在电子基础理论中我们常常碰到分贝(■b)这个名词,这是一个用来表示声音和电信号在传输过程中功率增加(增■)和减少(损耗)的计算单位。它与我们常用的许多单位具有不同的性质。例如常用的长度单位“尺”,当用它来测量不同物体长度时,一尺所表示的长度都是相等的。但分贝却不是这样,例如当电路的功率损耗都是1分贝时,如果原来的功率为100毫瓦,那么降低1分贝就是减少约20毫瓦,如果原来是10毫瓦,那么就减少约2毫瓦。可见1分贝只表示原来值的20%。即分贝表示两个功率的比值,但是它不是直接表示这个比值,而是通过一种特殊的方法——对数,来表示的。 In electronic basic theory, we often encounter the term decibel (■ b), which is a unit of measure used to indicate the power (increase) and decrease (loss) of sound and electrical signals during transmission. It has many different properties than many of our commonly used units. For example, the commonly used length unit “ruler”, when used to measure the length of different objects, the length of a foot said are equal. However, this is not the case for decibels. For example, if the power loss of the circuit is 1 decibel, reducing the decibel by 1 decibel would reduce by about 20 milliwatts if the original power was 100 milliwatts, or about 2 if it was 10 milliwatts Milliwatts. Visible 1 decibel represents only 20% of the original value. That is, the decibel represents the ratio of two power, but it does not directly represent the ratio, but by a special method - logarithm.