On 09/18/2012 05:36 AM, Ting Wu wrote: > Hi, > > > > I made more tests, and even stranger things happened. Let me clarify this > problem all over again. > >
Well, here is a description of overflow: http://files.ettus.com/uhd_docs/manual/html/general.html#overflow-underflow-notes So, its usually a factor of buffering, interrupts, and CPU performance. It looks like you are connecting a USRP source to a gr messsage queue and reading the queue in python. The python processing might be a serious performance bottleneck -josh > > I have two USRP (N210 Rev.4) (Let's say U1 and U2) with LFRX daughterboard, > and two computers (Endeavo ST160E) (Let's say P1 and P2). > > First, U1 is connected with P1 and running test code (see below) works well. > > U2 is connected with P2, and running the code below prints 'O', indicating > overflow problem. > > > > Then, I connect U1 to P2. Overflow problem happens again, and printing of > 'O' becomes more frequent. > > Then, I connect U2 to P2. Same as above, frequent printing of 'O'. > > Then I rebooted P2, and connect it with U1. No overflow problem. > > Then I connect P2 with U2. Again there is overflow problem. > > Then I rebooted P2 again, and connect it to U2. No overflow problem again. > > > > For P1, there is always overflow problem even if I reboot it and no matter > it is connected with U1 or U2. > > > > This is the code for making tests: > > #######################################code########################## > > > > #!/usr/bin/env python > > > > from gnuradio import gr > > from gnuradio import uhd > > import time > > from time import sleep > > from struct import unpack > > > > samp_rate = 4e6 > > gain = 0 > > > > class trig_with_pretrig(gr.top_block): > > def __init__(self): > > gr.top_block.__init__(self) > > self.source = uhd.usrp_source(device_addr="", > stream_args=uhd.stream_args('sc16', 'sc16', args="scalar=1024")) > > > > self.source.set_samp_rate(samp_rate) > > self.source.set_gain(gain) > > self.source.set_center_freq(0) > > > > self.queue = gr.msg_queue() > > self.sink = gr.message_sink(gr.sizeof_short*2, self.queue, > False) > > self.connect(self.source, self.sink) > > > > > > if __name__=="__main__": > > tb = trig_with_pretrig() > > tb.start() > > > > while True: > > > > #Test speed of computer > > tb.queue.flush() > > for i in range(1000): > > msg = tb.queue.delete_head() > > payload = msg.to_string() > > loadLen = int(msg.arg2()) > > format = str(loadLen*2)+'h' > > data = unpack(format, payload) > > datach1 = data[0::2] > > dataMax = max(datach1) > > wait_len = tb.queue.count() > > sleep(1) > > > > ##########################code ############################ > > > > When there is overflow problem, it is like this: > > > > lrg@lrg:~$ ./test_overflow.py > > linux; GNU C++ version 4.4.3; Boost_104000; UHD_003.004.003-224-gc2e197c0 > > > > -- Opening a USRP2/N-Series device... > > -- Current recv frame size: 1448 bytes > > -- Current send frame size: 1472 bytes > > -- Detecting internal GPSDO.... Found a Jackson Labs GPS > > -- found > > -- Setting references to the internal GPSDO > > -- Initializing time to the internal GPSDO > > OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO > OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO > > > > Anyone has any clue what might be the reason for this overflow problem? > > Any suggestion is appreciated. > > > > Wu > > > > From: discuss-gnuradio-bounces+wu.ting=comf5.comm.eng.osaka-u.ac...@gnu.org > [mailto:discuss-gnuradio-bounces+wu.ting=comf5.comm.eng.osaka-u.ac...@gnu.or > g] On Behalf Of Ting Wu > Sent: Tuesday, September 18, 2012 5:36 PM > To: discuss-gnuradio@gnu.org > Subject: [Discuss-gnuradio] Strange overflow problem on USRP N2XX > > > > Hi all, > > > > Now I'm using several USRP N200 and N210 to build an observation network. > > I have bought several new computers, which are exactly the same. > > When I connect a USRP N210 with one computer, it has overflow problem > (occasionally print 'O'). > > However, when I connect the same USRP with another computer (exactly the > same model), it does not have such problem. > > > > Several months ago, when I used a USRP N200, it also had similar problem. > > When I connect the USRP to a laptop (a very new and fast one), it > occasionally has overflow problem. > > However, when I connect it to other computers (some of them are very old and > slow), it did not have the problem. > > > > This really bothers me because I don't know what is the reason of this > problem, so we are not sure what computers we should buy in future > operation. > > Does anyone have any clue? > > > > Wu > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
