ATIS T1.TR.04
Mathematical Modeling of DS1, DS1A, DS1C, DS3 and DS4NA Waveshapes
| Organization: | ATIS |
| Publication Date: | 1 October 1990 |
| Status: | active |
| Page Count: | 74 |
scope:
INTRODUCTION
To facilitate equipment compatibility, it is necessary to identify the pulse of the generated signal as well as the signal present at the Cross-Connect Frame for a given transmission medium. The Source equipment and the receiver equipment are designed to generate or accept the predetermined waveforms. The First though Third Electrical Hierarchical Levels utilize an AMI2 (Alternate Mark Inversion) type bit sequence of ones and zeros. While the Fourth Electrical Hierarchical Level utilizes a CMI (Coded Mark Inversion) type bit sequence of ones and zeros as its generated signal.
The AMI-type bit sequence involves coding zeros as absence of voltage amplitude and alternation positive and negative maximum voltage amplitudes of a square wave to depict the one signal. The zero pulse is not affected by its transmission along a medium as initially it is a zero voltage pulse and cannot be attenuated or experience phase distortion, this document is specifically concerned with the defined signal pulses of the all ones, Bipolar, AMI bit sequence.
The CMI-type bit sequence used at the DS4NA, 139.264 Mb/s, North American Fourth Electrical Hierarchical Level requires tow test pattern waveforms. Either the all ones or the zeros waveform may be transmitted along a given medium. Ideally, the all zeros waveform is generated as a square wave with a fundamental frequency of 139.264 MHz. The all ones wave form is also generated as a square wave, but with a fundamental frequency of 69.632 MHz.
The defined nominal signals identify one pulse of the all ones or all zeros Binary CMI bit sequence, and the Bipolar AMI bit sequence. However, the individual all ones or all zeros signal pulses are symmetric and identical to one another, so by defining one pulse, the entire waveform may be defined. The nominal signal pulses presented in this document address the issues of frequency, amplitude, and waveform skew characteristics.
2 Bold print indicates that the definition of a word or further information concerning a word's context is included in the glossary.
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