Adquisición de datos con una USRP conectada mediante un PXI y LabView

[AnAlH]

Buenas,

Estoy trabajando con un PXIe-1095 al que se le conecta una Ettus USRP X310 configurada con 2 TwinRx mediante el modulo PXIe-8374. Se emplea la version LabView 2021 SPI para realizar una adquisición de datos. Al trabajar con un sample rate inferior a 50MSps no hay problema y no se producen overflows, sin embargo a partir de 50MSps se obtienen overflows. Estoy usando una configuracion consumidor-productor.

Entiendo que el PXI debería ser capaz de manejar esta tasa de transferencia de datos ya que al comprarlo nos aseguraron que podía llegar a los 100MSps sin problema, entonces no sé porque está fallando a partir de los 50MSps. ¿Alguna idea de que puede estar pasando?

Por otro lado, LabView no es capaz de detectar las USRP correctamente, hay que introducir de forma manual la IP, ¿esta puede ser una posible causa? Si ese es el caso, ¿porque con rates altos falla y con bajos no?

Muchas gracias de antemano.

Un saludo,

Anabel

[mikiofuku]

Hi
You can change the number of samples. for examples 10k, 8192, 256K....Try it.
and you can change DMA buffer size if you use LabVIEW FPGA. Target to Host DMA buffer size is 1024 as default. However the default value causes overflow at high sampling rates.
I suggest using 8k samples for Target to Host DMA buffer size.

[AnAlH]

Thank you very much for your reply.

I have tried increasing the number of samples as you indicated. I have also read that making it a multiplo of 1020 is advisable. But I still have the same problem. Sometimes it takes a little longer to get overflow, but it always appears.

I'm quite new to this and I 'm a bit lost, I don't think I use the FPGA.

[mikiofuku]

Hi,

USRP X310 can sent up to 200Msps on PCI Express bus.
If you use 4ch on TwinRx then transfer rate reaches it limit.
4ch x 50Msps = 200Msps.

Thank you

[AnAlH]

Hi, 

Does this mean that an overflow is inevitable? I thought the PXI was capable of handling data internally so that it could handle data rates higher than 200MSps.

What can I do to get higher sample rates, is there a specific configuration or structure I can implement?

I have tried a producer-consumer configuration, but I keep getting overflows.

Thank you very much for your help.

[mikiofuku]

Hi, 

You can use dual 10GbE ethernet connection instead of PXIe connection. max 625MS/s.

Transfer rate per one 10GbE channel (theoritical)
10Gb/s = 1.25GB/s = 312.5MS/s x 2ch = 625MS/s

Please see "niUSRP EX Rx Dual Ethernet Connection.vi" in NI-USRP Example folder, you can found it in Windows Start Menu.

Thank you.