3.3 Data Telegram

The data packets exchanged between the two devices have a general structure as illustrated in the following figure.
Figure 3-1. General Packet Structure
Duration:
  • PR (Preamble) tPR = 176 or 224 * PL * tADC = 45056 or 57344 * tADC
  • S (Sync Word) tS = 127 * PL * tADC = 32512 * tADC
  • DATA (Payload) tDATA = #bit *8 or * 16 * PL * tADC = #bit * 2048 or 4096 * tADC
  • PO (Postamble) tPO = 128 or 160 * PL * tADC = 32768 or 40960 * tADC

The following figure illustrates the Packet Structure for Verifier and Prover Operation.

Figure 3-2. Packet Structure for Verifier and Prover Operation
Duration:
  • TA (Turnaround) tTA = 16384 * tADC
  • PR (Preamble) tPR = 176 or 224 * PL * tADC = 45056 or 57344 * tADC
  • S (Sync Word) tS = 127 * PL * tADC = 32512 * tADC
  • SSID (identifier) tSSID = 32 * 8 or 16 * PL * tADC = 65536 or 131072 * tADC
  • RNR (4-byte nonse) tRNR4 = 32 * 8 or 16 * PL * tADC = 65536 or 131072 * tADC
  • RNR (6-byte nonse) tRNR6 = 48 * 8 or 16 * PL * tADC = 98304 or 96608 * tADC
  • RNR (8-byte nonse) tRNR8 = 64 * 8 or 16 * PL * tADC = 131072 or 262144 * tADC
  • PO (Postamble) tPO = 128 or 160 * PL * tADC = 32768 or 40960 * tADC

In comparison to the ATA8350 UWB device where the length of the preamble is 224 symbols, the ATA8352 UWB device contains a new fixed length of 176 or 224 symbols with an alternating pattern. The ATA8352 UWB device offers the user the option of implementing a data telegram with a short or long preamble based on the customer’s requirement.

The synchronization word has a fixed length of 127. In the ATA8352 UWB device, the PulseLength of the data telegram has a fixed symbol rate of 256 ADC samples. Each data bit is encoded with 8 or 16 symbols according to the default pattern for the VR, PR, RX and TX modes, and for the SSID bits in the Secure mode VR and PR:

For symbol-to-bit rate of 16-to-1:
  • Bit[0] = 1100011001011001
  • Bit[1] = 0011100110100110
For symbol-to-bit rate of 8-to-1:
  • Bit[0] = 11000110
  • Bit[1] = 00111001

The turnaround field is required to switch between Transmit and Receive modes (verifier) or from Receive to Transmit mode (prover) by enabling or disabling the internal RX and TX blocks, and has a fixed duration of 16 µs. The data packets exchanged between two devices operating with the Frequency Offset mode, using the PO field in Figure 3-1 and Figure 3-2. The symbol pattern for this postamble is similar to the preamble, but is reduced to 160 symbols. In non-Offset mode, this PO field is removed.