Why local oscillator frequency is higher than signal frequency?
Why local oscillator frequency is higher than signal frequency?
The reason a higher frequency is commonly chosen in a Super heterodyning receiver, is to leave more distance between the difference or intermediate frequency and the other two frequencies so that the IF signal can be more easily passed through a filter and attenuate the the original two signals.
What is local oscillator frequency?
In electronics, a local oscillator (LO) is an electronic oscillator used with a mixer to change the frequency of a signal. This frequency conversion process, also called heterodyning, produces the sum and difference frequencies from the frequency of the local oscillator and frequency of the input signal.
Why local oscillators are used?
A local oscillator is an electronic oscillator used to generate a signal normally for the purpose of converting a signal of interest to a different frequency using a mixer.
What is the frequency of a local oscillator in superheterodyne?
This corresponds to a frequency of 5260 kHz. Note that the oscillator output is not a sine wave, but contains significant harmonic distortion, which is quite common.
Why if frequency 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.
What is the main function of local oscillator in case of superheterodyne receiver?
A local oscillator provides the mixing frequency; it is usually a variable frequency oscillator which is used to tune the receiver to different stations.
What is the main function of a local oscillator in case of a superheterodyne?
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.
Why is it that the RF section and the local oscillator are ganged tuned?
There is a fixed difference in frequency between the local oscillator and the RF amplifier at all times. This difference in frequency is the IF. This fixed difference and ganged tuning ensures a constant IF over the frequency range of the receiver.
What is the difference between RF and IF?
RF to IF conversion is achieved using a RF device called Down-converter. Heterodyne and homodyne receiver architectures are used to convert modulated RF signal to IF signal. Superheterodyne uses 10.7MHz as first IF and 470KHz as second IF….RF vs IF.
| Type of application | Intermediate Frequency value |
|---|---|
| Radar | 30MHz |
What is the difference between heterodyne and superheterodyne?
Superheterodyne is the made with two different words. When a frequency is generated beyond the human hearing then it is called “super” sonic. “Heterodyne” means mixing of two different frequencies so it is called superheterodyne or often we call “superhet”. It is used as a receiver in radio or microwave.
What is the purpose of IF frequency?
The use of an IF simplifies the design of tunable receivers and reduces the number of components that must be compatible with high frequencies. IF architectures simplify the design of bandpass filters because the reduced center frequency results in a lower Q-factor requirement.
What is the main difference between heterodyne and homodyne receiver?
In radio technology, the distinction is not the source of the local oscillator, but the frequency used. In heterodyne detection, the local oscillator is frequency-shifted, while in homodyne detection it has the same frequency as the radiation to be detected. See direct conversion receiver.