See also http://gnuradio.org/redmine/projects/gnuradio/wiki/FAQ#I-have-a-receiver-with-acoustic-output-and-keep-getting-aUaUaU-errors
-- M On 03/05/2017 05:30 PM, Marcus D. Leech wrote: > On 03/05/2017 06:47 PM, Fernando wrote: >> Yes, this USRP has "very strange" sample rates, like 2.631579 MSps the >> are far from rounded values, every single sample rate I try to use, it >> change it to a slightly different one. 2.64Msps came from using a >> sample rate over 2Msps, with a 44Ksps in audio and interpolating in >> two stages one the FMTransmit (QuadratureRate/AudioRate =6 ) which >> must be an integer and a second stage in the resampler (10), so >> 44K*60=2.64M Using a UHD USRP source instead of osmocom source for the >> USRPit works fine (it sound okay), altough some aUaU keep appearing >> (maybe for mismatch between in sample rates?) regards > > Not that strange--a USRP N-series device has a master clock of 100MHz. > Sample rates are constrained to be integer fractions of the > master clock rate. The sample rate you show is exactly 100e6/40, but > is not a multiple of 44Ksps. > > The osmocom block simply calls UHD, so in terms of sample-rate, there'll > be no difference. > > Since 44Ksps is not an integer fraction of 100Msps, you'll need to use > an arbitrary resampler. This is exceedingly common in DSP. > Audio subsystems are sample-rate constrained, and SDRs are sample-rate > constrained, and it's very rare that their constraints > "mesh" in useful ways. Doing fractional resampling in the software > part of the flow is MUCH easier than having the hardware do > arbitrary resampling. > > > > > > > _______________________________________________ > 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
