What is baudline?
Mystery Signal
Full screen snapshots
Click on the thumbnails to see the larger images.

-session wolf
Wolves howling at the California Wolf Center.  These harmonic rich wolf traces are intertwined in a complex display of spectral dominance and unity.  For more information about this real-time acoustics sensors project see the HPWREN news page.

-session matrix
Whoa!  This is a spectrogram of an "amateur radio contest in progress" at 14.200 MHz.  About 25 different LSB and USB conversations are visible in this wideband display.  The hf_14200khz_512_complex.dat.bz2 raw data file on KD7LMO's OTA webpage was opened by baudline's Raw Parameters window with the following settings:
  • decompression: auto magic (for bzip2)
  • sample rate: custom 512000 (512 ksps)
  • channels: 2
  • quadrature enabled
  • decode format: 32 bit float (little endian)
  • normalization: auto measure
or the raw parameters can be preset from the command line with:
  • baudline -quadrature -channels 2 -format le32f -samplerate 512000

The window manager is Gnome's Metacity with the Bluecurve theme.

-session wide_narrow
Baudline wideband and narrowband views of the same real-time recorded signal with the help of UNIX pipes.

The upper half of the screen is baudline recording from a microphone at a 48000 sample/second rate.  The scrolling is a smooth 60 FPS.  This noisy looking signal is then piped to the standard input of a second baudline instance recording in the lower half of the screen at a 375 sample/second rate.  This reduction in sample rate is achieved by using a decimation ratio of 128.  The scrolling is a very slow one frame every couple seconds and the past 18 minutes of signal are visible.  At the bottom are the fundamental Hz and dB measurement windows which are tracking the 60 Hz AC powerline bleed-in. 

This baudline setup was created with the following command line option:
  • baudline -session upper -samplerate 48000 -stdout | baudline -session lower -samplerate 48000 -decimateby 128 -stdin
The window manager is KDE 3.2's kwin with the Plastik theme.

-session imic
The full-duplex noise characteristics of a Griffin iMic USB audio device are being measured.  A short patch cable connects the output to the input in a loopback fashion and baudlines's Tone Generator is the signal source.  The input and output mixer gains have been adjusted for maximum SNR.  The top part of the spectrogram shows a linear sine sweep.  Notice that the harmonics are aliased in a crisscross lattice.  The test source of the noise measurements is a 750 Hz sine wave that is shown in the bottom part of the spectrogram. 

The purple noise measurements are from the digital loopback of the tone generator and have a respective 95 dB SNR and ENOB of 15.4 bits.  Here are the green noise measurements from the iMic:
  • frequency offset = 0.1297 Hz which is an error of 173 PPM.
  • SNR = +73.57 dB
  • THD = -77.86 dB which is 0.000001635 %
  • SINAD = +71.92 dB
  • ENOB = +11.65 bits
  • SFDR = +76.05 dB
The window manager is KDE 3.2's kwin with the Plastik theme.

-session flower
The vibrant yellow-pink-blue color palette was selected in the Input Channel Mapping window.  Two wideband impulse signals with room reverb tails are visible in the main spectrogram window.  On the right are waveform and histogram thumbnail viewers with a couple of measurement windows below.  The window manager is Gnome's Metacity.

-session basso
Using baudline as a continuous data logging tool to capture everything bass (including infrasound).  Door slams, planes, helicopters, cars, lawn mowers, refrigerator compressor cycles, forced air furnaces, and computer fan noise all emit interesting bass signatures and they are all showcased in this very busy spectrogram display!

