我们看到体脂检测、高频射频电路、或者超声波检测都选择用正弦波，而不是三角波、...

QWE4562009

我们看到体脂检测、高频射频电路、或者超声波检测都选择用正弦波，而不是三角波、方波或者锯齿波？是从哪些因素考虑的？
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超級狗

菜英文可能幫不上你！

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Sine waves are great for driving ultrasonic transducers. The resulting current waveform, more or less, will have pristine harmonic contents which will be great for analysis and feedback control. You also therefore avoid driving other harmonics which will create heat and cause unwanted oscillatory behavior. Sine waves can also be properly and easily amplified (or reduced) by a transformer in order to deliver maximum power to the transducer. Digital amplitude control is also a common feature of sine wave drive circuits.

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So why would be drive our transducer with a square wave, which by its very nature consists of many harmonics and can be quite rigid with regards to amplitude control?

There are two aspects of square waves which are awesome:

(1) Square waves drive signals are easy to generate.

(2) The half bridge and full bridge drivers used to generate square wave drive signal have an extremely low output impedance. This means that the drive voltage will not change at all due to changes in impedance of the transducer during operation. You cannot say that for almost all sine wave drive circuits, where such impedance change can cause instability.

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超級狗

沒往生的話，我們再聯絡！

QWE4562009

超級狗 发表于 2021-12-9 08:04
菜英文可能幫不上你！
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. n7 p0 u% [% kSine waves are great for driving ultrasonic transducers. The resulting cur ...

你的意思是啥？用正弦波和方波都是可以的？

bazhonglei

从频谱角度分析，三角波、方波或者锯齿波驱动会产生谐波（干扰信号）和震荡波不利于分析，并且谐波电流会使系统功耗增加。三角波、方波或者锯齿波放大、采集会失真。