This paper investigates modulation schemes for ultrasonic intra-body networks. State-of-the-art Implanted Medical Devices (IMD) are mostly based on On-Off Keying (OOK) which is the simplest type of modulation. However, MATLAB simulations depict the higher power efficiency of Binary Phase-Shift Keying (BPSK) over OOK and other binary modulation techniques. Moreover, at equal Bit Error Rate (BER) and emitted signal power, the higher power efficiency eventually results in a gain of achievable depth that is quantified in water. At last, alternatives to power-hungry Phased-Locked Loop (PLL)-based demodulation circuits are explored as their complex structure generally thwarts the use of BPSK modulation.