Hi Carlo,
To answer your question directly, you cannot stream the full 20 MHz
bandwidth of the analyzer. To cpture the full bandwidth, the PXI-5620
digitizer component of the PXI-5660 analyzer will run at 64 MSPS,
giving you a data rate of 128 MB/sec. This is too close to the
theoretical limit of the PCI bus of 133 MB/sec to sustain.
The PXI-5620 digitizer does have an onboard Digital Downconverter (DDC)
with a bandwidth of 1.25 MHz. What this means is that for requested
spans of <=1.25 MHz, the data rate is greatly reduced by the DDC,
allowing streaming. So, you can stream with the PXI-5660 up to a
bandwidth of 1.25 MHz.
The PXI-5661 analyzer sounds more applicable to what you are looking
for. It is the same PXI-5600 downconverter with a more powerful
digitizer, the PXI-5142. The PXI-5142 hqas a Digital Downconverter with
a bandwidth of 40 MHz, so acquiring the full 20 MHz output of the
PXI-5600 can be done with the DDC on. Basically with the PXI-5661, the
digitizer's DDC is always on. This means reduced data rates in all
cases.
We have created streaming applications that stream the full 20
MHz BW to RAID0 arrays of hard drives to allow post-processing. This is the use case of streaming data to disk with minimal inline processing. Streaming to host memory (RAM) and doing inline processing creates many more variables and will require faster controllers, etc...
Regards,
Andy Hinde
National Instruments
