1. In a sending station operable in a communication system to send data upon a communication channel susceptible to fading, an improvement of apparatus for placing the data in a form to facilitate communication thereof upon the communication channel, said apparatus comprising: an encoder coupled to receive first values representative of the data to be communicated upon the communication channel, said encoder for encoding the first value representative of the data into encoded form, the encoded form forming a codeword of a recursive, systematic space-time code, and the codeword complying with an equal eigenvalue criterion.