Answer to Question #193204 in Electrical Engineering for ahmet

Question

Draw the block diagram of the GM Superheterodin receiver and describe its operation and the 1015 kHz carrier

Find out what value the local oscillator frequency should get to receive the radio channel with frequency.

Answer 1

Signals enter the receiver from the antenna and are applied to the RF amplifier where they are tuned to remove the image signal and also reduce the general level of unwanted signals on other frequencies that are not required.

The signals are then applied to the mixer along with the local oscillator where the wanted signal is converted down to the intermediate frequency. Here significant levels of amplification are applied and the signals are filtered. This filtering selects signals on one channel against those on the next.

Once filtered the next block in the superheterodyne receiver is the demodulator. This could be for amplitude modulation, single

sideband, frequency modulation, or indeed any form of modulation.

The final element in the superheterodyne receiver block diagram is shown as an audio amplifier.

The local oscillator frequency is tunable frequency inside the RX used to translate the RF signal to the IF frequency:

$f_{LO}=f_{RF}+f_{IF}$

where $f_{RF}$ is Radio Frequency, the center frequency the signal is broadcast on.

$f_{IF}$ is Intermediate Frequency, fixed frequency inside the RX. The RF signal is downconverted to this frequency. 

Carrier frequency is the frequency of a carrier wave, that is modulated to transmit signals.