# USRP spectrum sensing **URL:** \ **Category:** GNU Radio\ **Created:** [November 12, 2014, 2:58pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031 "2014-11-12T14:58:54Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\ **Post date:** [November 12, 2014, 2:58pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/1 "2014-11-12T14:58:54Z")
When I implement the source code " usrp\_spectrum\_sense.py", the program can be compile but when I enter the start, end frequency and fft size it comes with a error:‘module’ object has no attribute ’stream\_to\_vector. Has anyone meet this error before. and I found some solution : rename the project file and delete filename.pyc if exists, but I don’t know where to find the .pyc file for the stream\_to\_vector, is it included in gr? Any direction or examples will be very helpful for me. Thanks a lot Huihuang [http://gnuradio.4.n7.nabble.com/file/n51288/error.png](http://gnuradio.4.n7.nabble.com/file/n51288/error.png) here I attached the program from gnuradio import gr, eng\_notation from gnuradio import audio from gnuradio.fft import window from gnuradio import uhd from gnuradio.eng\_option import eng\_option from optparse import OptionParser import sys import math import struct from gnuradio import blocks from gnuradio import wxgui import threading sys.stderr.write(“test usrp\_sense-\>huihuang.\n\n”) class ThreadClass(threading.Thread): def run(self): return class tune(gr.feval\_dd): “”" This class allows C++ code to callback into python. “”" def **init** (self, tb): gr.feval\_dd. **init** (self) self.tb = tb ``` def eval(self, ignore): """ This method is called from gr.bin_statistics_f when it wants to ``` change the center frequency. This method tunes the front end to the new center frequency, and returns the new frequency as its result. “”" try: # We use this try block so that if something goes wrong from here # down, at least we’ll have a prayer of knowing what went wrong. # Without this, you get a very mysterious: # # terminate called after throwing an instance of ‘Swig::DirectorMethodException’ # Aborted # # message on stderr. Not exactly helpful 😉 ``` new_freq = self.tb.set_next_freq() return new_freq except Exception, e: print "tune: Exception: ", e ``` class parse\_msg(object): def **init** (self, msg): self.center\_freq = msg.arg1() self.vlen = int(msg.arg2()) assert(msg.length() == self.vlen \* gr.sizeof\_float) ``` # FIXME consider using Numarray or NumPy vector t = msg.to_string() self.raw_data = t self.data = struct.unpack('%df' % (self.vlen,), t) ``` class my\_top\_block(gr.top\_block): ``` def __init__ (self): gr.top_block. __init__ (self) usage = "usage: %prog [options] min_freq max_freq" parser = OptionParser(option_class=eng_option, usage=usage) parser.add_option("-a","--args",type="string",default="", help="UHD device device address ``` args[default=%default]“) parser.add\_option(”“,”–spec",type=“string”,default=None, help=“Subdevice of UHD device where appropriate”) parser.add\_option(“-A”,“–antenna”,type=“string”,default=None, help=“select RX antenna where appropriate”) parser.add\_option(“-s”,“–samp-rate”,type=“eng\_float”,default=1e6, help=“set sample rate[default=%default]”) parser.add\_option(“-g”,“–gain”,type=“eng\_float”,default=None, help=“set the gain in dB[default=%default]”) parser.add\_option(“”,“–tune-delay”,type=“eng\_float”,default=1e-3,metavar=“SECS”, help=“time to delay(in seconds) after changing frequency[default=%default]”) parser.add\_option(“”,“–dwell-delay”,type=“eng\_float”,default=10e-3,metavar=“SECS”, help=“time to dwell (in seconds) at a given frequency[default=%default]”) parser.add\_option(“-F”,“–fft-size”,type=“int”,default=256, help=“specify number of fft bins”) parser.add\_option(“”,“–real-time”,action=“store\_true”,default=False, help=“attempt to enable real-time scheduling”) ``` (options, args) = parser.parse_args() if len(args) != 2: parser.print_help() sys.exit(1) self.min_freq = eng_notation.str_to_num(args[0]) self.max_freq = eng_notation.str_to_num(args[1]) if self.min_freq > self.max_freq: # swap them self.min_freq, self.max_freq = self.max_freq, self.min_freq self.fft_size = options.fft_size if not options.real_time: realtime = False else: # Attempt to enable realtime scheduling r = gr.enable_realtime_scheduling() if r == gr.RT_OK: realtime = True else: realtime = False print "Note: failed to enable realtime scheduling" #build the graph self.u=uhd.usrp_source(device_addr=options.args, stream_args=uhd.stream_args('fc32')) #set the subdevice spec if(options.spec): self.u.set_subdev_spec(options.spec,0) #set the antenna if(options.antenna): self.u.set_antenna(options.antenna,0) usrp_rate=options.samp_rate self.u.set_samp_rate(usrp_rate) dev_rate=self.u.get_samp_rate() s2v=gr.stream_to_vector(gr.sizeof_gr_complex,self.fft_size) mywindow=window.blackmanharris(self.fft_size) fft=gr.fft_vcc(self.fft_size,True,mywindow) power=0 for tap in mywindow: power += tap*tap c2mag=gr.complex_to_mag_squared(self.fft_size) # FIXME the log10 primitive is dog slow log = gr.nlog10_ff(10, self.fft_size, ``` -20_math.log10(self.fft\_size)-10_math.log10(power/self.fft\_size)) ``` # Set the freq_step to 75% of the actual data throughput. # This allows us to discard the bins on both ends of the ``` spectrum. ``` self.freq_step = 0.75 * usrp_rate self.min_center_freq = self.min_freq + self.freq_step/2 nsteps = math.ceil((self.max_freq - self.min_freq) / ``` self.freq\_step) self.max\_center\_freq = self.min\_center\_freq + (nsteps \* self.freq\_step) ``` self.next_freq = self.min_center_freq tune_delay = max(0, int(round(options.tune_delay * usrp_rate / ``` self.fft\_size))) # in fft\_frames dwell\_delay = max(1, int(round(options.dwell\_delay \* usrp\_rate / self.fft\_size))) # in fft\_frames ``` self.msgq = gr.msg_queue(16) self._tune_callback = tune(self) # hang on to this to ``` keep it from being GC’d stats = gr.bin\_statistics\_f(self.fft\_size, self.msgq, self.\_tune\_callback, tune\_delay, dwell\_delay) ``` self.connect(self.u, s2v, fft, c2mag, stats) if options.gain is None: # if no gain was specified, use the mid-point in dB g = self.u.get_gain_range() options.gain = float(g.start()+g.stop())/2.0 self.set_gain(options.gain) print "gain =", options.gain def set_next_freq(self): target_freq = self.next_freq self.next_freq = self.next_freq + self.freq_step if self.next_freq >= self.max_center_freq: self.next_freq = self.min_center_freq if not self.set_freq(target_freq): print "Failed to set frequency to", target_freq sys.exit(1) return target_freq def set_freq(self,target_freq): r=self.u.set_center_freq(target_freq) if r: return True return False def set_gain(self,gain): self.u.set_gain(gain) ``` def main\_loop(tb): while 1: #get the next message sent from the c++ code(blocking call) #it contains the center frequency and the mag squared of the fft m=parse\_msg(tb.msgq.delete\_head()) #print center freq so we know that something is happening print m.center\_freq #print m.data if **name** ==‘ **main** ’: t=ThreadClass() t.start() ``` tb=my_top_block() try: tb.start() main_loop(tb) except KeyboardInterrupt: pass ``` – View this message in context: [http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288.html](http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![Leo\_Yang](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/439d5e/32.png) [@Leo\_Yang](https://www.ruby-forum.com/u/Leo_Yang)\ **Post date:** [November 12, 2014, 3:04pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/2 "2014-11-12T15:04:17Z")
stream to vector is a block that comes with GNU Radio. If python can’t find that, you have not installed GNU Radio correctly. Best regards, Marcus ---
**Author:** ![Leo\_Yang](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/439d5e/32.png) [@Leo\_Yang](https://www.ruby-forum.com/u/Leo_Yang)\ **Post date:** [November 12, 2014, 3:09pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/3 "2014-11-12T15:09:40Z")
But when i run the other programs which include stream\_to\_vector function, they all works well, it quiet confused me – View this message in context: [http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51290.html](http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51290.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![Leo\_Yang](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/439d5e/32.png) [@Leo\_Yang](https://www.ruby-forum.com/u/Leo_Yang)\ **Post date:** [November 12, 2014, 3:37pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/4 "2014-11-12T15:37:08Z")
