What s New in Raven May 2006 This document briefly summarizes the new features that have been added to Raven since the release of Raven

Size: px

Start display at page:

Download "What s New in Raven May 2006 This document briefly summarizes the new features that have been added to Raven since the release of Raven"

Sara Bradford
5 years ago
Views:

1 What s New in Raven May 2006 This document briefly summarizes the new features that have been added to Raven since the release of Raven Extensible multi-channel audio input device support Raven 1.3 includes support for multi-channel recording using both NI-DAQ (National Instruments Data Acquisition hardware) and ASIO (Audio Stream In/Out) audio input devices. The NI-DAQ technology provides input capabilities of up to 32 channels with an adjustable voltage range. ASIO devices provide 24-bit audio sample size capabilities. Both of these are Windows platform devices; the Macintosh version of Raven supports Apple s Core Audio, which allows for multi-channel recording. Power Spectra Calculation Raven 1.3 introduces a slight change in the calculation of power spectra. The new method includes energy in the negative frequency bins of the Discrete Fourier Transform, as well as normalization of the power spectrum by the number of points in the DFT window. Power measurements made using this method will differ from the same measurements performed with previous versions of Raven by a multiplicative factor of 2/Nfft (1/Nfft for the zero frequency component). To use this updated power spectra calculation, check the box on the OPTION screen that appears when Raven 1.3 starts for the first time. The new power spectra calculation should be used in cases when measurements need to be consistent with those made in Canary. The power spectra calculation method that Raven 1.3 uses can be changed by editing Raven s preferences file. The performance of the two power spectra calculation methods can be compared by simultaneously opening two instances of Raven, one with the Raven 1.3 method active and the other with the Raven 1.2 method active. To compare the two power spectra calculations in Raven: 1. Start Raven 1.3. This instance of Raven 1.3 will continue to use the current method, which in most cases will be the one that was chosen the first time that Raven 1.3 was started. 2. Without closing the first instance of Raven 1.3, start Raven 1.3 again, so that there are now two instances running simultaneously. The second instance will be altered to use whatever method was not chosen the first time that Raven 1.3 was started. 3. With the second instance of Raven 1.3 active, open (from the Windows menu) the Raven preferences file: Start > Programs > Raven 1.3 > RavenPreferences.txt 4. Scroll to the last line of the text, which should read as either: raven.compatibility.computation.spectrogram=1.3 or raven.compatibility.computation.spectrogram=1.2 This statement indicates the power spectra computation method that Raven is currently using.

2 5. Change the version number 1.3 to 1.2, or vice versa. This change will affect only the power spectra computation method. 6. Save and close RavenPreferences.txt 7. Leaving the first instance of Raven 1.3 open, close, then reopen the second instance of Raven The previous preference settings will continue to apply to the first instance of Raven 1.3 as long as it remains open. So, it uses the power spectra computation method that was set previously, while the second instance uses the power spectra computation method that was just set. Using the current Raven 1.3 power spectra calculation in one instance, and the earlier Raven 1.2.x power spectra calculation in the other instance, open the same file in each and view them simultaneously. Clip Exporter within real-time recorder The Clip Exporter in Raven 1.3 allows sound clips to be saved before the audio data in the real-time recorder leaves the audio buffer. This facilitates making manual selections in a recording while it is recording. When a selection is committed, the audio data in the selection is saved to a file. The Clip Exporter is an alternative to the Schedule Tab with the "Record To File" option. The Schedule Tab option allows a recording to be made each time the red record button is pressed, however, the system needs to be configured to do retroactive recording in order to record sounds that are already in the buffer, and the red button needs to be pressed before the end of the retroactive time limit. In contrast, the Clip Exporter allows a selection to be made at any time within the 30-second buffer. Also, the Clip Exporter is similar to Save Active Selection As, however, it allows all of the names that will be assigned to the files to be pre-configured, since there isn t time to fill in this information before the sound leaves the buffer. Exporting samples from various views to text files A list of the numerical sample values contained in the active view of a sound can be exported to a text file. Highlight the view selection button(s) to the left of the view (waveform, spectrogram, etc.) that you want use by double-clicking. The color will change from white to blue when highlighted. Choose File > Export Sound <x> <selected view> Samples. A suggested name, <FileName>.samplesch<cc>.txt, appears, which provides the option of including an updated channel number in the file name of the newly generated file(s). Files can be saved in either Tab-delimited.txt or Commaseparated Value.csv format. To finish, click Save. Saving a subset of channels from an open signal, and Changing the file format Use the Channels window of the Layout view to save a subset of channels from an open signal. Click the area to the right of the check the boxes next to the numbers of the channels that you want to save; the channel numbers will become highlighted in yellow.

