välitaajuudesta

Välitaajuus, in Finnish, translates to intermediate frequency or IF. It is a concept primarily used in radio receivers and signal processing. In superheterodyne receivers, the incoming radio frequency signal is mixed with a locally generated frequency, called the local oscillator frequency, to produce a signal at a fixed, lower frequency. This lower frequency is the intermediate frequency.

The purpose of down-converting the received signal to an intermediate frequency is to simplify the subsequent amplification and filtering stages. By converting all incoming signals to a common IF, the receiver can use fixed-tuned filters and amplifiers, which are easier to design and manufacture with consistent performance. This allows for more precise tuning and better selectivity, enabling the receiver to distinguish between closely spaced radio channels.

The specific value of the intermediate frequency varies depending on the receiver design, but common values include 455 kHz for AM receivers and 10.7 MHz for FM receivers. After amplification and filtering at the intermediate frequency, the signal is then demodulated to recover the original information, such as audio. The concept of intermediate frequency is fundamental to the operation of most modern radio communication systems.