That confuses me, too 😉 Is this the usrp\_spectrum\_sense.py from your own installed GNU Radio or did you get it somewhere else? Greetings, Marcus ---
**Author:** ![Leo\_Yang](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/439d5e/32.png) [@Leo\_Yang](https://www.ruby-forum.com/u/Leo_Yang)\ **Post date:** [November 12, 2014, 3:56pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/5 "2014-11-12T15:56:50Z")
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 As you can see, yes, it does really matter… that specific commit is _seven_ years old… Why would you want to use that old version of the file? On 11/12/2014 03:39 PM, Leo Yang wrote: > – View this message in context: > [http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51293.html](http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51293.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). > \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Discuss-gnuradio > mailing list [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJUY3TIAAoJEAFxB7BbsDrLpM8H/2Ru4d//v0y78H6J2J0K/foq F147iHHKk2NGRYLrEf7+1oiR+S9KO4OvWTH9BOy4uS0oYenYk9IXaFYMwkp0/G7Y FDVsOgeEFYn6YNFVRRX0HXngkNo3OGOSNBF2rS02EfaM1GAuTeK9lMWrGS/o9fi2 6nzuL22F8+xNe1YyMBaa32fOkjIqseX2/e+MF+e1888W3BJOqvbeZMc2rP1OLFpb 82vR701Y7n6OXFGVLyqX8eJRCUxN+075k0YV0kJXI/wpwItM56+DjIQtV3yGxNqr UKus7bULRbZvYCRt8V5erwP6ttdz9E8kVKncsx2Dqx0sibVQUykLTlepJvP91Gg= =O6YR -----END PGP SIGNATURE----- ---
**Author:** ![Leo\_Yang](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/439d5e/32.png) [@Leo\_Yang](https://www.ruby-forum.com/u/Leo_Yang)\ **Post date:** [November 12, 2014, 3:52pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/6 "2014-11-12T15:52:03Z")
Thanks a lot for ur replay first, i got the source code from [http://gnuradio.org/redmine/projects/gnuradio/repository/revisions/9880e7bb383054aa43681b52ebd33c8fd4cb8fcb/entry/gnuradio-examples/python/usrp/usrp\_spectrum\_sense.py](http://gnuradio.org/redmine/projects/gnuradio/repository/revisions/9880e7bb383054aa43681b52ebd33c8fd4cb8fcb/entry/gnuradio-examples/python/usrp/usrp_spectrum_sense.py) and a bit modified has been made. u said “get it somewhere”, u mean download and run the program directly , does it really matter ? do u have the USRP device beside u now, it may be helpful to figure out. – View this message in context: [http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51293.html](http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51293.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![Leo\_Yang](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/439d5e/32.png) [@Leo\_Yang](https://www.ruby-forum.com/u/Leo_Yang)\ **Post date:** [November 12, 2014, 4:09pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/7 "2014-11-12T16:09:58Z")
I do have modified the code, and I made this program based on the tutorial video in Youtube [![](https://img.youtube.com/vi/DiVvnMJsVBg/maxresdefault.jpg "GNURADIO : Spectrum sensing with USRP part-1") ](https://www.youtube.com/watch?v=DiVvnMJsVBg) which seems like two years ago stuff. I’m not sure whether it fit the latest version of gnuradio. I just found there are some head file difference and flow\_graph-\>top\_block, is there anything else i should consider? sorry for my ignorance – View this message in context: [http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51295.html](http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51295.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![Leo\_Yang](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/439d5e/32.png) [@Leo\_Yang](https://www.ruby-forum.com/u/Leo_Yang)\ **Post date:** [November 12, 2014, 4:12pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/8 "2014-11-12T16:12:57Z")
