Info about NI USRP-2901

[jlgomez1989]

Hi guys, I'm curious about the capabilities of the NI USRP 2901. My goal is to transmit an OFDM signal of 56MHz in RF using 61.44 MS/s (which is maximum bandwidth and sampling rate that the datasheet says it can handle).

However, I check similar equipment  (e.g. B-205 mini) in which its mentioned that they have problems with the clock that connects to the FPGA and it can compromise the performance of the equipment. Does this equipment have similar problems? I would like to know this before purchasing the equipment.

I really appreciate any help/information you can give me.

Cheers

Jorge Gomez

[paigec]

Hi Jorge, 

What are some of the key clocking and synchronization requirements for your application? And how do you intend to program the clock in FPGA? There are different synchronization methods available on different USRP devices, as was discussed on this page on the forums. Beyond this, what are some of the performance needs you have for this project that informed this concern? By getting more specific context on what you're aiming to do, we can better help identify the right hardware. 

Otherwise, the sales engineering team at National Instruments can have a conversation with you about the overall application, additional requirements, and other considerations you may have to help you in the selection process, which is recommended for new projects. 

Thank you and have a great rest of your day! 

Cheers, 

Paige

[jlgomez1989]

Hi, thank you for your reply. My goal is to put the NI USRP 2901 in a drone and set it to transmit an OFDM signal of 56 MHz bandwidth in RF @ 3.5 GHz continuously and receive it using a NI PXI-5162 connected to a switch with multiple antennas for doing channel sounding. A key factor for this project is to have both Tx and Rx synchronized and for this purpose, we use the REF in and PPS in signal for the NI-2901 and the PXIe-5162, we have a GPSDO for the PXIe5162 and we have purchased a GPSDO for the USRP 2901. Even though the GPSDO we have is good if the PLL and/or the clock circuit in the USRP is not good the synchronization will be compromised in our system.

The frequency accuracy I'm looking for is 2 ppm at most (maybe 3 ppm) when locked to an external clock signal the accuracy would be less than 30 ppb, stable in temperature and a transmit power of +20 dBm.

Cheers

Jorge Gomez

[paigec]

Hi Jorge, 

What's the GPSDO you are hoping to use with the USRP 2901 (ex. part number)? The reason I ask this is that there is a limitation related to the GPSDOs for this device, explained in this forum. 

The USRP-293X series has an integrated GPS-disciplined reference clock, and the 292X series requires an externally sourced clock. More info on the GPSDO support can be found in the Getting Started Guides for the USRP-293x and USRP-292x series. What review have you done of these devices, and would you be looking for a more inherent ability for GPS-disciplining? 

Cheers, 

paigec

[jlgomez1989]

Hi, I'm looking in some options from Jackson Labs, specifically the Firefly 1A http://www.jackson-labs.com/index.php/products/firefly_1a.

I also checked other options for USRP but one limitation we have for our project is the weight because we're going to put the USRP in a Drone for transmitting our sounding signal. We also looked for 2 options from Ettus Software: the TCXO and the OCXO. 

https://www.ettus.com/all-products/GPSDO-TCXO-MODULE/

https://www.ettus.com/all-products/GPSDO-MINI/

Cheers

Jorge Gomez