Thank you Jeff..
Are these filters in software? Or fpga? Is there any function that we
play with to get aliasing? i.e. how to disable such filters?
Thank you
Wahhab
The B2XX bandwidth can be adjusted, but that is in addition to other
filters designed to remove aliases based on the sample rate.
On Dec 29, 2017 11:57 AM, "Wahhab Albazrqaoe" <[email protected]
<mailto:[email protected]>> wrote:
Hi John,
My question is about USRP B210, can we use it to set RF bw as 50MHz
and then sample using 2MHz sampling rate?
Thanks
Wahhab
On Dec 29, 2017 11:54 AM, "John Shields" <[email protected]
<mailto:[email protected]>> wrote:
Hi Wahhab,
As Kyeong had already pointed out, in this configuration, the bw
limiting factor is the daughtercard. For the SBX the bandwidth
is 40 MHz. There are other Ettus products covering the same
frequency range which have wider bandwidth (80,120,160 MHz) but
they seem to only plug into the X-series of products.
https://www.ettus.com/product/category/Daughterboards
<https://www.ettus.com/product/category/Daughterboards>
Kind Regards,
John
*From:* Wahhab Albazrqaoe <mailto:[email protected]>
*Sent:* Saturday, December 30, 2017 4:39 AM
*To:* Kyeong Su Shin <mailto:[email protected]>
*Cc:* John Shields <mailto:[email protected]> ;
[email protected] <mailto:[email protected]>
*Subject:* Re: [USRP-users] Enable aliasing using USRP
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]
<mailto:[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]
<mailto:[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]
<mailto:[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
<https://en.wikipedia.org/wiki/Nyquist_frequency>
Kind Regards,
John
*From:* Wahhab Albazrqaoe via USRP-users
<mailto:[email protected]>
*Sent:* Friday, December 29, 2017 3:04 PM
*To:* [email protected]
<mailto:[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
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