QUESTION 1

a) What are the possible digital-to-analog modulation techniques?

I. ASK (amplitude-shift keying)II. FSK (frequency-shift keying)

III. PSK (phase-shift keying)

b) What is the aim of multiplexing?

I. Multiplexing refers to the sharing of a channel such as a telephone channel by users cofined to a local site.

II. Multiplexing is the process of transmitting several messages simultaneously on the same circuit or channel.

III. Is a process to combine multiple signal to transmit it over a single channel or media.

IV. Combines several low-speed signal for transmission over a single high-speed connection.

V.  To share an expensive resource. 

QUESTION 2

a) What is the channel capacity for teleprinter channel with 300 Hz bandwidth and a signal-to-noise ratio of 3 dB?

I = ?

B = 300 Hz

S/N = 3 / 10

= 0.3

*10^0.3 = 1.995

I = 3.32B log10 (1 + S/N)

= (3.32)(300) log10 (1 + 1.995)

= 474.5 bps // 0.474 bps

b) Given a channel with an intended capacity of 20Mbps and a bandwidth of 3 Mhz what would be the SNR to archieve this capacity?

QUESTION 3

b) For a binary data : 11010010, sketch the output waveform of aI. ASK modulator

II. FSK modulatorIII. PSK modulator

Assume the carrier is a sinusoidal signal.

Baseband Data 1 1 0 1 0 0 1 0

ASK modulated signal

FSK modulated signal

PSK modulated signal