A method is outlined for determining the relationships between the grade of performance, or message error rate, of a radio communication system and the system parameters. Results are presented in the form of design equations and system-design curves. The system parameters and variables considered are the following definable and measurable factors: signal-to-noise ratios, carrier signal power level, message load, receiver noise figure, etc. These factors are used with the design curve scales as normalizing factors in order to yield quantitative results.