G4AKW

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...

An alternative to the Collins 300 Hz CW filter for the FT817 (well not really - that combination is excellent for CW and much better performance than many more expensive radios - but this is an excellent sw alternative) is this simple GNU Radio Python application which uses the Kaiser CW bandpass FIR filter below. The audio output is connected to the microphone input of a Ubuntu 11.10, 64bit OS on a Toshiba Satellite L650 laptop. Output is from the laptop headphone socket. Python code is as follows: #!/usr/bin/env python #------------------------------------------------------------------------------------ # Program uses the (previous) Python Bandpass filter # module to provide the Kaiser bandpass filter taps. # Mic input, cw filter, gain adjust and headphone    # blocks are cascaded.                               ...