AM Radio Communication System Simulation in Proteus

AM Radio Communication System Simulation in Proteus

 Here AM radio communication system simulation is illustrated in Proteus. The radio communication system is designed using the MC1496 balanced modulator demodulator. In the demonstration, a message tone signal and AM modulated and sent from the transmitter. At the receiver the received AM signal is demodulated and original message tone signal is recovered. The received signal is sent LM358 audio amplifier which then goes into a speaker. One could also test with actual audio signal but due to simulation limitation it is not shown here.

The following shows the circuit diagram of the AM transmitter and AM Receiver.

AM Radio Communication System Simulation in Proteus

The AM transmitter is build using the Single Supply MC1496 AM modulator. It can also be build using two power supply as illustrated in AM modulator using MC1496 modulator. The AM receiver is build using the AM Detector Demodulator with MC1496.
The AM transmitter circuit diagram is shown below.
AM Transmitter

 In the AM transmitter, information signal or modulating signal is applied at Vs port. This input signal is connected to pin 1 and 4 of the modulator. The carrier signal is applied at the Vc port which is connected to  pin 8 and 10. The output appears at pin 6 and 12. The carrier signal amplitude is 60mV and the frequency is 500KHz. Here for faster simulation purpose 40KHz carrier signal is used. The message signal amplitude is around 300mV and the frequency is 1KHz. The resistors connected to the input and output ports are for biasing the internal differential amplifier circuitry inside the modulator IC.

The AM receiver circuit diagram is shown below.
AM receiver
 At the receiver the local oscillator signal of 500KHz(here for faster simulation 40KHz is used) and amplitude 300mV is applied to the port VLO. The carrier signal frequency should be same as the transmit RF carrier frequency used at the RF transmitter. The received AM signal via the RF antenna is applied to the pin1 via 0.1uF coupling capacitor. The AM detector/demodulator mixes the input AM signal with the local oscillator carrier signal. The output which appears at pin 12 of the demodulator is the message signal plus some sideband. The message signal plus some noise passes from the demodulator output to a low pass filter which is made of R24 resistor of 1K and 5nF capacitor C12. This low pass filter has cutoff frequency of around 31KHz which lets the audio signal to pass through and block other frequency components. After the filter, the signal then is coupled using the coupling capacitor C13 into the LM368 audio amplifier circuit. The 10K potentiometer is used to adjust the volume of the audio signal. Then from the  LM358 amplifier circuit the signal is fed into the speaker. 
 The following shows the transmitted message signal, the carrier signal, the transmitted AM signal and the recovered message signal.

The following video demonstration the simulation of AM Radio Communication System in Proteus.


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