[USRP-users] using uhd_fft with usrp N210

Kyeong Su Shin ksshin at uw.edu
Tue Nov 28 09:41:08 EST 2017


Dear Sung Bok,Lee:

You are using BasicRX/BasicTX daughterboards. These daughterboards do not
have any mixers, so they cannot 'tune' to any frequencies and you have to
supply your own RF frontends to get reasonable performances.  All these
daughterboards do for you is just buffering the ADC/DAC and then providing
SMA connectors for the connection. You have to use different daughterboards
if you do not want to come up with your own frontends and yet want to get
good signals.

If you use BasicRX/BasicTX and ask your USRP to tune to frequency x, it
will actually tune to an aliased frequency. USRP N200/N210 have native
sampling rate of 100MS/s. DAC sampling rate is rated to 400MS/s, but the
master clock is still at 100MS/s - it is just that the DAC is internally
interpolating the data you are inputting by 4x. So, if you ask it to tune
to 100MHz, it will tune to 0MHz instead - where the 100MHz signals will
alias onto.

Regards,
Kyeong Su Shin

On Mon, Nov 27, 2017 at 8:51 PM, 이성복 via USRP-users <
usrp-users at lists.ettus.com> wrote:

> Hi
>
> I have 2Questions
>
> I was install Linus Ubuntu 16.04 LTS,
>
> sudo apt-get update
>
> sudo apt-get upgrade
>
> and install uhd and gnuradio (https://kb.ettus.com/
> Building_and_Installing_the_USRP_Open-Source_Toolchain_(
> UHD_and_GNU_Radio)_on_Linux)
>
> and  uhd_images_downloader
>
> uhd_image_loader --args="type=usrp2,addr=192.168.10.2"
>
> benchmark_rate --tx 10e6 --rx 10e6
>
> and test it  tx_waveforms --rate 10e6 --freq 100e6
>
> then
>
> Using Device: Single USRP:
>   Device: USRP2 / N-Series Device
>   Mboard 0: N210r4
>   RX Channel: 0
>     RX DSP: 0
>     RX Dboard: A
>     RX Subdev: BasicRX (AB)
>   TX Channel: 0
>     TX DSP: 0
>     TX Dboard: A
>     TX Subdev: BasicTX (AB)
>
>
>
> Setting TX Rate: 10.000000 Msps...
> Actual TX Rate: 10.000000 Msps...
>
> Setting TX Freq: 100.000000 MHz...
> Actual TX Freq: 0.000000 MHz...
>
>
>
> 1. Why Actual TX Freq is 0?? And when I run uhd_fft , I can see only 0hz
> signal. But I set center freq 100Mhz.
>
> 2.I try to example (uhd_tx_dpsk of gr-uhd) and run in gnuradio-companion
> and see flowgraph, but I measured signal using spectrum analyzer I can't
> see signal.
>
>   I put subdev A:AB in USRP SINK block and antenna is TX/RX. What should i
> do for transmit dpsk signal?
>
>
>
>
>
> Windows 10용 메일 <https://go.microsoft.com/fwlink/?LinkId=550986>에서 보냄
>
>
>
> _______________________________________________
> USRP-users mailing list
> USRP-users at lists.ettus.com
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/attachments/20171128/491a8885/attachment-0002.html>


More information about the USRP-users mailing list