When using a chart recorder the following settings can be used as an initial guideline: -
Paper speed (or X-axis travel) 0.5cm/sec.
Sensitivity (or Y-axis travel) 200mV/cm (using 180mm paper)
The following procedure can then be used: -
1 Connect the chart recorder (or X-Y plotter) to the sound level meter.
2 With the filters switched OUT measure the sound level .
3 Keeping the meter on the same ‘range’ switch the meter to the AUTO mode. Press
RESET and the 31.5Hz LED should be lit.
4 Start the chart recorder moving and when ready press the START/STOP button
once. A downward ‘stroke’ of recorders pen will indicate where the start was, and
also each change of frequency.
5 When the filter has reached the top (16kHz) frequency it will remain there. To
repeat the procedure depress the RESET button in order to start from 31.5Hz fre
quency again. Pressing the START-STOP button during the stepping procedure
will STOP the filter on its current centre frequency, pressing the button once more
will START the stepping once more. The START-STOP button therefore acts as an
effective ‘pause’ facility.
Note
The horizontal (or X-axis) is logarithmic frequency in Hz, or kHz corresponding to the ten fil-
ter centre frequencies as indicated on the front panel of the sound level meter. The vertical
scale (or Y-axis) is in dB’s and therefore linear. Some calibration and setting up of the chart
recorder will be necessary if direct readings are to be taken from the rulings on the chart re-
corder paper.
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Содержание GA112
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