Dear Kyeong, Thank you for the reply. How about using USRP B210, do you think we can get aliasing by setting the RF bw=50MHz and sample at 2MHz?
Thank you. Wahhab On Dec 29, 2017 12:19 AM, "Kyeong Su Shin" <[email protected]> wrote: > Hello Wahhab, > > If I recall correctly, you can *not* change the bandwidth of SBX (always > 40MHz), and the sampling rate of the USRP2 (always 100MS/s). What you are > actually setting by setting --rate 2e6 is the decimation ratio. The signals > will be always sampled at 100MS/s, and then decimated by the decimator > within the FPGA. > > It is still possible to cause aliasing - one way is to just sample at a > fast sampling rate and then decimate by yourself. An other way would be > tinkering the digital filters used by the decimator, but I am not sure if > there are good APIs to do that. I am pretty sure that rx_samples_to_file is > not suitable for the task, though (correct me if I am wrong). That is just > an example program. > > Regards, > Kyeong Su Shin > > On Thu, Dec 28, 2017 at 6:29 PM, Wahhab Albazrqaoe via USRP-users < > [email protected]> wrote: > >> Hi John, >> Thank you for your reply. >> We would like to create aliasing. This means that we should set ADC to >> sample at speed less than Nyquist rate. >> In our setting, we target RF front end to be 50MHz and ADC speed is 2MHz. >> The question is how to do it? We use some commands (as shown in my >> previous email) but seems not working as expected, i.e. RF front end >> bandwidth is still 2MHz. >> >> Best, >> >> On Thu, Dec 28, 2017 at 9:24 PM, John Shields <[email protected]> >> wrote: >> >>> Hi Wahhab, >>> This is a fairly basic issue – the ‘bandwidth’ (if >>> that is really what you are really meaning) is related to the sample_rate >>> by The Nyquist Frequency >>> >>> https://en.wikipedia.org/wiki/ >>> Nyquist_frequency >>> >>> Kind Regards, >>> >>> John >>> >>> *From:* Wahhab Albazrqaoe via USRP-users <[email protected]> >>> *Sent:* Friday, December 29, 2017 3:04 PM >>> *To:* [email protected] >>> *Subject:* [USRP-users] Enable aliasing using USRP >>> >>> Dear All, >>> I have question about how to create aliasing using USRP. >>> Basically, I have USRP2 with SBX (with recent installations of GnuRadio >>> and UHD). >>> I would like to set the bandwidth of the RF front end to 50 MHz, and use >>> 2MHz of sampling rate (ADC speed). >>> I am using the following command: >>> sudo ./rx_samples_to_file --args addr=192.168.10.2 >>> master_clock_rate=50e6 --freq=2460e6 --bw=50e6 --rate 2e6 --gain=50 >>> --wirefmt sc8 --nsamps 0 >>> >>> >>> >>> Problem: it seems to me that the system (GnuRadio/USRP) observes only >>> 2MHz of RF front end bandwdith. How do I know this? Ans: I compare such >>> settings with the following settings: >>> sudo ./rx_samples_to_file --args addr=192.168.10.2 >>> master_clock_rate=50e6 --freq=2460e6 --bw=50e6 --rate 50e6 --gain=50 >>> --wirefmt sc8 --nsamps 0 >>> >>> The later setting seems to be actual 50 MHz of Rf front end. >>> >>> Any comments and advices on how to create aliasing using USRP are >>> appreciate. >>> >>> Best, >>> Wahhab >>> >>> >>> >>> ------------------------------ >>> _______________________________________________ >>> USRP-users mailing list >>> [email protected] >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >>> >>> >>> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> >>> Virus-free. >>> www.avast.com >>> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> >>> <#m_3776995265834237337_m_-1409356437401843074_m_5211752623429318912_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> >>> >> >> >> _______________________________________________ >> USRP-users mailing list >> [email protected] >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >> >
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