Match List 1 with List 2

List 1	List 2
(a) DPSK	(i) Non coherent  detector
(b) AM	(ii) Ratio detector
(c) FM	(iii) Coherent detector
(d) DSB – SC	(iv) Rectifier Dectector

Choose the correct answer from the options given below:

(1) (a) - (i), (b) - (iv), (c) - (ii), (d) - (iii)

(2) (a) - (iii), (b) - (i), (c) - (iv), (d) - (ii)

(3) (a) - (ii), (b) - (iii), (c) - (i), (d) - (iv)

(4) (a) - (iv), (b) - (ii), (c) - (iii), (d) - (i)

DPSK Demodulator:

In the DPSK demodulator, the phase of the reversed bit is compared with the phase of the previous bit. Following is the block diagram of the DPSK demodulator.

• From the above figure, it is evident that the balanced modulator is given the DPSK signal along with 1-bit delay input. That signal is made to confine to lower frequencies with the help of LPF.
• Then it is passed to a shaper circuit, which is a comparator or a Schmitt trigger circuit, to recover the original binary data as the output.
• The local oscillator is not present in the DPSK receiver. So, it is also called a “Noncoherent detector”

AM Receiver:

The following demodulators (detectors) are used for demodulating AM waves.

• Square law demodulator
• Envelope detector

​Square Law Demodulator:

Envelope Detector:

This looks like a rectifier. So, this can be named as “Rectifier detector”.

FM Demodulator:

The main types of FM demodulator found in broadcast receivers, radio communication systems two-way radios or walkie talkies / handheld radios, etc, are outlined below:

• Slope detection
• Ratio detector
• Foster Seeley FM demodulator
• PLL demodulator
• Quadrature detector

DSB – SC Demodulator: Coherent detector is used for demodulating DSB-SC waves.

The block diagram of a coherent detector is as shown below: