Configuring the SVAN 912A to measure Infrasound
Setting the instrument to measure subsonic sound
To measure this infra-sound the SVAN 912A is an ideal instrument.
You configure the instrument as follows:
- Insert the microphone
- Press Power
- Select the Aux. Functions (Use the arrows)
- Press Enter
- Select more... (Use the arrows)
- Press Enter
- Select Mic. Pol.
- Use the left right arrows and set it to 200V
- Press ESC ESC
- Select the ANALYSER MODE (Use the arrows)
- Press Enter
- Press The FUNC key
- Use the left right arrows and Set FUNCTION to 1/3 Oct.
- Press INPUT and ensure the FILT is set to Lin
- Press ESC
- Note that if you wish to save this Setup
- Press SECOND FUNCTION > SETUP
- Down arrow to NAME:
- Press Enter
- Use the arrow keys & The Enter key to set an appropriate
name. The ENTER keys jumps characters and the arrow keys change
characters. The space is in the bottom right hand corner.
- Press ESC when the name has been correctly set
- Arrow up to SAVE OP
- Press ENTER (The display will indicate the setup has been saved)
- Press ESC to return to the SPECTRUM display
- Press Start
- The up and down arrows can be used to set the sensitivity of the display.
- Use the Left and Right Arrows and so that F:20Hz is set
- The part of the display you are interested in is to the
left of the vertical line this is the infra-sound. This is the sound
which cannot be heard but can be 'perceived' and as such could be
interpreted as supernatural!
Configuring the SVAN 912AE to log a subsonic spectrum
The SVAN 912AE can be used to generate a spectrum waterfall plot.
- Download the SVAN software from the SVAN website SVANTEK software
- Install the software and set the coms port and communications
rate appropriately (Select Aux Functions then RS-232 Interface. Set the
Comms rate as per the SVANTEK software 38400,N,1 these settings can be
found in the software under Svan>RS232 settings. The communications
port you are using is also specified here)
- Check the Microphone polarity is switched on
- Select AUX FUNCTIONS
- Select more..
- Select MIC.POL. press the right arrow and set to 200V
- Press ESC ESC to return to the main menu
- Calibrate the SVAN 912AE.
- Attach calibrator and switch it on
- Select CALIBRATION from the main menu
- Press FUNC
- Set CALIBR to ON
- Set CAL_TYPE to Measure
- Set LEVEL to 94dB (Check the cal sheet with the calibrator)
- Set INP_ATTEN to 0dB
- Set INT.TIME to 1s
- Press INPUT
- Set INPUT to Microphone
- Set RANGE to 90dB
- Set Filter to Lin
- Set A.RANGE to ON
- Press Start to begin the calibation
- Press Stop after a couple of seconds
- The meter should display the calibration factor
- Press Enter to save the calibration factor
- Press ESC to exit to the main menu...
- We will now check the calibration
- Press METER MODE
- Press Start
- The meter should display 94dB
- The meter is now calibrated
- Remove the calibrator and turn it off
- Press ESC to return to the main menu
- Configure the SVAN 912AE buffer size
- Select Aux. Functions
- Select More...
- Select BUF.SIZE
- Use the right arrow and set the Buffer Size to 400kB
- Press ESC ESC to return to the main menu
- Configure the Analyzer Mode
- Select Analyzer Mode
- Press the FUNC key
- Set FUNCTION to Spectrum
- Set S.LINES to 120 (in this case)
- Set A.REPEAT to ON
- Set WINDOW to Hanning (in this case)
- Set AVERAGE to Linear
- Set AVER.No to 2048 (The largest number available Use the 2nd function key for a course change in the function)
- Press INPUT
- Set INPUT to Microphone
- Set RANGE to 70dB (in this case)
- Set BAND to 177Hz (in this case)
- Set FILTER to Lin (in this case)
- Press DISPLAY
- Set DISPLAY to Spectrum
- Set Y-SCALE' to Log.70dB (in this case)
- Set S.PLOT to Lines
- Set Scanning to Off
- Press INPUT twice to edit the Trigger setup
- Set TRIGGER to Int +
- Set LEVEL to 0%
- Set DELAY to 10sec (Use the 2nd function key for a course change in the function)
- Start Logging
- When the Start key is pressed the spectrum will be logged
every 10 seconds. As each spectrum uses around 120 bytes the time
duration of the logging is around 9hrs
- When the logging has been completed you need to save the buffer. Press Stop to finish logging
- Save the logged data
- Press FILE
- Set FILE_OP to Save_Buf
- Set FILENAME to a unique name (Pressing right arrow will generally achieve this)
- Press ENTER whn the cursor is on FILE_OP
- Download the data to the SvanPC software and display the waterfall plot
- Click Svan>Svan FIles
- Click Refresh
- Click the appropriate saved filename
- Click Open
- Click View>Spectra
- Click View>Options
- Select multi element
- Click OK
- The [s] represent 10 second intervals
- Click Tools>Unit Change to change from Linear to Log vertical scaling
- You can also select the number of spectra displayed. Or the data can be configured for download to a spreadsheet.
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