What's the IFG?

IFG is short for Intermediate Frequency Gain and is an important setting item for radio. The intermediate frequency here is not named according to the middle, high and low-frequency band, but according to its position and function in the circuit. So how do you understand the IFG here?

Intermediate Frequency usually refers to a signal obtained by frequency conversion of high-frequency signals in the superheterodyne receiver Circuit. It is relative to baseband and RF signals. The intermediate frequency can have one or more levels. It is a bridge between baseband and RF. The intermediate frequency is not a fixed frequency point or frequency band. For example, the intermediate frequency signal of the short- and medium-wave radio is 465KHz, and the intermediate frequency of the FM radio is 10.7MHZ.

Why convert high-frequency signals into intermediate-frequency signals? We can know from the comparison of the work of superheterodyne and direct receiver that when the high-frequency signal received by the antenna is not converted into an intermediate frequency signal, the gain tuning between all levels of frequency cannot be unified, and the receiving sensitivity will be greatly reduced. Therefore, in order to enable the amplifier to work stably and reduce interference, the general receiver must change the high-frequency signal into an intermediate frequency signal.