Hi Josh,
can you explain how and why the frequency translation occurs?
secondly when the same basic tx chip is used on a usrp N210, the
translation occurs at 50Mhz and after. So for USRP N210, the entire range
from 0-250 Mhz is represented by alternating between -50Mhz to +50Mhz. Why
is it that way?
On Fri, Jul 5, 2013 at 1:19 AM, Josh Blum <[email protected]> wrote:
>
>
> On 07/04/2013 01:41 AM, Karan Talasila wrote:
> > Hi Josh,
> > we tried using the same grc flowgraph and tried transmitting
> at
> > frequencies 33Mhz and 35 Mhz. Though we could see a constant source
> output
> > on the fft, the frequency at which that was occuring was at -31Mhz and
> > -29Mhz. The output log is shown below for frequency of 33 Mhz. I have
> > attached a screenshot of my grc too.
> >
>
> That sounds correct. The receive chain performs frequency translation
> with a CORDIC running at 64MHz. So -31MHz is an alias of 33MHz and
> -29Mhz is an alias of 35MHz
>
> -josh
>
> >
> > enerating: "/home/anrc/Downloads/top_block.py"
> >
> > Generating: "/home/anrc/Downloads/top_block.py"
> >
> > Executing: "/home/anrc/Downloads/top_block.py"
> >
> > linux; GNU C++ version 4.6.3; Boost_104800; UHD_003.004.005-0-unknown
> >
> > Using Volk machine: sse4_1_64
> > -- Opening a USRP1 device...
> > -- Using FPGA clock rate of 64.000000MHz...
> >
> > UHD Warning:
> > The hardware does not support the requested RX frequency:
> > Target frequency: 33.000000 MHz
> > Actual frequency: -31.000000 MHz
> > -- Opening a USRP1 device...
> > -- Using FPGA clock rate of 64.000000MHz...
> > U
> >>>> Done
> >
> >
> >
> > On Thu, Jul 4, 2013 at 6:36 AM, Josh Blum <[email protected]> wrote:
> >
> >>
> >>
> >> On 06/29/2013 09:14 AM, Karan Talasila wrote:
> >>> ---------- Forwarded message ----------
> >>> From: Karan Talasila <[email protected]>
> >>> Date: Sat, Jun 29, 2013 at 6:44 PM
> >>> Subject: Re: [Discuss-gnuradio] Problem in uhd_fft
> >>> To: "[email protected]" <[email protected]>
> >>>
> >>>
> >>> Hi Josh,
> >>> I am using USRP 1. I am using a sma-bulkhead cable from
> >> Tx_A
> >>> of basic tx daughter board and similarly a sma-bulkhead cable from Rx_A
> >>> terminal of the Basic Rx daughter board. and then i am connecting a
> >> sma-sma
> >>> cable from usrp transmitter to a coupler on powerline cable. Similarly
> I
> >> am
> >>> connecting a sma-sma cable from usrp receiver to another coupler on the
> >>> powerline cable.
> >>>
> >>> so in all I am using 2 usrp 1, 2 sma-sma cables, 2 sma-bulkhead cable
> and
> >>> two couplers. Please let me know if i am not clear with the
> description.
> >>> Thank you.
> >>>
> >>
> >> Seems to work OK for me. I used a single USRP1, BasicRX, BasicTX. RXA is
> >> connected to TXA and RXB is connected to TXB. Attached is a GRC flow
> >> graph. Hope that helps.
> >>
> >> -josh
> >>
> >>>
> >>> On Sat, Jun 29, 2013 at 11:24 AM, Josh Blum <[email protected]>
> wrote:
> >>>
> >>>>
> >>>>
> >>>> On 06/27/2013 09:44 AM, Karan Talasila wrote:
> >>>>> Hi,
> >>>>> I am using a basic tx and basic rx daughterboard for
> transmission
> >>>> and
> >>>>> reception. The spec says basic tx and basic rx run from 0 to 250 MHz.
> >> But
> >>>>> when i run transmitter and check the uhd_fft at receiver, after 32
> Mhz,
> >>>>> there is no signal. If i set the transmitter frequency in my
> flowgraph
> >> as
> >>>>> 33 MHz, I don't get a signal at 33 Mhz, But when i enter frequency as
> >>>>> -31Mhz in the uhd_fft i get a received signal on my fft. why does
> this
> >>>>> happen? If it's in the range of daughter board it should be receiving
> >> it
> >>>> at
> >>>>> that particular frequency right.
> >>>>>
> >>>>>
> >>>>
> >>>> Can you tell me more about the cabling setup? Which ports of the Basic
> >>>> TX and RX are you using, and how are they connected via SMA cable?
> >>>>
> >>>> -josh
> >>>>
> >>>>>
> >>>>> _______________________________________________
> >>>>> Discuss-gnuradio mailing list
> >>>>> [email protected]
> >>>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >>>>>
> >>>>
> >>>> _______________________________________________
> >>>> Discuss-gnuradio mailing list
> >>>> [email protected]
> >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >>>>
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> Discuss-gnuradio mailing list
> >>> [email protected]
> >>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >>>
> >>
> >
> >
> >
>
--
Regards
Karan Talasila
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