The purpose of a communication system is to carry information from a source to a destination through a reliable medium. In practice, the issues arise in transmitting the baseband signal.
The limitations of baseband transmission can be overcome using modulation. It is a technique in which the baseband signal is translated from lower frequency on to the higher frequency of the carrier wave. In analogue communications, the modulation techniques are categorised into linear and nonlinear modulation schemes. They can be given as:
Linear Modulation schemes
– Amplitude modulation (AM),
– Double sideband suppressed carrier amplitude modulation (DSBSC-AM),
– Single sideband suppressed carrier amplitude modulation (SSBC-AM)
– Vestigial sideband modulation (VSB)
Nonlinear Modulation schemes
– Frequency modulation (FM)
– Phase modulation (PM)
Each student is required to select any two from linear modulation schemes and one from nonlinear modulation schemes and perform the following tasks:
- Derive expression for modulated signal () for each modulation technique when the baseband signal is () = mc2m and the carrier signal is () = c2c
- For each modulation technique () is transmitted through Additive white Gaussian noise channel with power spectral density n = 1×10-11 -1 and bandwidth of 5.5KHz. The channel has attenuation of 50dB. Compute the SNR as function of transmitted power of modulated signal, when the signal is detected using coherent detection.
- Plot the SNR with respect to the transmitted power of the received modulated signal for each modulation scheme. Compare the SNR results and comment on the performance of the respective modulation techniques
You are required to submit a report with 1600 words.
The report should include:
A description of the overall purpose of each component in the design and why it is required. Note: for this section you will need to use your background research on communication channel impairments and techniques.