HT instruments HT157 - Manual (Page 26)

HT155 - HT157
EN - 24
5.2. NOISE ANALYSIS IN 1/1 AND 1/3 OCTAVE BAND (HT157 ONLY)
Further to the statistic analysis, the instrument HT157 allows carrying out accurate
measurements of the noise spectrum by using internal octave-band (1/1) and third-octave-
band (1/3) filters
5.2.1. INITIAL OPERATIONS
1. Turn on the instrument by pressing the “ ” key. The screen for the selection of the
analysis type is shown on the display for approximately 5s (see Fig. 22)
Fig. 22: Initial screens for analysis in 1/1 and 1/3 octave band
2. Use the “ ” or “ ” keys to select the item “1/1 OCT Analyzer (00202)” and press “ ”
to activate the octave band analysis (1/1) or the item “1/3 OCT Analyzer (00303)” and
press “ ” to activate the third-octave band analysis (1/3). The instrument shows the
main menu consisting of 6 icons on the display
3. Select the relevant icon and press “ ” to enter the specific menu:
 List  the instrument shows, in numerical form, the sound pressure level for each
central band frequency in the range 16Hz
16kHz (1/1 analysis) and in the range
12.5Hz
 16kHz (1/3 analysis) and the equivalent levels weighted A, C and Z
 Graph  the instrument shows the histograms of the 1/1 and 1/3 analyses
 Total  the instrument shows the whole of the data of the spectrum analysis
 Data  Section which contains the data of the recordings saved with the instrument
(see §)
 Setup  allows accessing the instrument’s programming menu (see § 4.6)
 Calibrate  section in which it is possible to make the initial calibration by using the
provided portable calibrator HT151 (see § 6.1.3)
4. The indication next to the icon “ :XXX” in the right-hand top part of the display
indicates the number of the group of the datum which can be saved in the instrument’s
memory