UNIT – 4 PROCESS SIGNAL MODULATION AND DEMODULATION TECHNIQUES
Pulse Digital Modulation Pulse Code Modulation
• PCM is a digital pulse modulation system. Its output is in the coded digital form.
• In PCM, the available range of signal voltages is divided into samples and each sample is represented by a binary number.
• PCM transmitter is shown in fig. in fig., the message signal x(t) [fig. (a)] passes through low pass filter to limit the maximum frequency of the signal and is given to sample and hold circuit and then to
quantizer.
• Quantizer reduces the effect of noise and generates quantized PAM [fig. (d)] and it will be the input of encoder (A to D converter). • The encoder generates the output in digital form and is converted
into a stream of pulses by the parallel to serial converter.
Pulse Digital Modulation Pulse Code Modulation
• PCM is a digital pulse modulation system. Its output is in the coded digital form.
• In PCM, the available range of signal voltages is divided into samples and each sample is represented by a binary number.
• PCM transmitter is shown in fig. in fig., the message signal x(t) [fig. (a)] passes through low pass filter to limit the maximum frequency of the signal and is given to sample and hold circuit and then to
quantizer.
• Quantizer reduces the effect of noise and generates quantized PAM [fig. (d)] and it will be the input of encoder (A to D converter). • The encoder generates the output in digital form and is converted
into a stream of pulses by the parallel to serial converter.
Pulse Digital Modulation Pulse Code Modulation
• PCM is a digital pulse modulation system. Its output is in the coded digital form.
• In PCM, the available range of signal voltages is divided into samples and each sample is represented by a binary number.
• PCM transmitter is shown in fig. in fig., the message signal x(t) [fig. (a)] passes through low pass filter to limit the maximum frequency of the signal and is given to sample and hold circuit and then to
quantizer.
• Quantizer reduces the effect of noise and generates quantized PAM [fig. (d)] and it will be the input of encoder (A to D converter). • The encoder generates the output in digital form and is converted
into a stream of pulses by the parallel to serial converter.
Pulse Digital Modulation Pulse Code Modulation
• PCM is a digital pulse modulation system. Its output is in the coded digital form.
• In PCM, the available range of signal voltages is divided into samples and each sample is represented by a binary number.
• PCM transmitter is shown in fig. in fig., the message signal x(t) [fig. (a)] passes through low pass filter to limit the maximum frequency of the signal and is given to sample and hold circuit and then to
quantizer.
• Quantizer reduces the effect of noise and generates quantized PAM [fig. (d)] and it will be the input of encoder (A to D converter).
• The encoder generates the output in digital form and is converted into a stream of pulses by the parallel to serial converter.
Pulse Digital Modulation Pulse Code Modulation
• PCM is a digital pulse modulation system. Its output is in the coded digital form.
• In PCM, the available range of signal voltages is divided into samples and each sample is represented by a binary number.
• PCM transmitter is shown in fig. in fig., the message signal x(t) [fig. (a)] passes through low pass filter to limit the maximum frequency of the signal and is given to sample and hold circuit and then to
quantizer.
• Quantizer reduces the effect of noise and generates quantized PAM [fig. (d)] and it will be the input of encoder (A to D converter). • The encoder generates the output in digital form and is converted
into a stream of pulses by the parallel to serial converter.
Pulse Digital Modulation Pulse Code Modulation
• PCM is a digital pulse modulation system. Its output is in the coded digital form.
• In PCM, the available range of signal voltages is divided into samples and each sample is represented by a binary number.
• PCM transmitter is shown in fig. in fig., the message signal x(t) [fig. (a)] passes through low pass filter to limit the maximum frequency of the signal and is given to sample and hold circuit and then to
quantizer.
• Quantizer reduces the effect of noise and generates quantized PAM [fig. (d)] and it will be the input of encoder (A to D converter). • The encoder generates the output in digital form and is converted
into a stream of pulses by the parallel to serial converter.
• PCM consists of 3 steps to digitize an analog signal:
1 Sampling
2 Quantization
Advantages:
• Very high noise immunity.
• It is possible to store the PCM signal (because it is digital in nature). Disadvantages:
• Large bandwidth. • Complex circuitry.
