Multifrequency binary measurement using frequency shift keyed symbols

A new approach to designing signals for multifrequency binary testing (MBT) depends on digital modulation, which uses shift keyed symbols. This allows a variety of ways in which the binary energy may be concentrated in arrays of dominant harmonics. Phase shift keyed (PSK) signals have been previously shown to give narrowband detail with a high spectral resolution. Frequency shift keyed (FSK) symbols with the aid of harmonic arrays are designed to obtain wideband frequency information. The power is concentrated in a lower and a higher harmonic array whose spacing may be adjusted by a wideband factor. New designs, which have both wideband and narrowband detail, are obtained by combining PSK and FSK symbols