Assignment No. 03
Semester: Fall 2013
Total Marks: 15
Due Date: 20/01/2014
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Question 1: (10 Marks)
a) Assume that a sports channel is using FM (frequency modulation) for broadcasting its transmission. You are required to calculate the bandwidth of broadcasted signal (modulated) in KHz for each of the following signals:
b) Suppose a radio channel is using AM (Amplitude modulation) for broadcasting its transmission. You are required to calculate the bandwidth of broadcasted signal in KHz for each of the following signals:
Question 2: (5 Marks)
Radio waves transmission utilizes five different types of propagation. You are required to identify at least one application (that uses the particular propagation) for each of the given propagation types.
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Assignment 03 file in doc
For low radio frequencies, terrestrial antennas radiate electromagnetic waves that travel along the surface of the Earth as if in a waveguide. The attenuation of surface waves increases with distance, ground resistance, and transmitted frequency. Attenuation is lower over seawater, which has high conductivity, than over dry land, which has low conductivity. At frequencies below 3 megahertz, surface waves can propagate over very large distances. Ranges of 100 km (about 60 miles) at 3 megahertz to 10,000 km (6,000 miles) at 1 kilohertz are not uncommon.
The service area from a television (TV) or frequency modulated (FM) radio transmitter extends to just beyond the optical horizon, at which point signals start to rapidly reduce in strength. Viewers living in such a "deep fringe" reception area will notice that during certain conditions, weak signals normally masked by noise increase in signal strength to allow quality reception. Such conditions are related to the current state of the troposphere.
The ionosphere is a region of the upper atmosphere, from about 85 km (53 mi) to 600 km (370 mi) altitude, and includes thethermosphere and parts of the mesosphere and exosphere. It is distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth.
Line of Sight:Line of sight (LoS) is a type of propagation that can transmit and receive data only where transmit and receive stations are in view of each other without any sort of an obstacle between them. FM radio, microwave and satellite transmission are examples of line-of-sight communication.
Space propogation: The radio waves having high frequencies are basically called as space waves. These waves have the ability to propagate through atmosphere, from transmitter antenna to receiver antenna. These waves can travel directly or can travel after reflecting from earth’s surface to the troposphere surface of earth. So, it is also called as Tropospherical Propagation. In the diagram of medium wave propagation, c shows the space wave propagation. Basically the technique of space wave propagation is used in bands having very high frequencies. E.g. V.H.F. band, U.H.F band.
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Part (b): 18 KHz Answer (m i right or wrong???)
BW of FM = 2 (b + 1 ) B
Beta is a factor depends on modulation technique with common value of "4".
BM of FM = 2(1+4)B
BM of FM = 10*Bandwidth of modulation signal (in our hanouts)
AM requires the twice the BW of orignal signal so,
BW of AM = 3*6 = 18 khz (mera ans 3 hi nkla ha)
Answer ko nkalne ke units b match krna ho ge.
1Hz = 0.001kHz
1kHz = 1000Hz
The frequency f in kilohertz (kHz) is equal to the frequency f in hertz (Hz) divided by 1000:
f(kHz) = f(Hz) / 1000
Convert 300 hertz to kilohertz:
f(kHz) = 300Hz / 1000 = 0.3kHz
modulation signal with frequencies of 4000 to 7000 Hz = f(Hz)= (7000 Hz - 4000 Hz) = 3000Hz
when we convert Hertz to kilohertz
f(kHz) = 3000 / 1000
f(kHz) = 3 KHz