PXI-5661

[Dannn]

Hi

i want to know whether the downconverter(5600) of 5661 can be used separately with another digitizer such as 5122e?

are the two modules i.e 5600 and 5142 completely detachable and if that is so than do i need to get separate drivers for both?

secondly, as i understand it, 5600 has 20 MHz bandwidth but what i need is a down converter that can be used for data streaming 50 MHz+ BW data using 5122e. how to go about this problem?

thirdly, for data streaming RF data to RAID0 or PXI-controller HDD, do i need to use a RF switch (because 2593 is recommended by you) and do i need AWG such as 5421?

what exactly is the utility of RF switch here?

dannn

[Robert_F]

Hello Dannn,

The 5661, which is a combination of the 5600 and 5142 will use the NI-RFSA driver.  If the 5600 is used alone, then it will use the NI-Turner driver.  The 5142 will use the NI-SCOPE driver if it is used alone.  If you want to use them together, then you have to go into MAX and associate the 5600 with the 5142. 

The PXIe-5122 (which uses the NI-SCOPE driver) cannot be associated with the 5600 so that the NI-RFSA driver can be used.  However, they can be used in the same application.  You are just loosing the tight synchronization that you get with the NI-RFSA driver. 

The 5600 has a fixed BW of 20MHz and cannot be adjusted.  The NI-RFSA driver can span the 50MHz+the BW with no problems.  The only way that the 5600 can provide real-time continuous data is if the BW is set to 20MHz. 

The RF Switches are only required if you need more than one signal to be connected to your 5661.  The 5421 is not needed to stream data to a RAID Array.  However if you want to replay and stream the data from your RAID Array, then I would recommend the 5672, which uses the NI-RFSG driver.

[Dannn]

Hi

Thanx for the reply. now i want to ask another thing. can i use 5661 alongwith controller such as 8106,8130 and modulation toolkit for real-time demod of qpsk/qam?

danyal

[Matt_A]

Hello danyal,

The Modulation Toolkit provides an example program called MT niRFSA QAM Continuous Demod.vi which "demonstrates continuous acquisition and online demodulation of a QAM signal." For more information about this example, I would recommend you examine this tutorial which describes continuous demodulation of a QAM signal.

I have run this example on a PXI-1006 chassis with a PXI-8196 controller and a PXI-5661 Vector Signal Analyzer and have been able to acquire and demodulate live RF data. Given the improved performance of the PXI-8106 and PXI-8130, this operation should be no problem on those controllers. However, if you are asking if you can perform this operation on the PXI-8106 RT or PXI-8130 RT PXI controllers with LabVIEW Real-Time, then I would direct you to the NI-RFSA driver download page here. There you will notice that the NI-RFSA driver does not currently offer support for real-time operating systems. Therefore, you cannot run the PXI-5661 in a PXI system running LabVIEW Real-Time.

[Dannn]

hi

again, for a trasceiver, all the processing including source,channel coding such as CELP and viterbi etc will have to be done on the controller i.e 8130 and channel(s) passed out via USB/Ethernet. so given it is a transceiver, is all the processing (REAL TIME) possible on a windows based controller or do we have to shift to RTOS based controller? i understand the point about NI-RFSA not currently supporting labview RT but then how to do it?

thanx in advance

[Raajit_Lall]

Dannn,

The controller will be able to handle all the processing that you mentioned in your post (using the toolkits).  Since there is a 20Mhz bandwidth limitation and a maximum sampling rate that you can use on the digitizer as well, that makes sure that the data can be passes over the PCI bus to the controller.  Once the data is in the controller, its is processed in software.  The only processing that is done in hardware is shown in the diagram below.  As you can see, the incoming signal is broken into I and Q data on the OSP (On Board Signal Processing) unit on the digitizer. 



This is very efficient because we can now transfer all that data through the PCI bus to the controller.  This OSP is available only on the 5142 digitizer, which is what is used with the 5600 for our RFSA driver.

You mentioned transfering the data through ethernet.  I am a little confused as to why you are planning to use ethernet/USB?

Regards,


Message Edited by Raajit L on 03-14-2008 10:55 AM

[Dannn]

Hi

the ethernet may be used to connect to a workstation/laptop to the controller to receive log files/control info or even processed (by controller) data etc and on the transmit side, pass on the data to controller for error coding, modulation etc

maybe i've confused you, you see going from downconverter to digitizer/ddc to controller, we have bandlimited data max upto 20 MHz, that is clear. now this process is all real-time, no problem!!!

in the controller, we have the toolkits for demod, but probably none for viterbi or CELP, so i will have to write it myself or integrate with a custom module, right....

my question actually was that if the baseband processing functions such as viterbi and CELP are attempted in real-time on a windows platform of 8130e, would it be possible? or do i need a RTOS on 8130 for doing these? the data rate may be upto 23.394  Mbps.

you see even if i can get real time data upto controller, it doesnt solve the entire problem for me because i need to process the data received by controller in real-time as well to get to data/voice level and vice-versa.

thanx for taking the time

danyal

[Raajit_Lall]

Thank you for the clarification Danyal.  You could make the Viterbi and CELP calculations on a Windows machine.  I did find a few places where we already have some example code for the viterbi if you are interested.  Here is a forum post that talks about viterbi and here and here are some example programs from our website. 

The answer to your question about whether doing these algorithms in real time is, yes.  You could implement viterbi and CELP both in Windows and on an RT (Real Time) Operating System.  I would recommend using the RTOS and not a Windows machine for your real time measurements.  Windows will not be as deterministic as a real time machine would be for you calculations.  You can just use LabVIEW real time to program your algorithm.  I could not find any examples that would achieve this for your.  However, the programming in real time is very similar, so I think you could use the above code to make your programs in real time as well.  Just to clarify, programming on an RTOS instead of a Windows machine will not make it faster, only more deterministic.  Also, the only thing that will be running on your RT machine will be the programs you wrote, so there will be no "lag" or interference caused by other programs running in the background (on a Windows machine).

To summarize, it depends on what kind of determinism, you are looking for.  If you are looking to process the data as soon as possible, you might want to look at some kind of FPGA solution, but if you are just looking for some kind of determinism, you might be better off with a real time operating system on your 8130. 

Hope this helps.

Regards,

[Dannn]

Hi,

The point about determinism is clear. Thanx for the insight, now comes the problem of NI-RFSA driver that is not currently offered for RT, that means what? (pl refer reply 3 to my post by Matt) how to go about it if i choose RT?  the reason i am not considering FPGA at the moment is because i need a flexible solution, easily upgradabale etc.

danyal

[Matt_A]

Hello danyal,

With the introduction of NI-RFSA 2.0.7, we now offer support for the NI PXI-5661 in the LabVIEW 8.5 Real-Time Module. This update was released in December of last year, and I apologize for not updating this post with the pertinent information. However, the Modulation Toolkit does not offer support for any real-time operating system, so any demodulation or decoding algorithms would have to be written from scratch in LabVIEW.