Radio receiver working explanation with block diagram
Radio, Transistor or Television works on the same principle. First we will see working of radio in this post. In radio broadcasting station voice is converted in to audio signal with the help of microphone. The output signal from microphone is in the order of millivolt, so audio signal is amplified with the help of audio amplifier. All radio station works at different frequencies allotted to them. A oscillator circuit is used to generate radio frequency voltage known as carrier frequency . The amplified audio signal is then mixed with carrier frequency to produce modulated radio frequency. This process is known as amplitude modulation. This modulated radio frequency are then amplified in RF power amplifier and given to antenna which propagates the radio frequency to space surrounding earth.
The Radio used the opposite of this process. A block diagram of radio is given below
First RF signal is received with the help of Arial/antenna. Then this signal is amplified in RF amplifier stage. A local oscillator is used to generate high frequency signal. Then in mixer stage both RF signal and local oscillator signal is mixed to produce intermediate frequency signal (IF). IF signal is amplified in IF amplifier stage. This IF signal is sent to demodulator stage which converts IF signal to audio signal. This audio signal is sent to audio amplifier stage through volume control. Final amplified signal is sent to speaker which convert audio signal to sound.This is all in short. To catch a particular frequency from Arial a coil in parallel with capacitor is used known as parallel tuned circuit. The property of tuned circuit is that they produce highest impedance for resonant frequency. This property makes them suitable to use in radio frequency selection circuit. Similar tuned circuit is used in local oscillator to produce selected radio frequency. The local oscillator coil frequency is 455 kHz more than radio frequency from antenna coil. when two frequencies mixed in mixer stage they produces their difference frequency 455 kHz as IF frequency. The capacitor connected in parallel with antenna coil and oscillator coil are variable gang capacitor. When adjusted by spindle both capacitor value changes simultaneously. This makes possible that both antenna coil frequency and oscillator coil frequency changes simultaneously and their difference remain constant 455 kHz IF frequency. This makes possible to change different station by changing the capacitor value. While changing band both antenna and oscillator coils are changed with the help of band switch. When coils changed frequency band is also changed and radio can be tuned for other band stations. For each band it need two coil one antenna coil and one oscillator coil. The number of coils is twice the number of bands.
Radio, Transistor or Television works on the same principle. First we will see working of radio in this post. In radio broadcasting station voice is converted in to audio signal with the help of microphone. The output signal from microphone is in the order of millivolt, so audio signal is amplified with the help of audio amplifier. All radio station works at different frequencies allotted to them. A oscillator circuit is used to generate radio frequency voltage known as carrier frequency . The amplified audio signal is then mixed with carrier frequency to produce modulated radio frequency. This process is known as amplitude modulation. This modulated radio frequency are then amplified in RF power amplifier and given to antenna which propagates the radio frequency to space surrounding earth.
The Radio used the opposite of this process. A block diagram of radio is given below
First RF signal is received with the help of Arial/antenna. Then this signal is amplified in RF amplifier stage. A local oscillator is used to generate high frequency signal. Then in mixer stage both RF signal and local oscillator signal is mixed to produce intermediate frequency signal (IF). IF signal is amplified in IF amplifier stage. This IF signal is sent to demodulator stage which converts IF signal to audio signal. This audio signal is sent to audio amplifier stage through volume control. Final amplified signal is sent to speaker which convert audio signal to sound.This is all in short. To catch a particular frequency from Arial a coil in parallel with capacitor is used known as parallel tuned circuit. The property of tuned circuit is that they produce highest impedance for resonant frequency. This property makes them suitable to use in radio frequency selection circuit. Similar tuned circuit is used in local oscillator to produce selected radio frequency. The local oscillator coil frequency is 455 kHz more than radio frequency from antenna coil. when two frequencies mixed in mixer stage they produces their difference frequency 455 kHz as IF frequency. The capacitor connected in parallel with antenna coil and oscillator coil are variable gang capacitor. When adjusted by spindle both capacitor value changes simultaneously. This makes possible that both antenna coil frequency and oscillator coil frequency changes simultaneously and their difference remain constant 455 kHz IF frequency. This makes possible to change different station by changing the capacitor value. While changing band both antenna and oscillator coils are changed with the help of band switch. When coils changed frequency band is also changed and radio can be tuned for other band stations. For each band it need two coil one antenna coil and one oscillator coil. The number of coils is twice the number of bands.
Great sir! Please post a local home made circuit for radio transmitter and reciever capturing a single frequency and calculations of inductance and capacitance to design tuning circuit to capture that radio frequency
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