Page
33
A Appendix
-
Measurement Modes
A.2
Relative Logarithmic
The reading is displayed in dB as the ratio of a defined reference. To define a
value, enter the menu item Reference (
one unit
: reference value is set to 1,
CW
: reference value is set to actual reading,
manual reference
: manual entry
of reference value,
1.000mW
: reference value is set to 1mW, reading is provid-
ed in dBm units). If the
Relative (Log)
measuring mode is entered, the db value
according to the following equation is displayed together with the actual read-
ing:
where
X
displayed quantity in dB or dBm
x
actual reading of the instrument
x
ref
reference value
A.3
Pulse Energy
A.3.1
Principle
Pulse energy can be defined as the integral of the input signal over time (which
equates to the pulse area).
X
exposure
x(t)
measured quantity as a function of time
T
flash duration time
The P
-
9710
-
2 can measure pulse energy for pulse lengths down to 1µs, even
though the internal Analog to Digital Converter (ADC) can sample the input
signal only every 100µs. To perform this measurement task, the shape of the
input signal is changed. A short high pulse is transformed into a long low
pulse. But the key point is that the area equal that to the energy of the pulse is
preserved.
ref
x
x
X
10
lg
10
T
dt
t
x
X
)
(
