I called Knowles today and it was hilarious.

littleshrimp

I called Knowles today and it was hilarious. [Copy link]

I looked up Knowles online and it seems to be a well-known company. I took a fancy to their ultrasonic microphone SPU0410LR5H. I looked up ultrasonic on the official website and found this model. I also saw it for sale on Mouser. The frequency range in Mouser's parameters is 100Hz~80KHz. It is ultrasonic, but when I opened the data sheet, there was no information that the frequency can be greater than 20KHz. So I wanted to call the manufacturer to ask about their contact information in China. They have quite a few headquarters in Shanghai. The first call to Shanghai was "The number you dialed is out of service." Next is Beijing. "Please dial the extension number directly to check the number. Please dial zero. After dialing 0, it will prompt that the extension you dialed is not answered. Please dial other extensions or the switchboard will serve you later." Then it hangs up. Hanging up is understandable. According to the writing of the program, it is probably entering an infinite loop. Then I prepared to dial Shenzhen manually. I saw that the phone number was 7 digits. It was definitely not going to work. Finally, there was only Suzhou left. Let's try it. A beautiful girl answered the call. She spoke very politely. When I said I wanted to consult about the microphone problem, she interrupted me in a hurry and said, "Stop, I don't understand this." She said, "I'm just an answerer. You need to contact our sales. We don't answer business on this phone." I said, how should the business be contacted? She said, "I don't know either." I said, "What is your phone used for?" She said, "We are transferring the call. Tell me who you want to contact and I will transfer it to you." I said, "How can you transfer the call if you don't even have a business number?" She said, "I don't know." I said, "Can you help me check it?" Then she asked me how much I purchased, my contact information, company information, etc., and finally asked me to wait for a call

littleshrimp

I couldn't download the data sheet from the official website, so I went to Mouser and found that the data sheet I downloaded from the SPU0410LR5H-QB page was SPU0410LR5H-1. Later, I found the data sheet of SPU0410LR5H-QB on digikey, which had information about ultrasonic waves.

topwon

Attenuation at 80KHz is -12dB (referenced to 1KHz)?

topwon

Oh, the above version may be old (it seems to be from 2011). Looking at the specification book from 2013, 80KHz is about -4dB.

cruelfox

This is a microphone for audio frequency applications, not designed for ultrasonic applications. Although it responds to frequencies above 20kHz (the self-oscillation frequency of a silicon microphone is >10kHz, so it is not surprising that it can sense ultrasonic waves), the design optimization and testing requirements are all within the audio range, so there is a reason why the frequency response curve above 20kHz is not given. The frequency response is even only given to 10kHz, because the rise from 10k - 20kHz is too much and it doesn't look good.

littleshrimp

cruelfox posted on 2019-5-28 11:07 This is a microphone for audio frequency applications, not designed for ultrasonic applications. Although it responds to frequencies above 20kHz (the self-oscillation frequency of silicon microphones is >10kHz, ...

This is the information on SPU0410LR5H-QB that I found on digikey. Can you help me take a look?

littleshrimp

topwon posted on 2019-5-28 10:45 Oh, the above version may be old (it seems to be from 2011). I saw the specification book in 2013, and 80KHz is about -4dB.

The official website information has not been downloaded. I downloaded it from digikey, July 2018

cruelfox

Knowles, not Knowles, not the real estate market. If you want to use it for ultrasonic recording and ultrasonic testing, this can be used. But it cannot be used for calibration, because the characteristics of MEMS determine that the response above 10kHz will not be flat.

littleshrimp

cruelfox posted on 2019-5-28 20:46 Loushi, not Loushi, not Loushi. If you want to use it for ultrasonic recording and ultrasonic testing, this can be used. But it cannot be used for calibration, because...

Loushi is the Chinese name of their official website. The simplified Chinese on their website seems to be automatically translated by translation software

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