readme

这是用python语言写的一个数字广播的信号处理工具包。利用它

hfx.py is meant to be a full-featured Long Wave / Medium Wave
and Short Wave (250kHz to 30Mhz) AM and Single Sideband receiver.
It uses the USRP with a Basic RX board, and will need an
antenna and some preamps, about 30db gain will work. See the
'Help' menu or hfx_help for more info.

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hfx2.py is a major revision built about complex fir filter
coeffecients ability and cleaner python script. Inherits
most features from hfx.py - Powermate knob supported but
not required, tooltip frequency display, single click
tuning, AGC, record to disk, play from disk and record audio.
New feature is ability to tailor the audio passband with two
sliders over the spectrum display. The sliders almost align
with the actual frequency. Preset filter settings for LSB
(-3000 to 0kHz), USB (0 to +3000kHz), CW (-400 to -800Hz)
and AM (-5kHz from carrier to +5kHz).

AM now switches in a synchronous PLL detector with the
carriers at 7.5kHz. The PLL carrier is displayed in the
bottom display and helps show where on the upper spectrum
the demodulated signal lies. Everything gets shifted up
7.5kHz in AM, center frequency, tooltips, etc.  The target
AM carrier needs to be closely tuned in, it will have a
hollow sound untill it is locked, and then the PLL carrier
in the bottom display will jump up and remain relatively 
constant. There is a slider "AM sync carrier" to play with
different levels to mix with the signal for demodulation.
The filter in AM is preset to 2500/12500 (7.5kHz +/- 5kHz)
and is handy for removing adjacent channel interference.
Change AM_SYNC_DISPLAY in script for whether to show AM
Sync carrier or not.
Run with "-h" for command line help with setting USRP 
ddc center frequency, decimation, rf data record, playback
and audio data recording.

There are some controls for controlling a varactor and
tuning an antenna - just ignore them unless you want
to build a voltage tuned antenna to track frequency.

There is also code for Web based control of frequency and
volume - so I can tune the radio with an Ipaq from bed.
Disabled by default - it takes a web server, some
directories and scripts to use.