基于定置噪声的汽车转速测量新方法及其实现

A new method for measuring the rotary speed of a car's engine based on the spacing measurement of its noise and its implementation

不同于传统汽车转速测量方法,提出了通过非接触传声器测量汽车定置噪声从而计算汽车发动机转速的新方法.给出了方法的计算模型.设计了以高速、低功耗、浮点型数字信号处理器DSP为核心的双CPU新型硬件结构,且结合DSP汇编语言与C语言开发了相应的算法与软件,验证了所提出的方法.开发了基于测量汽车定置噪声的新型数字式汽车转速检测仪器,其转速测量范围30～8000r/min,转速测量误差±10r/min,噪声测量范围30～130dB,分辨率0.1dB,准确度优于±0.5dB.

Differing from the conventional method, the new rotary speed measuring method is measuring the noise of the engine in definite distance by a microphone and then calculating the rotary speed of it. The model for calculating the rotary speed from the noise is established. The hardware scheme is designed, in which two CPUs are used. One is for digital signal processing and the other is MCU for man-machine interface. The corresponding algorithm and software are developed using DSP assembly language and C language, and therefore the new method is proved. A rotary speed measuring instrument based on this method is also developed. It can measure the rotary speed of 30～8 000 r/min, the measuring error is ±10 r/min; its noise measuring range is 30~130 dB, its noise resolution is 0.1 dB, and its accuracy is higher than ±0.5 dB.