In a satellite, there exist various communication subsystem like Telecommand, Telemetry and Payload data transfer. Depending on the requirements of a particular system, different modulation techniques are being used. In general, M-PSK modulation techniques are preferable as they are power and bandwidth efficient. The paper presents the digital implementation QPSK & 8-PSK modulators for satellite communication. The modulators are realized using the concept of Direct Digital Frequency Synthesis (DDFS). The use of look up table and COrdinate Rotation Digital Computer (CORDIC) algorithm is explained in details with their comparison on the basis of spectral purity and hardware requirements. The paper describes different methods of implementations of QPSK and 8-PSK modulator with comparison in terms of hardware requirement. The design of modulators are first developed, simulated and optimized on the software tool and then coded in VHDL for hardware realization. The designs are tested on Xilinx platform.