Quadrature modulation systems are used in satellite communication. I and Q are two channels which are represented in modulated signals. One of the schemes of Quadrature modulation is offset Quadrature Phase Shift Keying. Quadrature Phase Shift Keying produces the phase ambiguity in carrier recovery process which can be eliminated with OQPSK.Also OQPSK ensures high speed transmission in optical Networks. Due to more requirements of the radio channels, spectral effective modulations are intended to diminish spectral overload of communication systems. One such methods of modulation is offset QPSK. Forward Error Correction (FEC) is proposed in this paper for the OQPSK transmitter. Convolutional encoders are used in FEC for the process of encoding. FEC is technique that introduces redundancy to allow correction of error. Forward error correction is achieved by using convolution method. FEC technique is used in audio and video applications.The convolutional encoder with half the rate of input data stream and constraint length k=3 & k=7 are designed and corresponding source codes are generated. The source codes for the two encoders are programmed using MATLAB and VHDL. The outputs of MATLAB source code is used for comparison analysis of VHDL source code outputs. MATLAB is mainly used to check the functionality of the encoder. The convolution encoders are generated using MATLAB and VHDL code and their outputs are verified.
