3.15 Calculations for Distance and Calibration

This section describes the calculations to be performed for distance-bounding measurements and for frequency offset compensation. The following figure illustrates the data telegram transfer between a verifier and a prover device. For more details about the sections of the data telegram, refer to the ATA8352 Impulse-Radio Ultra-Wideband (IR-UWB) Transceiver User's Guide. The following are the parts of the data telegram:

The measurement timer, Timer1, is started, and the RX mode is activated at the end of the turnaround phase of the verifier device and counts fBB cycles. Timer1 is stopped when sufficient preamble pulses are successfully detected and accumulated (at least 128 pulses). Another timer, Timer2 is started when Timer1 is stopped and counts the number of pulses until the end of the sync word. The parameter SyncP is calculated from the total number of pulses of the preamble and sync word (303 or 351 pulses), and the pulses counted by Timer2. The position of the Leading Edge (LE) in the preamble section is calculated from the accumulated preamble pulses and determines the measured Time-of-Arrival (ToA). The position of the leading edge, LE2, is measured in the postamble, same as LE, and is used to determine the clock offset between the verifier and the prover.