USER’S MANUAL__________________________________________________________________
330 _________________________________________________________________ M211322EN-D
7.28 Set User IQ Bits (UIQBITS)
Load user-specified bits that will be included with the pulse headers in the
RVP900 TimeSeries API data stream. The permanent Set/Clr bits are
updated in the signal processor and retain their value from the last time
they were defined. These bits are then repeated into all pulse headers. The
ONCE bits, however, are transitory and will appear in only one pulse
header each time they are set.
A FIFO history of the permanent bits is maintained so that the bits can be
associated with the data being acquired right now as the UIQBITS opcode
is executed. Each 16-bit command arg specifies bits to Set/Clr in
successive bytes of the structure. This allows user code to safely change
some bits without affecting others.
The user bits from separate calls will never be collapsed into a single pulse
header, even if the header and bit times indicate that they could. This
means that each UIQBITS opcode will always result in at least one pulse
header being tagged with exactly those data. This is generally what you
want, since no other exact outcome could be guaranteed based on time-of-
arrival alone.
PhSeq=2 Selects a User Defined sequence. If no XARGS have been
supplied, then the RVP900 outputs the default idle phase
that is defined in Mz. If XARGS are supplied, then they
are interpreted as a sequence of 16-bit binary angles. The
RVP900 will make the best match between each desired
angle and the closest realizable angle that the phase
modulation hardware can produce. The maximum length
of the sequence is 1024 pulses.
PhSeq=3
Selects the SZ(8/64) sequence. This is a systematic code
4
,
which does a nice job separating and recovering first and
second trip echoes in "Random Phase" mode. It will
usually perform better than a truly random transmit
sequence, especially when the processing interval is fairly
short (as little as 32-pulses). With no XARGS, the RVP900
automatically generates the phase sequence using the
closest realizable angles that the phase modulation
hardware can produce. This is the recommended way to
invoke SZ(8/64) coding. However, you may also supply
your own 32-pulse angle sequence.
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