Here is a description of the setup:
  • baudline -session basso
  • A standard PC microphone with an inexpensive audio card was used which explains the strong 60 Hz (plus harmonics) bleed in.
  • An effective rate of 500 samples/sec was configured in the Input Devices window by setting the sample rate to 8000 with a decimation ratio of 16.
  • 117 MB of buffer space was allocated in the Scroll Control window for more than 18 hours of capture time.
  • The Drift Integrator's anti-alias on spectrogram zoom feature was enabled.
  • The intensity resolution of the color depth was maximized by setting the Color Aperture window's upper and lower color ramp range to -37 dB and -100 dB.
  • FVWM2 window manager


-session modulatori
Creating a frequency modulated sine wave with baudline's Tone Generator window.  Both the /dev/audio microphone and the tone generator loopback channels are enabled in the Input Devices window.  Baudline is in record mode, it is in motion, the response is quick and real-time, everything is fluid, the spectrogram is smoothly scrolling upward at a high rate of speed, and about 600 FFT transforms per second are being calculated.  It is a beautiful sight to behold.  KDE3's kwin is the window manager in this screenshot.

-session visual
Four instances of baudline being used for test signal file visual browsing and playback.  The window manager is KDE1's kwm.

-session capture
Capturing a voice signal from a relatively clean USB microphone.  The Histogram window shows the probability distribution of the sample amplitudes collected from the microphone.  The Waveform window is zoomed out to a timebase factor of 192X to reveal 1.5 seconds of time series data.  The window manager is KDE3's kwin.

Separate windows

Baudline is a time-frequency browser and this is the main window view.  The upper section is the sonogram display which is a plot of frequency vs. time with intensity being energy.  The lower section is a spectrum display which is a standard frequency vs. energy (dB) plot.  The scrollbar on the right is used to navigate around within a larger file.  Zooming in and out is possible and the window pane and window dimensions are completely user adjustable.  The main control menu is accessed as a popup menu by pressing and holding down the third mouse button. 


The Waveform window is a time vs. sample amplitude view of the signal much like that of an oscilloscope.  This is the common view which is typically seen in visual audio applications.  Zooming in and out on both axes is allowed as is scrolling.  The cursor is locked between this window and the main window.  Same data, just a different view.


Like in statistics the Histogram Window is a way of measuring the signal amplitude distribution.  Energy dB (sample amplitude) across the top axis vs. a sum of counts (hits) on the side axis.  This window is zoomable and scrollable in both dimensions.  The famous bell shaped curve was created with the internal White Gaussian Noise function in the Tone Generator. 


The Average window collects and sums frequency spectrum and then averages them over time for long term smoothing function.  Averaging is also useful for pulling low level signals out of the noise floor.  Twelve selection banks are available for holding captured snapshots for quick and easy comparison.  These average spectra can loaded and saved as ASCII data files.  This window is zoomable in both the Hz and the dB axis. 


The Play Deck is more than just the controls found on a common tape deck. It has 12 programmable section banks that can be used for looping or bookmarks.  The playback speed, pitch, and scale (heterodyning) can be changed real-time when playing.  Also a mono or stereo signal can be positioned two dimensionally in a 2 channel matrix surround output.  The lower right popdown button reveals many other playback functions such as loop and phonograph needle scratching controls, notch and low/high pass filters, other matrix, gain boost, and mixing controls. 


The Input Devices window is used for the initial setup and calibration of various low level input side parameters like sample rate, decimation ratio, channel enable and selection, mixer gain, DC offset, and channel delay.  It also reports the name and duplex type of the installed audio devices.  A higher level mapping of the devices to the display channels, input operations, and analysis functions is setup in the Channel Mapping window. 


The Tone Generator is used as a test signal source. Sine, triangle, square, sawtooth, various pulses, and noise types are options and they can be modulated by frequency, amplitude, pulse, and sweep modes.  The Tone Generator output can even be internally loop backed in the Input Devices window so the pure digital test signal can be compared with the device under test.  Surround channel and Complex two channel 90° phase separated output are also options. 


The Color Picker allows the user to customize the color ramps used in the main sonogram window.  The variable RGB gain and exponential sliders allow control of the individual color ramp shapes.  A larger palette of default color ramps are selectable in the Input Channel Mappings window. 


More images

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