DW1000 User Manual
© Decawave Ltd 2017
Version 2.12
Page 95 of 242
Field
Description of fields within Register file: 0x10 – RX Frame Information Register
RXPSR
reg:10:00
bits:19,18
RX Preamble Repetition. This field reports the received frame preamble length as signalled in
the frame’s PHR (see 10.4 for details). The values of these two bits are defined by the standard
as:
00 = 16 symbols, 01 = 64 symbols, 10= 1024 symbols, and, 11= 4096 symbols
In addition to these standard preamble lengths, the DW1000 also supports the transmission of
non-standard preamble lengths. These non-standard lengths cannot be signalled in the PHR;
instead the DW1000 gives an estimate of the preamble length based on the RXPSR from the
PHR and the RXPACC value. The estimate is reported using RXPSR and RXNSPL fields together
as per Table 17above.
This value is updated when a good PHR is detected (when the RXPHD status bit is set).
RXPACC
reg:10:00
bits:31–20
Preamble Accumulation Count. This reports the number of symbols of preamble accumulated.
This may be used to estimate the length of TX preamble received and also during diagnostics as
an aid to interpreting the accumulator data.
It is possible for this count to be a little larger than the transmitted preamble length, because
of very early detection of preamble and because the accumulation count may include
accumulation that continues through the SFD (until the SFD is detected).
This value is updated when a good PHR is detected (when the RXPHD status bit is set).
The channel accumulation sometimes includes the SFD symbols, all except the last two. Signal
power calculations using RXPACC for the number of symbols sometimes need to be adjusted
for the SFD symbols accumulated. See section 4.7 for calculations using RXPACC.
The RXPACC counter will saturate when preamble is found by the receiver and the CIRE will
stop accumulating symbols. A debug symbol counter which does not saturate is given in
count needs to be adjusted if the two counts are equal. If they are not equal, then RXPACC has
saturated before SFD accumulation and therefore the RXPACC value need not be adjusted
before use in signal power calculations.
To adjust the RXPACC count for SFD when RXPACC is equal to
, subtract the
number of SFD symbols from the count. Because the SFD sequences contain positive symbols
(normal preamble symbols) and negative symbols (symbols which are inverted versions of
preamble symbols) which have been added into the channel estimate, add the number of
positive symbols and subtract the number of negative symbols in the SFD sequence from the
RXPACC count. The last two symbols in the SFD sequence are always ignored in the channel
estimate, so these two symbols should not be counted when making adjustments to RXPACC.
See Table 18 below for some examples of how to adjust RXPACC when RXPACC and
Note that the shorter the preamble length, the more impact the SFD correction to RXPACC will
have on signal power calculations.