3 Then Choose File > Save Selected Channels As. This new method allows an entire channel or channels of data to be saved and replaces the need to create a selection of an entire view. You can choose to Save the new file in a number of different formats: 8-bit, 16-bit, or 24-bit.aiff or 8-bit, 16-bit, or 24-bit.wav. Choose the file type, then click Save. Batch Channels Export To export a specific subset of channels from a collection of sound files, put the collection of files (or copies of the files) in one directory. Then choose Tools > Batch Export Channels. As the Input Folder, enter the name of the directory containing the collection of files you d like to change, then enter the name of the Output Folder in which you want to store the new files. Choose the channels that you would like to export and click OK. Selectable look & feel, and desktop background color The color and texture of the Raven window (the look and feel ) can be selected so that it mimics the appearance of several standard application types, or retains Raven s unique appearance. Choose Window > Look and Feel, and select Metal, Motif, or Windows. Metal is Raven 1.3 s standard appearance. Choose Window > Background Color to open the Background Color Editor panel and set the color of the main Raven screen area (the desktop) through Swatches, HSB, or RGB color definitions. Beamforming view for multi-channel bearing analysis The beamogram plot represents a range of bearing angles in degrees on the y-axis, and time in seconds on the x-axis. The bearing angles calculated for the source signal over time are plotted. To find the bearing angle with the maximum power for a specific selection in Raven, choose the measurement Max Bearing (not to be confused with Maximum bearing, which is a parameter in the Beamforming Bearing Grid). After opening a multi-channel sound file, choose View > New > Beamogram View or choose the icon from the New View Buttons. Then enter the following information in each of the tabbed pages. Choose OK to apply the configuration and close the Configure Beamogram window. Or choose Apply to preview your parameters without closing the window. Medium Sound speed refers to speed of sound within the medium in which the recording was made, usually either air or water. The speed of sound varies in these media based on a number of parameters, including the temperature and density of the media. However, a useful approximate value for the speed of sound in air is 330 meters/second, and in saltwater a useful approximate value is 1500 meters/ second.

4 Array Enter the X and Y locations in the sensor array. One sensor should be designated as a reference. The other sensors should have coordinates that indicate position (in meters) relative to the reference sensor. Filtering If you would like the signal to be bandpass filtered before the beamformer calculation, enter low and high frequency limits to define the bandwidth that will be passed through the filter. Beamforming Time Grid The Record size is the number of samples of sound over which a beam will be computed. The system then hops by the number of samples given in Hop size and repeats the computation. This process is repeated iteratively for all beams. Normalize channels If the gain imbalance between the recorded channels is large, it may become the main information used in the beamformer computation. Therefore, unless the microphones and recording unit are carefully calibrated to produce a uniform gain, normalizing the signal will be useful. Bearing Grid The Minimum bearing and Maximum bearing values (in degrees) define the range over which the series of individual beams will be calculated. It is generally useful to restrict the range to the directional region most likely to contain the source. The Number of bearings is the number of beams that will be computed. A larger number of beams will usually produce a more accurate measurement. The resolution of the beamformer system is defined by the difference between the Maximum bearing and Minimum bearing, divided by the Number of bearings. Bearing Coordinate System When the Reference bearing is set to zero degrees, the array is set to be perpendicular to the sound source. Altering the reference angle alters the orientation of the array to the sensor for the purposes of the beamformer calculation. The rotation of the Bearing Grid that results from altering the reference angle can be specified as either Counterclockwise or Clockwise. View Channels You can create different subsets of channels to use with the beamformer calculation and compare the results. To alter the Beamogram parameters choose View > Beamogram Configuration. Max Bearing Measurement (beamogram view) The Max Bearing is the bearing measurement corresponding to the bin in the beamogram selection that contains the greatest power. Units: degrees

5 The following Measurements have been added from Canary: Average Power The power in the selection divided by the duration of the selection. Units: db Center Frequency Center Time The amplitude-weighted central time of the selected interval. Units: sec Delta Power Energy The total energy in the selection. Units: joules/m 2 Coming Soon Sound Correlation Detection of target signals within a sound. This will include interactive, batch detection in the realtime recorder, which will allow the recorded to record a specific subset of detections. Additional information about extensibility in Raven, related to both audio devices and detectors. Additional documentation.

Please feel free to download the Demo application software from analogarts.com to help you follow this seminar.

Hello, welcome to Analog Arts spectrum analyzer tutorial. Please feel free to download the Demo application software from analogarts.com to help you follow this seminar. For this presentation, we use a