Wireless communications a)The following signal represents a 4-bit amplitude modulated signal (10102). What is the carrier frequency? b)You want to transmit the capital letter J over a free space optical link. Assume the link uses a laser which operates at a wavelength of 1200 nm and generates a sinusoidal carrier frequency of 1 kHz, a constant bit time of 4 msec (e. g. each bit sent takes 4 msec to send), and the system sends the most significant bit first. Plot the amplitude versus time for an on-off keyed (OOK) signal, normalizing the amplitude to 1. (Hin