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 >>> >> > > > _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
