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
Kind Regards,
John
From: Wahhab Albazrqaoe
Sent: Saturday, December 30, 2017 4:39 AM
To: Kyeong Su Shin
Cc: John Shields ; [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]> 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
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
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