path propagation. Although different echoes may have been transformed to different extents, the echoes may share unique characteristics that are specific to the wireless sensor node that produced them. Accordingly, the SNR may be improved by keeping only portions of the received signal that exhibit such characteristics. The SNR may be further improved by summing the echoes together. In some embodiments, the echoes may be summed together in a coherent fashion, thereby producing an echo having an amplitude greater than the amplitude of each of the received echoes.