When expressing the resistance tolerance error and the tolerance of the frequency characteristic range of the sensor, it may be expressed as a ratio from a reference value such as В±5 The decibel in this case is usually considered as voltage ratio. ', which is suitable for evaluation of sensoryДecibels and percentages (percent,%) also represent ratios, mutual conversion of numbers is possible. Weber-Fechner law ' The perceived intensity is proportional to the logarithm of the stimulus.

The calculation can be easily performed because multiplication and division can be replaced by addition and subtraction. When characteristic evaluation is performed, such as a multistage amplifier or a plurality of transmission systems,.When expressing large numbers such as the gain of the amplifier, using decibels can express it with fewer digits.So, there are many cases that it is written as 'dB в—‹ в—‹' instead of simply 'dB'.ДЄs you can see in the explanations so far, there are many advantages of using decibels. In summary, it can be said that the absolute level value represents the physical quantity itself, considering dB as a unit. The decibel itself is not a unit of SI unit systems, but in the acoustics field decibel is used as a quantity conforming to the unit. Even in this case, the decibel value expresses the absolute value (sound pressure value) in the same way. However, the reference value defined by the sound pressure level often used in the acoustics field is not 1. In the example so far, the reference value was 1, so calculation was simple. If the reference value is defined as 1 m/s 2, then 5 m/s 2 means about 14 dBm/s 2. The exact same can be said for other physical quantity.Д¬onsider, for example, an example of vibration acceleration. This absolute level value is used to express the voltage range value of the input part in the FFT Analyzer (see Table 5). When the reference value of voltage ratio is defined as 1 V, an arbitrary voltage value can be expressed by a decibel value. From here, the level and decibel are explained as almost the same meaning.Д¬onsidering an example of expressing a voltage value is shown below. Generally, the magnitude of the physical quantity expressed in decibels in the field of electricity and sound (vibration) is called 'level (unit dB)'. If the reference value (the denominator of the ratio) is defined as a fixed physical quantity, the decibel value in that case can be easily converted as the absolute value of the physical quantity, so it can be regarded as an absolute level value. That is, even if the decibel value is negative, the antilogarithm value itself is not a negative number, but only the electric power ratio (or voltage ratio) is smaller than 1.Дecibel, as also defined, represents the ratio of the two quantities, which simply means the relative level value. This is the logarithmic property itself as described above. When the antilogarithm value is less than 1, the dB value is negative. As shown in Table 4 above, when the antilogarithm value is greater than 1, the dB value is a positive value.

Decibel meaning