Why is 455 kHz?

Before getting into the why, 455 kHz is the intermediate frequency for an AM broadcast band radio receiver. The local oscillator tunes to 455 kHz higher than the radio signal of interest, and the mixer output difference between the LO and the rf is filtered and amplified at 455 kHz.

Why do we use intermediate frequency?

The main reason for using an intermediate frequency is to improve frequency selectivity. In communication circuits, a very common task is to separate out, or extract, signals or components of a signal that are close together in frequency.

Why local oscillator frequency is higher?

The local oscillator frequency (f0) is made greater than signal frequency (Fs) in radio receiver: Hence, the 2.2:1 ratio required for the local oscillator operating above signal frequency is well within range whereas the other system has a frequency ratio of 14:1 whose capacitance are not practically available.

Why do we need superheterodyne receiver?

The superheterodyne receiver offers superior sensitivity, frequency stability and selectivity. Compared with the tuned radio frequency receiver (TRF) design, superhets offer better stability because a tuneable oscillator is more easily realized than a tuneable amplifier.

What is Radio alignment?

Alignment usually means to turn various built-in adjustable components to put the equipment back to factory specs. This is necessary because as some electronic components age, they change in value over time. That can and does cause reduced performance of the radio.

What are the factors to be considered in selecting intermediate frequency?

Abstract: The selection of an intermediate frequency for a super-heterodyne receiver involves consideration of the signal frequency, the tuning range, the pass-band width, the minimizing of spurious responses, regeneration stability, and frequency stability.

Why local oscillator is used in superheterodyne receiver?

The superheterodyne receiver uses one or more mixers and local oscillators to convert the received signal channel to another frequency band for more convenient filtering and amplification.

What is the significance of the RF amplifier?

The RF amplifier increases the signal by enabling it to tune over the desired range of input frequencies. An RF amplifier is actually a tuned amplifier that enables the input signal of broadcast or transmitted information to control an output signal.