Question

Consider the Voyager spacecraft, transmit frequency 8.4 GHz, transmitter power P_T= 21.3 W, transmitting antenna gain G_T is 6.5 x 10⁴ W/W at a distance of 6.8 x 10¹¹m from Jupiter to Earth. Both the Voyager and earth based antennas are parabolic dishes whose cross sectional area can be assumed equal to the effective antenna aperture.

a) Calculate the Voyager antenna gain (dB) and diameter

b) Calculate the receiver antenna gain (dB) with a dish diameter of 64m.

c) Calculate the received power (dBm).

d) The comm link requires a receive signal to noise ratio of 10dB to achieve a 115.2 kbps data rate with a bit error rate of 2x10^-5. Calculate the receiver noise N_o=kTB where k is Boltzmann’s constant, T is the receiver equivalent noise temperature of 28.5 deg K and B is the bandwidth.Assuming BPSK modulation with 1 bps/Hz the bandwidth is equal to the data rate. What is the SNR margin (dB)?

Answer 1