I am trying to record data directly from a UDP stream to file. I have four channels at 1.2MHz sample rate the code is below. Basically it opens a UDP source and connects to a file sink. However, It is losing data when writing to the file. If I stream a signal with a one second burst the spacing is not correct. Also, I have another c++ program that reads the UDP packets and records directly to file, and there are no lost UDP packets nor lost data with this program. Also I have checked that the UDP packet size is less than 1472, it is currently at 1024 bytes.
Is there a way to see if file_sink is not able to handle that data rate, or to see if the UDP source cannot keep up?
#!/usr/bin/env python
from gnuradio import gr from gnuradio.wxgui import waterfallsink2, stdgui2, fftsink2,scopesink2 import wx from optparse import OptionParser from gnuradio.qtgui import qtgui import os import time import thread import threading
class gnuradioGUI(stdgui2.std_top_block): def __init__(self,frame,panel,vbox,argv): stdgui2.std_top_block.__init__(self,frame,panel,vbox,argv) self.sr = 1200000 self.channels = 4 self.FileLength = 5 #seconds of data in each file self.filenum = -1 self.baseName = "udp_1k." self.file_increment() self.ipAdd = "192.168.100.178" #the ip of this computer self.port = 3456 self.bufSize = self.channels*4096
self.signal = gr.udp_source(gr.sizeof_short,self.ipAdd,self.port)
self.Update() self.thread = threading.Thread(target=self.FileThread) self.thread.start()
def Update(self): self.lock() try: self.disconnect(self.signal,self.dest) except: print "could not disconnect" self.file_increment() self.dest = gr.file_sink(gr.sizeof_short,self.saveFile) self.connect(self.signal,self.dest) self.unlock()
def FileThread(self): while 1: time.sleep(self.FileLength) self.Update()
def file_increment(self): self.filenum = self.filenum + 1 self.saveFile = self.baseName + "%d"%self.filenum print "writing to file: " + self.saveFile
if __name__ == '__main__': app = stdgui2.stdapp(gnuradioGUI,"CAIS signal using GNU Radio GUI")
parser = OptionParser() parser.add_option("-w", "--file", dest="filename", help="write data to FILE", metavar= "FILE") (options, args) = parser.parse_args()
app.MainLoop()
os._exit(1)
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