SAW sensor correlator system performance parameters

There has been little published data on spread spectrum SAW RFID correlator receiver performance, since most approaches published have used an FMCW system. The purpose of this paper is to discuss issues related specifically to correlator receiver performance parameters with respect to range, detection, and noise. The minimum detectable signal (MDS) at the ADC is used as the measure for prediction of the maximum range. The loop gain of the system, MDS, noise and processing gain bound the predicted achievable range for a correlator receiver. It will be shown that in a correlator receiver nano- to micro-joules of energy can obtain ranges greater than 50 meters, dependent on the key system parameters. A model is developed for prediction of the maximum range as a function of center frequency, output signal and power, MDS, synchronous interrogation, and loop gain. From the predictions, it appears feasible to have a sensor range of over 100 meters with modest interrogation energy in a pulsed correlator system.