It seems working now. Two channels can receive the signal sent on the their
own target frequencies.
Below is my code.
self.uhd_usrp_source_0 = uhd.usrp_source(
device_addr="",
stream_args=uhd.stream_args(
cpu_format="fc32",
channels=range(2),
),
)
#self.uhd_usrp_source_0.set_clock_rate(918000000, uhd.ALL_MBOARDS)
* tr1 = uhd.tune_request(908e6, rf_freq=918e6,
rf_freq_policy=uhd.tune_request.POLICY_MANUAL);
tr2 = uhd.tune_request(928e6, rf_freq=918e6,
rf_freq_policy=uhd.tune_request.POLICY_MANUAL);*
self.uhd_usrp_source_0.set_subdev_spec("A:0 A:0", 0)
self.uhd_usrp_source_0.set_samp_rate(1024000)
#self.uhd_usrp_source_0.set_center_freq(908000000, 0)
*self.uhd_usrp_source_0.set_center_freq(tr1, 0)*
self.uhd_usrp_source_0.set_gain(0, 0)
self.uhd_usrp_source_0.set_antenna("RX2", 0)
#self.uhd_usrp_source_0.set_center_freq(928000000, 1)
*self.uhd_usrp_source_0.set_center_freq(tr2, 1)*
self.uhd_usrp_source_0.set_gain(0, 1)
self.uhd_usrp_source_0.set_antenna("RX2", 1)
But my code is still different with one of your post here
http://lists.gnu.org/archive/html/discuss-gnuradio/2011-09/msg00309.html.
I think the dsp_freq is used for other purpose, right?
On Mon, May 21, 2012 at 9:27 PM, Josh Blum <j...@ettus.com> wrote:
>
>
> On 05/21/2012 06:57 PM, Alex Zhang wrote:
> > A little confused.
> >
> > I am using the gnuradio-companion to configure the uhd.usrp_resource.
> > What is the difference between the rf_freq and the center_freq? How the
>
> Basically, you have two down conversion chains that share a common RF
> frontend, but independent DSP chains in the FPGA.
>
> See: http://files.ettus.com/uhd_docs/manual/html/general.html#tuning-notes
>
> Also see:
>
> http://files.ettus.com/uhd_docs/doxygen/html/structuhd_1_1tune__request__t.html
>
> > tune_request (is it a UHD method?) can be reflected in the
> > gnuradio-companion setting?
> >
>
> Just copy and paste the code I sent you into the center frequency
> parameter.
>
> -josh
>
> > On Mon, May 21, 2012 at 6:29 PM, Josh Blum <j...@ettus.com> wrote:
> >
> >>
> >>
> >> On 05/21/2012 04:12 PM, Alex Zhang wrote:
> >>> Thanks!
> >>>
> >>> I am trying to set up two channels on RX2 as Nick said. And the subdev
> is
> >>> set as "A:0 A:0". Please see the attachement for the GRC flow graph.
> >>>
> >>> But my problem is that it seems that both the channels can not receive
> >> the
> >>> expected signal(I am using an OFDM transmitter for test).
> >>> The single channel with frequency of 908M or 928M works well as I can
> see
> >>> the OFDM spectrum from the observing FFT plot window.
> >>>
> >>>
> >>
> >> What did you enter for ch0 and ch1 center frequency? I recommend this:
> >>
> >> uhd.tune_request(908e6, rf_freq=918e6,
> >> rf_freq_policy=uhd.tune_request.POLICY_MANUAL)
> >>
> >> uhd.tune_request(928e6, rf_freq=918e6,
> >> rf_freq_policy=uhd.tune_request.POLICY_MANUAL)
> >>
> >> Its important the RF frequency be the same for each channel, otherwise,
> >> the second tune for channel1 will override the tuning for channel0.
> >>
> >> -josh
> >>
> >>> On Mon, May 21, 2012 at 5:37 PM, Josh Blum <j...@ettus.com> wrote:
> >>>
> >>>>
> >>>>
> >>>> On 05/21/2012 03:09 PM, Alex Zhang wrote:
> >>>>> Hi,
> >>>>>
> >>>>> What I want to do is try to use the two antennas of SBX
> simultaneously.
> >>>>>
> >>>>> The TX/RX is used for duplex communications and the RX2 is for
> sensing.
> >>>> The
> >>>>> two antennas are working different frequencies.
> >>>>> But this solution seems to be unfeasible, as someone said the
> receiver
> >>>>> chain of SBX is the same. The TX/RX and RX2 can not work
> >> simultaneously.
> >>>>> As suggested in the community, I am trying to using 3 frequecies on
> one
> >>>>> antenna (TX/RX): f1, f2, f3.
> >>>>>
> >>>>> f1(tx) and f2(rx) are used for FDD duplex communications,and f3 is
> for
> >>>>> sensing path. And f2 and f3 are within the 40MHz difference.
> >>>>>
> >>>>> My problem is how to set it in USRP source block for this kind of
> >>>>> configuration? Does anybody has such example? And I met the error
> like
> >>>>> below:
> >>>>>
> >>>>> Runtime error:vector::_M_range_check
> >>>>>
> >>>>> which seems to be caused by incorrect setting of subdev. However, I
> >> don't
> >>>>> know what the valid value fo subdev in such kind configuration.
> >>>>>
> >>>>>
> >>>>
> >>>> Correct, you can only receive from one antenna at a time. If your RX
> >>>> frequencies of interest are reasonably near in frequency, lets say 40
> >>>> MHz, you can use multiple DSPs in the FPGA as a kind of 2 channel
> >>>> filterbank.
> >>>>
> >>>> You can set the subdev/frontend spec to "A:0 A:0", this will map the
> >>>> frontend A:0 to both DSP0 and DSP1. If you setup the USRP source for 2
> >>>> channels, DSP0 will be output 0 and DSP1 will be output 1.
> >>>>
> >>>> Be careful with the tune_request so that you are setting the rf
> >>>> frequency to the same setting, but with different target frequencies
> to
> >>>> get the DSPs to shift appropriately. There should be some mention of
> >>>> tune request in the docs inside the USRP source block properties
> dialog
> >>>> in GRC.
> >>>>
> >>>> -josh
> >>>>
> >>>>>
> >>>>>
> >>>>> _______________________________________________
> >>>>> Discuss-gnuradio mailing list
> >>>>> Discuss-gnuradio@gnu.org
> >>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >>>>
> >>>> _______________________________________________
> >>>> Discuss-gnuradio mailing list
> >>>> Discuss-gnuradio@gnu.org
> >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >>>>
> >>>
> >>>
> >>>
> >>
> >
> >
> >
>
--
Alex,
*Dreams can come true – just believe.*
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