Assume that there is a phone in every home on earth. If these were to transmit simultaneously over one transmission line by using frequency-division multiplexing, what is the minimum bandwidth required? Could a single optical beam carry this multiplexed signal? (Assume that 10 billion homes need to transmit.)

-2 Three amplifiers defined by T₁ = 350 K with G₂i = 3.0, T2 = 330 K with G₁2 = 2.6, and T₂3 = 300 K with G₁,3 = 2.2, can be cascaded in any order.What is the best order from a low-noise standpoint?

Compute and plot the photon energy, in eV, for wavelengths between 1260 and 1675 nm.

P-2.23 Complex exponentials obey a simple rule for the operation of time shifting: the complex amplitude experiences a phase change. Consider the complex signal z(t) = Zei10nt where Z = 7e0.3x. (a) The time-shifted version of z(t) can be represented as a new complex exponential with complex amplitude W. Thus, z(t-ta) =w(t)== Wei10nt, Determine the complex amplitude W when ta = 0.24 s.

P-2.18 Determine the values of the parameters {o, q,A} in the equations below. \text { (b) } 10 \cos (9 \mathrm{t}-\pi / 3)=\mathrm{A} \cos (\omega \mathrm{t}-\pi / 2)+5 \cos (\omega \mathrm{t}+\varphi)

P-3.14 The two-sided spectrum of a signal x(t) is given in the following table, but some of the values are not yetknown. (a) If x(t) is a real signal, use symmetry properties of the spectrum to determine the numerical values of the parameters: X-1, X2, 001, and 002.

How many voice channels can be modulated onto a carrier at wavelength 1.06 µm? Assume a system bandwidth equal to 1% of the carrier frequency.