[USRP-users] Problem using RX1 and RX2 of TVRX2 at different time

Mike Jameson mike.jameson at ettus.com
Mon Sep 23 06:56:59 EDT 2013


Hi Cheng,

Please note that each channel of the TVRX2 can receive at a maximum
bandwidth of 10MHz so sampling with a sampling rate of more than 12.5e6
(100e6/8) per antenna will not increase the receive bandwidth as expected:

http://files.ettus.com/uhd_docs/manual/html/dboards.html#tvrx2

You can only use one USRP object per device and therefore for the TVRX2,
switching between an RX1 only and RX2 only stream requires stopping the
flowgraph in the following sequence:

tb.stop()
tb.wait()

set_subdev_spec("A:RX2", 0)

tb.start()


Regards,

Mike

--
Mike Jameson M0MIK BSc MIET
Ettus Research Technical Support
Email: support at ettus.com
Web: http://www.ettus.com <http://www.ettus.com>


On Mon, Sep 23, 2013 at 11:03 AM, Cheng Chi <ch0004hi at e.ntu.edu.sg> wrote:

> Hi all,
>
> Anyone knows how to record data from both RX1 and RX2 of TVRX2 but not at
> the same time? We are using USRP N210.
>
> Here is our problem scenario in detail:
>
> We specify subdevice using set_rx_subdev_spec("A:RX1 A:RX2") and adapt the
> code from examples/rx_multi_samples.cpp. It works well at sampling rate of
> 10Msps. But when we increase the sampling rate to 25Msps, we have an
> overflow indication. We guess it's because we let the two channels stream
> at the same time, which is too much for the USRP or the write medium.
>
> However, all we need is sampling at one channel at a time, so we try to
> sample and record data at RX1 for some time period T and put RX1 into idle
> mode, and then sample and record data at RX2. But we don't know how to set
> the subdevice correctly.
>
> We create two usrp objects and do the channel mapping in the following
> way, but it seems that we are only sampling data from RX2.
> {{{
> rx1_usrp -> set_rx_subdev_spec("A:RX1")
> rx2_usrp -> set_rx_subdev_spec("A:RX2")
> }}}
>
> I really appreciate any help you can provide.
>
> Best regards,
> Cheng Chi
>
> _______________________________________________
> 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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