A local oscillator (LO) is an electronic oscillator that is used to change the frequency of a signal in electronics. This process, known as heterodyning, generates sum and difference frequencies from the local oscillator’s frequency and the input signal’s frequency. This helps a radio receiver to perform better, as it processes a fixed frequency. Often, in many receivers, the functions of the local oscillator and the mixer are combined in a single stage called a converter, which reduces space, cost, and power consumption by combining the functions in one active device.
The local oscillator produces a sinusoidal signal at a frequency that allows the receiver to produce the correct resulting frequency or intermediate frequency (IF) for further amplification and conversion to audio detection. In a single conversion superheterodyne receiver, there is a local oscillator that generates beat frequencies by superposition or mixing, which can be the sum or difference of two frequencies. The local oscillator is adjustable to match the increase or decrease in the receiver frequency.
The local oscillator is an important device used in several electronics fields. It is usually inserted to match the increase or decrease in the receiver frequency and is useful to insert a message into a high frequency carrier using Amplitude Modulation (AM).
Frequently Asked Questions (FAQ)
What is the function of a local oscillator?
The local oscillator is an oscillator that generates a frequency to mix with another frequency in a heterodyne process. This creates a frequency difference between the two that can be more easily processed and amplified by the subsequent audio amplifier stages.
What is heterodyning?
Heterodyning is the process of combining two frequencies in a non-linear electrical circuit to produce sum and difference frequencies. In electronics, heterodyning is used mainly to change the frequency of a signal.
What is the difference between a local oscillator and a master oscillator?
A local oscillator generates a frequency used to mix with another frequency in a heterodyne process, while a master oscillator generates a stable frequency reference for other oscillators and circuits to synchronize with.
Final Thoughts
The local oscillator plays an essential function in several electronics applications, and it is useful in a wide range of applications that require the change of frequency. By generating a frequency that can be mixed with another frequency in a heterodyne process, it can produce sum and difference frequencies that are more easily processed and amplified by subsequent stages in the circuit.
