A family of practical data-transmission systems, whose design is motivated by a desire to reduce the required energy per bit (for a specified noise power density) while operating in a well-defined part of the frequency spectrum, is described. The blocks of

information bits that are periodically fed to the transmitter are encoded into equal energy waveforms whose design is based upon the use of truncated

impulse response networks, together with an

-dimensional unit hypersphere code. The same waveform generation equipment is used for matched filtering at the receiver terminal. This design approach leads to equipment that performs well in the presence of impulse noise as well as Gaussian noise.