Symbolic codes allow a simple description of binary test signals for the identification of control systems. These symbolic descriptions of digital shift keyed modulation using compact binary codes are highlighted as the basis for designing new multifrequency binary sequence (MBS) test signals. Their energy may be concentrated in frequency arrays which measure specified spectral information. Phase shift keyed (PSK) MBS signals are designed with a zoom attribute to identify narrowband frequency information with a high spectral resolution. Frequency shift keyed (FSK) MBS use an extended range attribute to evaluate wideband frequency information. The application of these test signals is illustrated by two examples.