4 -----------------------------------------------------------------------
8 -c DDC center frequency, set band.
9 -c 7.2e6 or -c 7.2M for 40 meter ham band.
10 Default is 3.9e6 80 meter ham band.
15 starts up in the 31 meter band.
17 -a Audio output file. Output file for 32kHz two channel
18 signed word audio. Two channels are used for
19 independent sideband. This file can be converted
20 to a wav file with sox. Example:
22 sox -c 2 -r 3200 file.sw file.wav
24 sox needs the .sw extension to indicate file type.
25 If not specified no audio file is created.
27 -r Radio output file. File to write RF data to for later
28 demodulation. Records the entire band to disk, width
29 determined by sample rate/decimation. Be sure to
30 note the decimation and center freq for later use!
33 hfx.py -c 900e3 -d 80 -r rf_data_AM-c900e3-d80
35 writes a pre-demod rf file centered on 900kHz with a
36 bandwidth of 800kHz (That's 80 AM stations!). The
37 center and decimation could be put in the filename for
39 If not specified no rf data file is created.
40 At default 250 decimation disk usage is about
43 -i Radio input file. Use to play back a previously
44 recorded rf data file. Example:
46 hfx.py -c 900e3 -d 80 -i rf_data_AM-c900e3-d80
48 plays back the previously recorded band, no
49 usrp hardware needed. Tune about the 800kHz wide band.
50 When playing a recorded file, time controls
51 fast-forward and rewind are available.
53 -d Decimation. Sets sample rate and bandwidth.
54 This is the factor that the usrp sample rate, 64e6,
55 is divided by. Default is 250 for 256kHz bandwidth
56 which is enough to record a ham band without
57 eating up disk space too fast. The 64e6 sample
58 rate limits the upper practical frequency to 32MHz.
59 The Basic RX transformer limits the lower frequency
65 A Powermate knob is recommended but not necessary. If a knob
66 is used, it is in one of 3 or 4 modes controlling frequency,
67 volume, filter and (if playing a recorded file) time.
68 Pushing the knob switches mode and the buttons on the HFX panel
69 change to show which mode is in effect. Then just turn the knob
70 to set frequency, volume, filter or go fast forward or rewind.
75 Across the top are a set of predefined bands and buttons
76 to rapidly switch to the center of that band. To change a band,
77 type the frequency in Hz into the box under "Center Frequency",
78 then press "Set" on the left, then the button you want to
79 program. From then on (untill the program is exited) pushing
80 that button takes you to that band. To make a band button
81 permenant edit the hfx.py script with whatever frequency you
82 want assigned to what button.
87 There are 6 ways to set the frequency.
88 1) Move the slider with the mouse
89 2) Use the Spin Control up/down arrows (very fine 1Hz control)
90 3) Type the frequency in Hz into the Spin Control
91 4) Turn the Powermate knob
93 6) Clicking on the FFT display to set demod center. This is very
94 convenient for tuning +-15kHz when you see a signal on the
95 display. If in Lower Sideband, clicking just to the right of
96 a signal will tune to it immediately. Clicking several times
97 on the far right right or left of the display will rapidly
98 tune up or down the band.
103 Move the volume slider with the mouse, or push the Powermate knob
104 untill the volume button is active, or click on the volume button,
105 then turn the knob. Volume can also be set by web control if web
106 control is setup and enabled.
111 Similar to volume, switches in any of 30 audio filters from 600
112 to 3600Hz in Sideband or up to 5kHz in AM.
117 Demodulation modes are chosen by clicking on the buttons for
118 Lower Sideband, Upper Sideband, or AM.
123 PGA slider sets the rf gain in the Analog-to-Digital converter
124 before digitizing. 0 to 20db gain easily shows up on the FFT
130 When playing back a recorded RF data file, you can enjoy the
131 freedom of rewinding or fast-forwarding. Replay a weak signal
132 or skip through annoying AM commercials.
135 Antennas and Preamps:
137 The USRP Basic RX board is not sensitive enough for anything but
138 the strongest signals. In my experience about 40 db of small
139 signal gain is required to make the HFX as sensitive as other
140 receivers. Some working amplifiers are the Ramsey PR-2 with 20db
141 gain, fairly low noise and more bandwidth than we can use here.
142 Also the amp modules from Advanced Receiver Research are nice.
143 I use an ARR 7-7.4MHz GaAsFET 29db amp with .5db noise at the
144 apex of a 40 meter dipole with excellent results. Another
145 amp I like is a Minicircuits ZHL-32A 29db amp but they are
146 expensive and hard to find. Also it may help to use some filters
147 to keep strong local signals from the ADC, or limit rf input
148 to the band of interest, etc.
149 Resonant outdoor antennas, like a dipole, in a low-noise (away
150 from consumer electronics) environment are nice. Long random wires
151 with a tuner work. I like a small indoor tuned loop made from 10ft
152 of 1/4" copper tube, a 365pf tuning cap and a pickup loop connected
158 To control your radio remotely, ensure you have a web server
159 (Apache, etc) working and a compatible directory structure in
160 place. Directories /var/www/cgi-bin/commands and
161 /var/www/cgi-bin/state must already exist. You will need a
162 home page with forms and a set of scripts to put commands in
163 and put the current state on the home page. email me for further
164 help. Setting WEB_CONTROL to True in hfx.py turns on the timers
165 that check for commands and update the state.
170 There is a provision for outputting un-demodulated complex
171 through the audio out in stereo for use with Digital Radio
172 Mondial (DRM) or using a seperate demodulation program like
174 Set IF_OUTPUT to True in weaver_isb_am1_usrp4.py.
177 --Good luck and happy LW/MW/SW Exploring.
179 chuckek@musicriver.homeunix.com