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Don’t worry, the things you’ll have to change to make your code work with current GNU Radio aren’t so big, but I think you will notice yourself when reading the current version of the file. However, I’d wonder how you ended up with a link to a version from 7 years ago, would you mind telling us? Greetings, Marcus On 11/12/2014 04:02 PM, Leo Yang wrote: > – View this message in context: > [http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51295.html](http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51295.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). > \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Discuss-gnuradio > mailing list [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJUY3iyAAoJEAFxB7BbsDrLO1cH/AzPp/y3mRIP5rCh+B0W0z24 mYxic97eHYGaOUt2dGUScCRsClBYDRb8MW9/U6OcqTHaBbo39UempCO8rndUR4Yq mXjevba/DrTeN6zbWOiPtybB887x+6CvOSkqOQTVcKMCutjuOagsgZHBcgBNa/7i 7yKbTQKx8X8Zn5j/9xdSlBvT+S/ZS44Wt9l+GftZPQQsx/G32GaQzTwwWBUT1DUF uIk6Wr/yMIJ0pc3vyLReNYuxVvj+52YdYjfntnkwV73wQJeZXPZYx7enl7gUSVcP hJkLehPWKxxxSHy72+RRLe1pvL10xs4RspxhLl1+cae7vUTfjpRQsDvVo4RsybM= =e1K5 -----END PGP SIGNATURE----- ---
**Author:** ![Leo\_Yang](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/439d5e/32.png) [@Leo\_Yang](https://www.ruby-forum.com/u/Leo_Yang)\ **Post date:** [November 12, 2014, 4:40pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/9 "2014-11-12T16:40:25Z")
When i search the usrp spectrum sensing stuff, this source code is first comes out, and there is some relative explanation of this program, and I just met gnuradio few weeks ago. btw, where to find the current version file of gnuradio – View this message in context: [http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51297.html](http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51297.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![Leo\_Yang](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/439d5e/32.png) [@Leo\_Yang](https://www.ruby-forum.com/u/Leo_Yang)\ **Post date:** [November 12, 2014, 4:43pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/10 "2014-11-12T16:43:24Z")
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > **[GitHub - gnuradio/gnuradio: GNU Radio – the Free and Open Software Radio...](https://github.com/gnuradio/gnuradio)** > > GNU Radio – the Free and Open Software Radio Ecosystem Information like that can always be found on the GNU Radio project website, [http://gnuradio.org](http://gnuradio.org). On 11/12/2014 04:33 PM, Leo Yang wrote: > Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). > \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Discuss-gnuradio > mailing list [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJUY3/eAAoJEAFxB7BbsDrLslkH/2iD0Ii2wziunq4pTRXFTfKS 9hMBHn+Nfu+K2l2MoE4CrC4up7DW0VurqpV1/QGaK4bRwwx9MkuXhCL/ql7QMgF7 3ff+nb+3JI4q45VRFoNWdHeMbw2Ffrx2O2bcHcddnMDYOZb2c3EJnOFSR6FKMZuT l0gZZUghySniBH7pvkcB9GXVa7QwgmBtZsquk/3baOMv8kq01vWoaGD6w+yRxBR6 zSkpmi5POKfVTfYqxMlwMJARJ4j/OObcKa0ipk/XjgQ/rwcwvlIq/ksO3KaDrC/p T8bstICOfXT6yOkltUZEncgoOErzgBAvALodJ0ZdQxAcyU5d5lVTn7HM7ko6CgM= =0Y4e -----END PGP SIGNATURE----- ---
**Author:** ![Leo\_Yang](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/439d5e/32.png) [@Leo\_Yang](https://www.ruby-forum.com/u/Leo_Yang)\ **Post date:** [November 12, 2014, 6:02pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/11 "2014-11-12T18:02:48Z")
Thanks very mush sir, the program now is working. – View this message in context: [http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51300.html](http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51300.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com). ---
**Author:** ![Leo\_Yang](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/439d5e/32.png) [@Leo\_Yang](https://www.ruby-forum.com/u/Leo_Yang)\ **Post date:** [November 12, 2014, 5:32pm UTC](https://www.ruby-forum.com/t/usrp-spectrum-sensing/233031/12 "2014-11-12T17:32:21Z")
Thanks again, I found the problem where it comes, it seems in latest version, I did not import Blocks in the begin, hence the program seems can find stream\_to\_vector function 😉 But a same error comes with fft\_vcc which is included in fft,which has already imported [http://gnuradio.org/doc/doxygen/classgr\_1\_1fft\_1\_1fft\_\_vcc.html](http://gnuradio.org/doc/doxygen/classgr_1_1fft_1_1fft__vcc.html) I tried “from gnuradio.fft import fft\_vcc” and it failed, it seems the program can’t find the fft\_vcc ☹ – View this message in context: [http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51299.html](http://gnuradio.4.n7.nabble.com/USRP-spectrum-sensing-tp51288p51299.html) Sent from the GnuRadio mailing list archive at [Nabble.com](http://Nabble.com).