Designing multifrequency ternary test signals using frequency shift keyed modulation

This paper introduces a set of multifrequency ternary sequence (MTS) signals which has not previously appeared in the published literature. They are MTS octave signals, which are designed by frequency shift keyed (FSK) modulation so that two separate parts of a frequency response are examined by one test signal. One of these signals is a new five octave FSK MTS signal which is described by a total of 64 symbols. This is half the number of symbols required by the equivalent five octave Van den Bos Multifrequency Binary Sequence (MBS) signal. There are 4, 5, 6, etc. octave FSK MTS in the set all of which have one important advantage over an equivalent MBS signal. Even when described by a symmetrical measurement code, the switch-on transient is normally eliminated during the system identification of most systems. If it is not, the measurement code may be rearranged in an asymmetrical form to further minimize the switch-on transient during the first period of the signal. This means that two sets of accurate frequency estimates are obtained immediately after the first period of these novel signals. During this first period, when these signals are generated with a symmetrical code, a useful multifrequency data pattern may also be obtained. It may be used to condition monitor two separate parts of the frequency response of a system. The advantages of the five octave FSK MTS test signal are illustrated with the aid of the data measurement toolbox using a simulated process with three lags.