Re: [Discuss-gnuradio] switching between signal and reference source
On Thu, Apr 15, 2010 at 17:19, Marcus D. Leech wrote: > OK, so Josh, how do you get access to usrp2.source_16sc from GRC? There isn't a source for that. You would need to create a hierarchical block with the needed blocks and wrap in a GRC wrapper. Johnathan ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] switching between signal and reference source
> > On Thu, Apr 15, 2010 at 16:52, Marcus D. Leech wrote: > > > If you are willing to give up an LSB, you can turn on GPIO streaming > with enable_gpio_streaming(). Then io_rx[15] will show up in the lsb > of I, and io_rx[14] will show up in the lsb of Q. You need to use the > usrp2.source_16sc source to get the raw samples, then gr_and_const to > separate the digital bit from the rest of the sample. > > The io bits get stuffed as the samples come out of the DDC, so there > is a fixed offset (you'll need to measure it) based on the group delay > through the whole analog front-end and FPGA DDC. The delay is > decimation dependent, but deterministic. > > Johnathan > > > OK, so Josh, how do you get access to usrp2.source_16sc from GRC? -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] switching between signal and reference source
On Thu, Apr 15, 2010 at 16:52, Marcus D. Leech wrote: > Can I use the GPIO stuff to give me better confidence of adequate > synchronization between the > actual data, and the state of the input? If you are willing to give up an LSB, you can turn on GPIO streaming with enable_gpio_streaming(). Then io_rx[15] will show up in the lsb of I, and io_rx[14] will show up in the lsb of Q. You need to use the usrp2.source_16sc source to get the raw samples, then gr_and_const to separate the digital bit from the rest of the sample. The io bits get stuffed as the samples come out of the DDC, so there is a fixed offset (you'll need to measure it) based on the group delay through the whole analog front-end and FPGA DDC. The delay is decimation dependent, but deterministic. Johnathan ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] switching between signal and reference source
I'm buliding a system that switches the RF input, several times per second, between the actual signal, and a stable reference source. On a USRP2, what kind of latency is there between the antenna input, and data arriving at the head of the signal processing chain? Small errors at the 'edge' of the switching time are acceptable, but I don't want to get into a situation where my *notion* of whether the input is connected to the source or the reference is horribly out of what. Can I use the GPIO stuff to give me better confidence of adequate synchronization between the actual data, and the state of the input? -- Principal Investigator Shirleys Bay Radio Astronomy Consortium http://www.sbrac.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
