USRP property

[Ktim]

Hi,

I am working on generating bpsk/qpsk scan signal ranging from 174 Mhz to 180 MHz carrier frequency. I generated an array of frequencies and feeding it to the USRP carrier frequency property. I am writing the frequencies like 174 MHz, 174.25 Mhz.....untill 180 Mhz but when I read from the carrier frequency property it shows me -29 MHZ (negative values for frequency). Can anyone tell what is wrong with my USRP property or what needs to be added?

I am using USRP N210 and LABVIEW 2015.

Thanks,

Ktim

[Stop_Luke_and_Listen]

Hi Ktim,

What daughterboards are you using with your USRP N210?

[Ktim]

Hi Luke,

I am using BasicTX Daughterboard (E7R02Y5TB) and Basic Rx (1-250 MHz). I don't know why but when I enter 174 Mhz as frequency input, I get -26 as the coerced actual frequency. 

And to add something, is niUSRP open Tx session . vi compatible with N210? I guess this might be the cause of error as it may not have been able to recognize N210 through IP address.

Thanks,

Ktim

[Stop_Luke_and_Listen]

Hi Ktim,

The reason it's not working correctly could potentially be because the NI-USRP driver does not directly support the Basic TX and Basic RX daughterboards (http://www.ni.com/pdf/manuals/374760k.html).  The N210 is supported by the driver, but only with other daughterboards such as UBX and WBX.

[Ktim]

Hi Luke,

Do you think I should change my daughter-board? Or is there any other step that I can follow to make it compatible with NI-USRP?

Thanks,

Kripa 

[alynch]

The N210 has a sample rate of 100MHz, so the highest frequency that it can directly sample on the Basic Rx is 50MHz. For frequencies above that, it will only receive an alias of the signal below that frequency. When you request a frequency above 50MHz, it will tune to the frequency of the alias and read back as a value from -50MHz to 50MHz. You should be able to receive the signal at 174MHz properly with the Basic Rx, but you may need additional filtering since signals at 26MHz, 74MHz, 126MHz, 174MHz, etc. will all appear at the same frequency.

[Ktim]

Hi,

Thank you for the response. If I change my daughter board to WBX (50-2200 MHz), will it then be able to directly sample 174 MHz and above?

Thanks,

Ktim

[alynch]

Yes, a WBX daughterboard can tune directly to 174 MHz.

[Ktim]

Thank you.