Using Packet-based Digital Link Example with NI-RFSG and NI-FGEN

[YYYs]

Hi,

I am trying to get the Packet-based Digital Link Example (https://decibel.ni.com/content/docs/DOC-18801) running on a RF Upconverter PXI-5610 and a AWG PXIe-5442 using the NI-RFSG and NI-FGEN drivers. The Upconverter and AWG should run as the transmitter while a USRP run as the receiver.

After linking both cards in MAX and replacing the niUSRP functions with the niRFSG functions inisde the USRP Packet Transmitter.vi I received the following error message:

code -1074118136

niRFSG Write Arb Waveform (Complex DBL).vi<ERR> The AWG reported the following error: 

You cannot write data outside the boundaries of your waveform. Make sure you are not trying to write more data than your waveform can accomoate and that your write location and write offset are set correctly.

Status Code: -200311

I was able to solve this error by inserting the niRFSG Clear All Arb Waveforms.vi inside the transmitting loop. Now no error message appears anymore, but I can't receive any packets with the USRP Packet Receiver.vi. I also noticed the status LED "ACTIVE" at the front of the card is not on when the VI is running. When I am using the Soft Front Panel the LED turns on.

Thanks in advance!

[Sarah_Y]

Hey YYY,

I took a look at your code that uses NI-RFSG with your NI-5672 (5610+5442).  The original USRP transmit code had to be architected using queues to stream the new samples to the USRP to write each time because there is no onboard memory on the USRP.  Since you are using an arb with onboard memory, you don't necessarily have to do this.  If you want to keep the queues in the code, you should set up the RFSG portion to look like a streaming application.  There is an RFSG example called RFSG Arbitrary Waveform Streaming.vi that is a good place to start to see how the driver is set up.  It is a more complex driver than the USRP and has a few extra steps.  For example, you need to have a call to niRFSG Initialize.vi, regardless of whether you are doing streaming or not.  If you choose to write all of the data to your arb before sending it out, RFSG Arbitrary Waveform Generation.vi is a good place to start.

I'm not entirely sure why your USRP isn't working with the 5672.  Can you provide more details?  Are you getting an error from the USRP?  How do you have the USRP connected to the VSG?  Make sure you have an attenuator in the path if you aren't using 2 antennas, it is easy to damage the USRP by putting in too much power.  You are using the RFSG soft front panel 1.9, correct?  I have used a USRP with RFSG on numerous occasions and not had an issue, so the more details you can provide the easier it will be to troubleshoot.

I don't have the equipment to set up your code and test it out unfortunately.  I was going to recommend you post to the RF measurement devices forum, but it looks like you have already done that.  Hopefully this information will at least be a starting point to get your system running.

[wicak]

For the packet based digital link example? If we want to add CRC, how we're gonna do it? I already looked at CRC source code on the internet, and basically the vi accepts input byte string. As I know, the data for modulation toolkit it bit array.