preamble length as reported in the RXPSR field but also uses the Preamble Accumulation Count value
reported in the RXPACC field of Register file: 0x10 – RX Frame Information Register. Table 8 presents the
resulting preamble length used for the ACK frame as a function of RXPSR and RXPACC fields.
Table 8: Auto-ACK preamble length depending on RXPSR and RXPACC
PSR carried in PHR &
reported in RXPSR
PSR accumulated and
reported in the RXPACC value
Resultant Preamble
Length of auto ACK
Table 8 relates to standard frames. In extended length frame mode, (as described in section 3.4 - Extended
Length Data Frames), just the Preamble Accumulation Count value (reported in the RXPACC field of Register
file: 0x10 – RX Frame Information Register) is used to determine the preamble length of the ACK. Table 9
presents the preamble lengths used for the ACK frame in extended length frame mode as a function of the
RXPACC field.
Table 9: Auto-ACK preamble length selection in extended length frames mode
PSR accumulated and
reported in the RXPACC value
Resultant Preamble
Length of auto ACK
NOTE *: These (asterisked) short preamble lengths will not be received by the DW1000. Use cases where
this is likely to occur frequently should be avoided by one of the following strategies: (a) using a longer
preamble for retransmission when no ACK is received, (b) not using the extended length frames mode, or, (c)
by using the host microprocessor to generate the ACK in place of the DW1000’s auto-ACK feature.
NOTE 1: It is possible for the Preamble Accumulation Count value (reported in the RXPACC field of Register
file: 0x10 – RX Frame Information Register) to be significantly shorter than the transmitted preamble length,
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