Appendix D _________________________________________________ RVP900 Developer's Notes
VAISALA______________________________________________________________________ 403
command arrives, along with the two input words, which are expected by
that opcode. No output words are generated by SNOISE. The GPARM
opcode is received and the 64 output words that it produces are displayed.
Watching the opcode-level activity of the signal processor is helpful when
debugging both custom driver code and custom opcode handlers that you
might write for the RVP8.
D.3.2 Showing Live Acquired Pulse Info:
-showAQ
The (I,Q) data that are computed by the FIR filters on the RVP8/Rx PCI
card are transferred to CPU memory by way of Direct Memory Access
(DMA) bus cycles that are initiated by the RVP8/Main threads. This is an
implementation detail that developer's can ignore, except to be aware that
the radar data always arrive in discrete "chunks" and that the TimeSeries
API is updated accordingly. The following printout shows the (I,Q) bus
activity for a Dual-Polarization (dual RVP8/Rx cards) system, when the
-showAQ flag is included on the RVP8 startup command line.
AQ:193 pulses(1:1B96 – 1:1C57) 32038 words(8:2762F –
8:2F355) 157ms
AQ:192 pulses(1:1B9B – 1:1C5B) 31872 words(8:27B0A –
8:2F78A) 3ms
AQ:191 pulses(1:1C57 – 1:1D16) 31706 words(8:2F355 –
8:36F2F) 157ms
AQ:192 pulses(1:1C5B – 1:1D1B) 31872 words(8:2F78A –
8:3740A) 4ms
We see 193 pulses of packed 32-bit (I,Q) data words being transferred
from the first Rx card, followed 3 ms later by a similar transfer from the
second Rx card. Each block of data is moved directly into the virtual
address space of the RVP8/Main, without requiring any cycles from the
CPU itself. A DMA-Done interrupt causes the IQ-Data thread to wakeup
and unpack that card data into FLT4 values, which are written to the
TimeSeries API.
Do not worry too much about the other numbers that are printed from
-showAQ. The flag's main use is to show how chunks of timeseries data are
being made available to the RVP8 processing threads. If you are curious
about the timing details, this is a simple way to take a look.
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