Spread-sprectrum techniques are widely used in state-of-the-art communication systems for suppression of interference. In this paper we will establish the characteristics required for signal-processing devices used in such systems. Typical spread-spectrum waveforms will be described to emphasize those characteristics which lead to good system performance. The synchronization problem will be reviewed to show that this is often the most difficult aspect of a communication system design and strongly influences the choice of devices. The performance of any device in a system will reflect some features of the device which are undesirable. Spurious responses can cause errors in detection or demodulation circuitry. A limited dynamic range for a signal-processing device might have the effect of lowering the apparent interference rejection of the system.