HT instruments HT157 - Manual (Page 29)

HT155 - HT157
EN - 27
Fig. 25: Graphic screen of 1/1 spectrum analysis
9. The screen shows the histogram of the sound pressure level associated to the
frequency spectrum whose center is reported on the x-axis, further to the indications of
the frequency weightings A, C, and Z. The minimum and maximum values on the y-axis
are determined by the measuring range selection
10. Move the cursor to the line at the bottom of the x-axis and use the “ ” or “ ” keys to
select the spectrum frequencies. Observe the movement of a “music note” at the top of
the graph. Use the same keys to dynamically modify the measuring range.
11. For the remaining functions, please refer to the numerical display
12. With cursor flashing on the “
” icon, press the “ ” or “ ” keys to access the
“Total” display of the measure (or select the “Total” icon in the main menu). The
instrument displays the following screen, relevant to the “Linst” item:
Fig. 26: Total section screen 1/1 spectrum analysis – Instant values
2. The initial part shows the system date/time and the measuring range which can be
modified by using the “ ” or “ ” keys. In the five central lines, the instrument
provides the instant values of the following sound pressure levels in frequency
weightings A, C, Z and with time constants Fast, Slow, Impulse: LAFp, LCFp, LZFp,
LASp, LCSp, LZSp, LAIp, LCIp, LZIp. Lines 7 and 8 show, in graphic bars, the instant
values of the quantities: LAFinst, LASinst, LAIinst, LCFinst, LCSinst, LCIinst,
LZFinst, LZSinst, LZIinst
3. Select the “ ” icon and confirm with “ ” to save the data in the instrument’s
memory