NTi Audio Minilyzer ML1 - Manual (Page 38)

38
Measurement Functions
Zoom (Y-Axis): The scaling of the spectrum’s Y-axis (sensitivity) is
fixed and may be adjusted manually.
• Select the zoom (Y-axis) field and press the enter key.
• Use the up/down keys to scroll the displayed level along the Y-
axis and the left/right keys zoom out/in the Y-axis, e.g. alter the
resolution of the division.
Time Constant: The time constant corresponds to the integration time
of the 1/3 rd octave recording. It may be set to five value: 0.2 / 0.5 /
1.0 / 2.0 / 5.0 seconds. A lower time constant results in a quicker,
more ‘nervous' display, whilst a higher time constant ‘averages’
more samples, thus providing a more stable spectrum.
Bargraph: Below the spectrum, the fullband input RMS level (20 Hz
- 20 kHz) is indicated by a bargraph without auto ranging. Select the
different indication ranges by moving the cursor to the left or right
arrow below RNGE and press enter. The available ranges are:
• -120 to -20 dBu, residual noise of ML1 < -120dBu (<1μV), enables
measurement of low signal levels
• -100 to 0 dBu
• -80 to +20 dBu, please note in this range the residual noise of
ML1 is gained by 20 dBu.
1/3 rd Octave SPL
The 1/3 rd OCTAVE SPL screen shows the signal frequency spectrum
of the acoustic signal, divided into 31 bands.
Fig 3.20 1/3 rd Octave SPL Screen
Arrow
Mode
Arrow Readout
Bargraph of Level SPL
Scaling
of Y-Axis Zoom
(Y-Axis)
Time
Constant
1/3rd Octave
Spectrum
Run/Pause