Answer Happy

1. Say whether each of the following statements is True or False and give a full and complete justification. Use diagrams wherever needed. No partial credit will be given for answers without sufficient explanation. (a) M-ary PAM is used to increase the rate of communications in comparison to binary communications, but at the expense of more bandwidth. (b) In theory, a minimum of 4 GPS satellites are needed to determine the location on the surface of the earth if all clocks are fully synchronized. (c) The Nyquist sampling rate for the product of the two signals sinc(100nt) and sinc-(1200nt) is 2600 Hz. (d) It is possible to let several co-located users use the same frequency band and transmit at the same time without having interference. (e) Nyquist second criterion for controlled ISI controls ISI by using pulses that do not interfere with the neighboring pulses at the sampling instants. (f) A Zero-forcing equalizer (ZFE) with 3 taps can be used to eliminate the ISI with 2 left and 2 right neighboring pulses without any residual ISI. (g) M-ary FSK requires M times the bandwidth of binary FSK, but its power does not depend on M. (h) If a direct sequence spread spectrum (DSSS) transmitter with a QAM modulator uses a 10-stage shift register for its PN sequence generator, then to jam this transmitter, a jammer needs 10 times the power needed to jam the same QAM signal without DSSS and cause the same degradation.