Multidimensional channel coding

DETAILED DESCRIPTION Transmitter 10 of FIG.
1 includes a scrambler 104, encoder 110 and modulator 121.
Scrambler 104, in particular, receives a stream of binary data from a data source 101 which may be, for example, a digital computer.
Scrambler 104 pseudo-randomizes the data to prevent concentrations of energy across the spectrum of the bandpass signal ultimately to be generated.
The output of scrambler 104 is a serial bit stream which is applied to encoder 110.
The latter is comprised of a serial-to-parallel converter 111, differential encoder 114 and symbol generator 117.
Serial-to-parallel converter 111 converts the bit stream received from scrambler 104 into a sequence of p-bit signal indications, or words, with the bits of each word being provided in parallel form on leads 112.
The words on leads 112 are applied to differential encoder 114, the output of which is another sequence of p-bit signal indications, or words, (described more fully below), with the bits of each word being provided in parallel form on leads 115.
The words on leads 115 are applied to symbol generator 117.
The latter responds by extending to modulator 121 over cable 118 representations of n-dimensional data symbols to be transmitted over a communication channel 15.
The values of the words on leads 115 are such that the values of successive words on leads 112 are represented by the vector difference between successive pairs of symbols on cable 118.
(This approach enables the system to recover from so-called phase hits in the transmission channel.
) Modulator 121 responds to the data symbols provided from symbol generator 117 to generate a double sideband-quadrature carrier signal of the form ##EQU1## where T is the so-called baud interval, m is an index which advances at the baud rate 1/T, g(t) is a real function representing a so-called Nyquist pulse and .
omega.
.
sub.
c is a selected radian carrier frequency.
The portion of signal s(t) which extends over each baud interval is referred to herein as a double sideband-quadrature carrier pulse