[USRP-users] using uhd_fft with usrp N210

Kyeong Su Shin ksshin at uw.edu
Tue Nov 28 09:54:20 EST 2017


Dear Sung Bok,Lee:

Forgot to mention - so, in short, all it can do is 'digitally' shifting
signals if you use BasicRX/BasicTX daughterboards. The analog frontends do
not filter any signals (although the daughterboards themselves act as poor
low pass filters with bandwidth of 250MHz), nor mix them down to any
frequencies. The 'tuning' that I mentioned in the second paragraph of the
previous e-mail is 'digitally' shifting down the signal (done by the USRP
motherboard's FPGA).

Regards,
Kyeong Su Shin

On Tue, Nov 28, 2017 at 6:41 AM, Kyeong Su Shin <ksshin at uw.edu> wrote:

> 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
>>
>>
>
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