The Application of Tech Codes in LEO/MEO Spread Spectrum System
Fab Cercas, AA Albuquerque, M. Tomlinson · International Symposium on Information Theory and its Applications · 1994
A new class of codes named TCH is proposed which can significantly help to reduce the interference in LEO/MEO systems for personal communications as in VSAT systems. These codes of binary length can be used to implement a correlation receiver using a bank of correlators very efficiently and with a low level of complexity. The near optimum -correlation properties of TCH sequences and their near flat spectra makes them suitable for use in CDMA spread spectrum systems, where they can be used as PN sequences. The derivation of the codes is explained and their performance is compared with that of the traditional half-rate convolution encoding with soft-decision Viterbi decoding and with a similar BCH code in a concatenated scheme. The magnitude spectrum of a typical TCH sequence is also plotted as well as its periodic auto-correlation.