Hi guys, Another quick (couple of) question(s); - The DBSRX2 has a programmable channel filter 1-60 MHz. Is the firmware clever enough to know to increase this bandwidth when I'm reading two separate frequencies, or is there a chance that it will ruin my day by centering a too-narrow filter around what I set as rf_freq? - Does GNU radio provide an interface to manually change the daughterboard channel filter?
Cheers, John On Wed, Feb 13, 2013 at 8:54 AM, John Wilson <johnmwilso...@gmail.com>wrote: > Hey yes I had that bit working okay (found that page before), I was just > wondering how to actually use it, all seems so simple now anyway! It would > be nice to see some simple instructions on those application notes about > how the individual RX chains can be used (pretty much what Josh said > below). Anyway having got back into the lab it all seems to be up and > working, now I've just got to hope I don't hit the bandwidth limit on the > USB :) > > Thanks again, > > John > > > > On Wed, Feb 13, 2013 at 2:23 AM, Josh Blum <j...@ettus.com> wrote: > >> >> >> On 02/12/2013 04:03 PM, Marcus D. Leech wrote: >> >> >> >> On 02/12/2013 12:10 PM, John Wilson wrote: >> >>> Hi, >> >>> >> >>> I'm wondering whether it's possible/how to use a USRP1 with 2x DBSRX >> >>> boards >> >>> to generate 4 separate streams via the 4rx usrp1 firmware. The >> required >> >>> channels will be within the front end bandwidth of the DBSRX2. >> >>> >> >>> At the moment I'm using a subdev spec of 'A:0 A:0 B:0 B:0' which I >> >>> assume >> >>> runs the signal from subdev A through RX chains 0 and 1, and subdev B >> >>> through 2 and 3. Is this correct? >> >> That seems correct. >> >> >> >>> I am planning to set each daughter board to a frequency between its >> two >> >>> frequencies of interest, then I'd like the DDCs to downconvert the >> data >> >>> from the ADC independently to sit the two frequencies of interest in >> the >> >>> centre of their respective baseband channels out of the USB bus. So >> >>> can I >> >>> change the DDC frequencies independently of the centre frequency in >> the >> >> You will want a tune_request object where the rf_freq is set to the >> >> desired center frequency of the DBSRX (something in between that each >> >> CORDIC can shift away from). And set the rf freq policy to manual. >> >> >> >> There are some examples of making the tune request in the grc block for >> >> usrp source properties dialog box. >> >> >> >>> daughterboard? Also what is the resolution of the DDS in the DDC, >> >>> i.e. can >> >>> I tune each one independently in ~1Hz steps? >> >>> >> >> The CORDIC resolution is pretty much 64e6/(1<<32), so sub Hz. >> >> >> >> >> >> -josh >> >> >> > Also, will he need to use the 4rx FPGA image, or will UHD automagically >> > use the right image? >> > >> > >> >> Its an args option, exact example here: >> >> http://files.ettus.com/uhd_docs/manual/html/usrp1.html#specify-a-non-standard-image >> >> -josh >> >> > >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > >
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