On 02/17/2011 01:57 PM, Feng Andrew Ge wrote: > I posted one question in an early email, but it might be better to put > it together with other questions here. I'd greatly appreciate your answers. > > (1) When transmitting UHD packets (with USRP2 + WBX), after each > transmission, there is either one or a few "U" printed out. What does > "U" mean? Is it used in the update packet from USRP2 to the host? >
Underflow on transmit = host not producing samples fast enough. If you are concerned about performance, I encourage you to checkout the "next" branch on uhd.git and see if you get less underflows. > (2) In uhd:usrp:single_usrp, there is a function "read_rssi", is this > function enabled? If so, does it mean that we can read RSSI value > directly from USRP2? I suppose that this function is implemented on the > FPGA since there exits a rssi.v function in the uhd library. > This function is daughterboard dependent and only works with the XCVR2450. > (3) In uhd:usrp:single_usrp, it seems that "get_rx_rate" is for setting > sampling rate, but then what is "get_rx_bandwidth" for? > It tells you the IF bandwidth of the daughterboard. > (4) In flow control, how to specify "ups_per_fifo", just like > device_address["ups_per_fifo"] = "xx"? Also, what are the FIFOs on USRP2 > and what are their default sizes? > Yes but I recommend using the default. And the FIFO is the 1MB SRAM on the USRP2. > (5) For "concurrency_hint", it says "the number of threads to run the IO > service", does it mean the total number of threads associated with the > UDP socket for each USRP_SINK or USRP_SOURCE, or something else? > These are background threads that run the recv() and send() calls on the udp socket. If you switch to the next branch, this has been removed. > (6) Do control messages generated by functions like get/set_tx_gain and > get/set_tx-freq have to wait on the same UDP buffers which are also used > for exchanging data samples between GNU Radio and USRP? > No, control is independent from data. -josh _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
