Wireless interrogator system for SAW-identification-marks and SAW-sensor components

Threshold-based identification of wireless SAW RFID-tags with pulse position encoding

“…1 Effect of b k is similar to fading in wireless communication channels. 2 Rice derived (5) for the constant magnitude of a signal. Shmaliy proved in [21,22] that the Rice pdf (5) is also valid for time-varying magnitudes typical for SAW ID-tags.…”

“…In turn, instead of the zero OFF-bits (Off-pulses), there can appear echo traces in the presence of noise characterized in [6]. A typical received 28-bits pulse-burst ''e'' measured in [2] is shown in Fig. 1d.…”

“…In practice, the readout impulse and the retransmitted pulse are also accompanied with the environmental echoes. Moreover, the pulse-burst at the receiver detector is typically composed with the ON-bits transmitted request signal, (c) received request signal with environmental echoes [7], and (d) the tag response at the receiver detector [2].…”

“…Owing to the environmental echoes and some other factors, received by a tag the request signal ''d'' is accompanied with a number of additional impulses attenuated and propagated with different delays. It is supposed that each of the reflectors redirects the attenuated SAW (6 dB/ls delay time [2]) toward the IDT and that the latter reconverts the SAW to a single RF pulse and retransmits it to the interrogator. In practice, the readout impulse and the retransmitted pulse are also accompanied with the environmental echoes.…”

“…The slots are united into groups of several slots with one slot empty between the groups. In early designs [2], a single group of up to 32 slots was used to organize binary coding. In [3,4], four slots per group were exploited and investigated with the same aim.…”