mesure de l’impédance, de la fréquence et de la sensibilité en décibels (dB)

[Mhafsi]

Bonjour à tous,

J’ai un nouveau projet qui consiste à concevoir un banc de test pour valider le fonctionnement d’un capteur ultrason transmetteur et d’un capteur ultrason récepteur (de même famille) par la mesure de l’impédance, de la fréquence et de la sensibilité en décibels (dB) du capteur sous test. J’ai consulté le catalogue des produits NI, mais je n’arrive pas à identifier les équipements de test nécessaires.

Sachant que :

• Pour le capteur ultrason transmetteur : à f = 40 kHz, SPL = 120 dB.
• 
• Pour le capteur ultrason récepteur : à f = 40 kHz, sensibilité = -63 dB.
• 

Comment puis-je identifier, parmi les produits NI, les équipements qui répondent à nos besoins ?

[santo_13]

https://www.ni.com/en-us/shop/model/pxie-4468.html would be your best solution from NI

[Mhafsi]

Thank you for your repley.

Could you please provide the selection criteria for the NI 4468 module compared to other similar modules?

knowing that the conditions for testing the ultrasonic sensor are as follows:

1-Generation of a 40 kHz (sine wave, 10 Vrms).

2-Detection of the acoustic signal at a distance of 30 cm between the ultrasonic sensor and the acquisition module(considering the signal is very weak).

In this case, is it necessary to use a signal amplification module?

3-Signal acquisition and calculation of sensitivity in dB.

The sound pressure level (SPL) measured for the receiver should be -63 dB (±3 dB) at 40 kHz, while the transmitter sensitivity is 120 dB (±3 dB).

Which NI modules would you recommend to meet these test requirements?

Thank you in advance for your assistance.

[santo_13]

A few basics: NI hardware generates or acquires analog voltage, and the transducer takes care of bridging the electrical and acoustic domains.

To generate/acquire 40kHz signal, by Nyquist theorem, you need at least 80kHz sampling rate, this narrows down your options to only a few.

Next, your requirement is to generate 10V signal, almost every DSA module can deal with 10V.

To translate between the dB SPL to equivalent voltage rms, use the transducer's sensitivity.

As per your table, the tx generates 120 +/-3 dB SPL when exicited with 40kHz 10Vrms signal.

On the other hand, the rx generates -63 +/-3 dB per Pascal where 0dB is 10V per Pascal

https://www.analog.com/en/resources/analog-dialogue/articles/understanding-microphone-sensitivity.ht...

Now substitute the Output AREF with 10V and Sensitivity dBV with -63, calculate Sensitivity V/Pa to 14,125.375Vrms/Pascal

Using the Vrms/pascal scaling factor, you can convert the signal from rx to equivalent Pascal or even SPL.