two frequencies instead of one frequency where the transmitter and the receiver have a look up table to represent every 4 bits by two frequencies of the 7 frequencies used further at the receiver the frequencies transmitted are known by obtaining the power spectral density psd from which the receiver determines the 2 frequencies transmitted in a 2 of 7 message then from the look up table found in the receiver the data that has been transmitted is determined as illustrated in fig4 a mat lab code is used to calculate and draw the bit error rate ber for different values of baud rate the results of this simulation describe the relation between bit error rate ber and baud rate for a 2 of 7 system also mat lab code is used to calculate the bit error rate ber for different values of the signal to noise ratio snr fig5 is the result of this simulation on the 2 of 7 system fig6 shows a transmitter block diagram 100 including the steps used to manipulate the 2 of 7 multiple orthogonal locked frequencies narrow band frequency shift keying mary nbfsk wherein a first block indicates reading data from the file to be transmitted a second block 104 indicates making the source coding of the data to decrease the amount of data required to be transmitted then a channel coding block 106 is provided for channel enhancement further a fourth block 108 is indicative of taking every successive 4 bits and assign 2 frequencies from the available 7 frequencies to represent the 4 digits using a look up table.