Unit of Measurement of Signal Strength in PPI, A-Scope and B-Scope

We are often asked how the strength of the reflected signal is displayed in the PPI, A-Scope of B-Scope. Actually this value depends on the transceiver card and the involved amplifiers. A typical value to depict the signal strength is Voltage (V). The relative difference between several amplitude values is important. Therefore, dB is the second suitable unit of measurement

In our scopes the user can choose between displaying the amplitude values in Volts (V) or decibel (dB). The decibel (symbol: dB) is a relative unit of measurement corresponding to one tenth of a bel (B). It is used to express the ratio of one value of a power or field quantity to another, on a logarithmic scale, the logarithmic quantity being called the power level or field level, respectively. Two signals whose levels differ by one decibel have a power ratio of 101/10 (approximately 1.25893) and an amplitude (field quantity) ratio of 10​1⁄20 (1.12202).