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Good lab manual on analog and digital
Typology: Study notes
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Department of ECE
Prepared By
Mr. P.R.RATNA RAJU.K, M.Tech, Asst. Professor Department of ECE, MITS, Madanapalle
Part A (Analog Communication Lab):
Part B (Digital Communication Lab):
Mr. P R Ratna Raju.K & Mr. D Balakrishna Reddy Dr A.R.Reddy Faculty In-Charge Head of the Department
EXP.NO DATE Experiment Name Page No Remarks 1 2 3 4 5 6 7 8 9
Fig 3: Carrier Generator Theory: Modulation is defined as the process by which some characteristics of a carrier signal is varied in accordance with a modulating signal. The base band signal is referred to as the modulating signal and the output of the modulation process is called as the modulation signal. Amplitude modulation is defined as the process in which is the amplitude of the carrier wave is varied about a means values linearly with the base band signal. The envelope of the modulating wave has the same shape as the base band signal provided the following two requirements are satisfied (1). the carrier frequency fc must be much greater then the highest frequency components fm of the message signal m (t) i.e. fc >> fm (2) The modulation index must be less than unity. if the modulation index is greater than unity, the carrier wave becomes over modulated
Procedure:
1 Switch on the trainer and check the O/P of carrier generator on oscilloscope.
in A.F. signal.
modulated waveform.
provided at A.F. input.
following formulas.
Tabular Column:
S. No Modulator O/P Demodulator O/P
Fm (Hz)
Vm (V)
Vmax (V)
Vmin (V)
m Fo (Hz)
Fig 1: Circuit Diagram for Frequency Modulator
Fig 2 : Circuit for Frequncy Demodulator
PROCEDURE:
without any A.F. input.
(At AF input).
adjust the amplitude of the AF signal to get clear frequency modulated wave form.
the modulated waveform.
Tabular Column:
Vc= , Fc= ,Vm=
Sl No
Fm (KHz)
Tmax(μsec) Tmin(μsec) Fmax (KHZ)
Fmin (KHZ)
β B.W (KHZ)
Demod Vo (V)
3. Characteristics of Mixer
Aim: To observe the characteristics of a Frequency Mixer and to measure its conversion
gain..
Apparatus Required:
Theory: The mixer is a nonlinear device having two sets of input terminals and one set of output terminals. Mixer will have several frequencies present in its output, including the difference between the two input frequencies and other harmonic components
Circuit Diagram:
Fig 1: Mixer Circuit Diagram
the transistor.
maximum value at a particular frequency. Calculate conversion gain.
Conversion gain = (O/P Voltage)/ (Base signal voltage)
Sample readings:
S.No Fx (KHz)
Fy (KHz)
Vx (V)
Vy (V)
Fo (KHz)
Output voltage(V)
Gain(dB)
De-Emphasis:
Procedure:
Sample readings:
Table1: Pre-emphasis Vi = 20mV
S.No Frequency (KHz)
Output voltage (V)
Gain (dB)
**1.
5.**
Table2: de-emphasis Vi = 5V
S.No Frequency (KHz)
Output voltage (V)
Gain (dB)
**1.
6.**
MODEL GRAPH
Result: