Datasheet
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S15E.pdf
08.10.31
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Electrical Characteristics
1. Sound Pressure Characteristics
Sound pressure level (S.P.L.) is unit indicating the
volume of sound and is expressed by the following
formula.
S.P.L.=20log
P
(dB)
Po
where “P” is Sensor sound pressure (Pa) and “Po” is
reference sound pressure (20µPa).
Fig.6 shows a sound pressure measuring circuit.
2. Sencitivity Characteristics
F.C.
30cm
U.S.
S.C.M.
OSC.
Anechoic Room
Amp.
Fig. 6 Sound Pressure Measuring Circuit
3. Radiation
U.S. : Ultrasonic Sensor
S.C.M. : Standard Capacitor Microphone (Brüel & Kjær 4135)
Amp. : Amplifier (Brüel & Kjær 2610)
Input Voltage
: 10Vrms, Sine wave
F.C. : Frequency Counter 0dB
=
20µPa
Sensitivity is the unit indicating the sound receiving
level and is expressed by the following formula.
Sensitivity=20log
S
(dB)
So
where “S” is Sensor voltage (V) and “So” is reference
sound pressure (V/Pa) .
Fig.7 shows a sensitivity measuring circuit. The 3.9kΩ
resistor connected with the electrode terminal of the
sensor is used to avoid the influence of outside noise.
The ultrasonic sensor is installed on a table. Then, the
relationship between angle and sound pressure (sensi-
tivity) is measured.
In order to express radiation precisely, the angle in
which the sound pressure (sensitivity) level attenuates
by 6dB compared with the front is called the half atten-
uation angle with an expression of θ
1/2
.
30cm
Sp
U.S.
S.C.M.
OSC.
Amp.
R
L
F.C.
Anechoic Room
Fig. 7 Sensitivity Measuring Circuit
RL :3.9kΩ
U.S. : Ultrasonic Sensor
S.C.M. : Standard Capacitor Microphone (Brüel & Kjær 4135)
Amp. : Amplifier (Brüel & Kjær 2610)
OSC. : Oscillator
Sp. : Tweeter
F.C. : Frequency Counter 0dB=10V/Pa