Signal theory for SONET STM-1

The authors discuss a signal theory approach to SONET fundamental operations: (1) multiplexing of payloads, section path overheads into a SONET structure; (ii) scrambling; and (iii) conversion into a line signal. The CCITT recommendations are taken as reference, but the formulation is sufficiently general to include the operations STS of US standards. In particular, the following sequence of operations is considered: (a) multiplexing of a C-4 into a VC-4, (b) multiplexing VC-4 into a AU-4 with general pointer settlement, (c) multiplexing of an AU-4 into STM-1 (synchronous transport module-level 1). It is shown that this sequence (including scrambler) is equivalent to a linear FIR (finite impulse response) filter. As an example of application of the modules, spectral analysis after the line conversion of an STM-1 frame sequence with a specific payload is carried out