Skip to main content

GNU Radio Waterfall and CW Filter

The following GNU radio application adds a waterfall spectrogram to the previous CW filter program. The plot show 4 CW signals in the audio band (lower sideband) at 7023 kHz. The 700Hz signal is filtered and output to the laptop headphones by the CW bandpass filter. The frequency display is shown after the script which is as follows:

#!/usr/bin/env python

from gnuradio import gr
from gnuradio import audio
from lpf_bpf_class import Bandpass
from gnuradio.qtgui import qtgui
from PyQt4 import QtGui
import sys, sip
 
 
class cw_filter(gr.top_block):
    def __init__(self):
        gr.top_block.__init__(self)
 
        sample_rate = 44100
        out_rate = 8000
        kaiser = Bandpass()
        cw_flr = gr.fir_filter_fff(1, kaiser.bpftaps)

        decimate = int(sample_rate/out_rate)
        Bandpass.cutoff1 = 3000       
        pre_decim = Bandpass()
        dec_flr = gr.fir_filter_fff(1, pre_decim.lpftaps)
        dec = gr.keep_one_in_n(gr.sizeof_float, decimate)

        # Make a local QtApp
        self.qapp = QtGui.QApplication(sys.argv)
        fftsize = 2048

        audio_mic = audio.source(sample_rate, "plughw:0,0")
        amp1 = gr.multiply_const_ff(2.0)
        amp2 = gr.multiply_const_ff(1.0)
        dst = audio.sink (sample_rate, "")

        self.connect (audio_mic, cw_flr, amp1, dst)

        self.thr = gr.throttle(gr.sizeof_float, 100*fftsize)
        self.snk = qtgui.sink_f(fftsize, gr.firdes.WIN_BLACKMAN_hARRIS,
                         0,
                         4000,
                        "CW Kaiser BPF Filter")
                        #True, True, False, True, False)

        self.connect(audio_mic, amp2, self.thr, dec, self.snk)

        self.pyobj = sip.wrapinstance(self.snk.pyqwidget(), QtGui.QWidget)
        self.pyobj.show()

def main():
    tb = cw_filter()
    tb.start()
    tb.qapp.exec_()


if __name__ == '__main__':
    try:
        main()
    except [[KeyboardInterrupt]]:
        pass

Labels:

Comments

Post a Comment

Popular posts from this blog

Digital Bandpass Filter FIR design - Python

The python code generates the Finite Impulse Response (FIR) filter coefficients for a lowpass filter (LPF) at 10 (Hz) cut off using firwin from scipy.  A highpass filter is then created by subtracting the lowpass filter output(s) from the output of an allpass filter. To do this the coefficients of the LPF are multiplied by -1 and 1 added to the centre tap (to create the allpass filter with subtraction). A second LPF is then created with a cutoff at 15 (Hz) and the bandpass filter formed by addition of the LPF and HPF coefficients. The program also generates a test sine wave of a given amplitude and power and to this noise from a Normal distribution is added.  The graph below shows the signal and nois, and the signal (green) after filtering. The input snr is approximately 3dB. The frequency response below shows the passband centered on 12.5 (Hz), the Nyquist frequency is 50 (Hz). from numpy import cos, sin, pi, absolute, arange from numpy.random import normal from scipy.
Post a Comment
Read more

Splunk Cheat Sheet (Linux)

1. set root's password:  sudo su passwd root Enter new UNIX password: < new_root_password > Retype new UNIX password: < new_root_password > passwd: password updated successfully # su - 2. Remove any existing Splunk directories & create user etc: # rm -rf /opt/splunkforwarder # userdel -r splunk # this will remove as above if user splunk's home directory # groupadd siem # useradd -g siem -s /bin/bash -d /home/siem -m siem # vi ~/.profile # chage -I -1 -m -0 -M -99999 -E -1 siem If above fails because of multiple passwd fails: # pam_tally --reset check with #chage -l siem # uname -a # check OS version # dpkg -i splunk-4.3.1...........intel.deb # chown -R siem:siem /opt/splunk # su - siem : $SPLUNK_HOME/bin/splunk start --accept-license : $SPLUNK_HOME/bin/splunk edit user admin -password newpassword -role admin -auth admin:changeme 3. vi ~/.profile (as follows) (OR .bash_profile) # ~/.profile: executed by the command interpreter for log
1 comment
Read more