Re: [Discuss-gnuradio] [USRP-users] how to resolve the uhd warning of sample rate

[alok ranjan]

Dear Marcus,

Thank you so much for your help :).  It worked fine.

Regards!
Alok

> Date: Fri, 28 Nov 2014 11:38:29 +0100
> From: address@hidden
> To: address@hidden; address@hidden; address@hidden
> Subject: Re: [USRP-users] [Discuss-gnuradio] how to resolve the uhd warning of sample rate
>
> Hello Alok,
>
> the problem here is that you implicitly request a lower sampling rate
> than your USRP is able to provide:
> "-r 250e3" specifies the bit rate. For "-m qam" (with a default number
> of constellation points (-p) of 16=2^4) this means that the symbol rate
> is 1/4 of that,
> (250e3 b/s) / (4 b/sym) = 62500 sym/s. Now, the default setting for
> samples per symbols (-S) is 2, so that you get 125e3 S/s, which is half
> of what you can minimally do with your USRP.
> You can either use a constellation with less points, increase your bit
> rate, or increase your samples per symbol.
>
> Greetings,
> Marcus
>
>
> PS: can you please generally reply to the mailing list and not to people
> individually? It's a bit hard for me to keep track of this, and it might
> be really frustrating for the others that follow these lists ;)
>
>
> On 11/28/2014 11:20 AM, alok ranjan wrote:
> > Hello Marcus,
> >
> > Thank you for your quick response.
> >
> > I am running the benchmark_tx.py and benchmark_rx.py for transmission and reception. Below is the details what i am getting :
> >
> >
> > python benchmark_tx.py -f 986M -m qam -r 250e3 -A TX/RX --tx-gain=30 -a serial=49270a48
> > linux; GNU C++ version 4.8.2; Boost_105400; UHD_003.005.002-0-unknown
> >
> > Using Volk machine: sse4_2_64_orc
> > -- Opening a USRP1 device...
> > -- Using FPGA clock rate of 64.000000MHz...
> >
> > UHD Warning:
> > The hardware does not support the requested TX sample rate:
> > Target sample rate: 0.125000 MSps
> > Actual sample rate: 0.250000 MSps
> >
> > Symbol Rate: 62500.000000
> > Requested sps: 2.000000
> > Given sample rate: 250000.000000
> > Actual sps for rate: 4.000000
> >
> > Requested sample rate: 125000.000000
> > Actual sample rate: 250000.000000
> >
> > Looking forward for your response.
> >
> > Regards!!
> > Alok
> >
> >
> >
> >
> >> Date: Fri, 28 Nov 2014 10:29:39 +0100
> >> To: address@hidden
> >> Subject: Re: [USRP-users] [Discuss-gnuradio] how to resolve the uhd warning of sample rate
> >> From: address@hidden
> >>
> >> Hi Alok,
> >>
> >> usually, it should say something like "actual sampling rate: XXX". What
> >> does it say? (actually, can you just copy&paste the whole warning?)
> >>
> >> What program are you passing "-r" to?
> >>
> >> Greetings,
> >> Marcus
> >>
> >> On 11/28/2014 08:57 AM, alok ranjan wrote:
> >>> Dear All,
> >>>
> >>>
> >>> I am using USRP1 having RF daughterboards WBX (50Mhz -2.2Ghz). I have
> >>> gone through some basic details of the USRP1 product features but dont
> >>> know how to resolve the errors oh UHD warning saying the hardware
> >>> doesnot support the target tx sample rate and same for the rx also.
> >>>
> >>>
> >>> Below is the USRP1 supported features :
> >>>
> >>> ADC sample rate: 64MS/s
> >>> DAC sample rate:128MS/s
> >>> Host sample rate: 8 for usb2
> >>> FPGA clock rate: 64Mhz
> >>>
> >>> Please help me to understand that what value of -r i should pass for the both tx and for rx.
> >>>
> >>> I
> >>> have tried with -r 250e3 and 125e3 but it could not work and popping
> >>> the warning that target tx and rx rate is not supported by hardware.
> >>>
> >>> Thank you.
> >>>
> >>>
> >>> _______________________________________________
> >>> Discuss-gnuradio mailing list
> >>> address@hidden
> >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >>
> >>
> >> _______________________________________________
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> >> address@hidden
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> >
>