# Current Calculation For Single-Tone AM Signal

Communication
May 22, 2020

## Current Calculation For Single-Tone AM Signal

In AM, it is generally more convenient to measure the AM transmitter current than the power.

In this case, the modulation index may be calculated from the values of unmodulated and modulated currents in the AM transmitter.

### Mathematical Expression

Let I_{c }be the r.m.s. value of the carrier or unmodulated current and I_{t} be the r.m.s. value of the total or modulated current of an AM transmitter.

Let R be the antenna resistance through which these currents flow.

Now, we know that for a single-tone modulation the power relation is expressed as :

……………….. (1)

where P_{t} = total or modulated power

P_{c} = carrier or unmodulated power

m_{a} = modulation index

Now, equation (1) can be written as :