Method and arrangement for coding binary signals and modulating a carrier signal
First Claim
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1. A method for transmitting a bit sequence by modulating a carrier signal to sequentially assume one of a plurality of discrete signal values comprising the steps of:
- subdividing the predetermined bit sequence into successive groups each containing r sequential bits,expanding each r bit group into a group of r+1 bits by a sequential coding process utilizing four internal states,selecting one out of 2r+1 discrete carrier signal values as a function of each r+1 expanded bit group, the selection being made so that 2r-1 carrier signal values correspond to each transition from one internal state of the coding process to one of two possible follower states and that the 2r-1 carrier signal values have a larger minimum distance from each other than the absolute minimum distance within the complete set of discrete carrier signal values, andtransmitting the selected discrete carrier signal values in sequence.
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Abstract
A method and structure for converting a sequence of binary digits into a sequence of discrete signal values, e.g., phase values, of a modulated carrier signal for data transmission. By introducing additional redundant signal values and coding information in a state-dependent sequential manner, enlarged minimum Euclidian distance between possible signal value sequences is achieved which results in a reduced error probability when maximum-likelihood decoding is applied in the receiver.
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4 Claims
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1. A method for transmitting a bit sequence by modulating a carrier signal to sequentially assume one of a plurality of discrete signal values comprising the steps of:
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subdividing the predetermined bit sequence into successive groups each containing r sequential bits, expanding each r bit group into a group of r+1 bits by a sequential coding process utilizing four internal states, selecting one out of 2r+1 discrete carrier signal values as a function of each r+1 expanded bit group, the selection being made so that 2r-1 carrier signal values correspond to each transition from one internal state of the coding process to one of two possible follower states and that the 2r-1 carrier signal values have a larger minimum distance from each other than the absolute minimum distance within the complete set of discrete carrier signal values, and transmitting the selected discrete carrier signal values in sequence. - View Dependent Claims (2)
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3. A modulation system for causing a carrier signal to assume one of a plurality of finite states as a function of the sequential application of a plurality of information bit signals comprising:
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a sequential coder means including a plurality of terminals (r) for receiving in sequence r bit groups of signals each said r bit group having bits x0n, x1n . . . x(r-1)n, means responsive to the bits for providing coded bits according to the relations;
space="preserve" listing-type="equation">1) y02.sub. n = x0.sub.n ⊕
x0.sub.n-2, and
space="preserve" listing-type="equation">2) y01.sub. n = x0.sub.n ⊕
x0.sub.n-1 ⊕
x0.sub.n-2, and
space="preserve" listing-type="equation">3) y1.sub.n = x1.sub.n, thru
space="preserve" listing-type="equation">4) y(r-1).sub.n = x(r-1).sub.n ;modulating means for modulating a carrier signal to assume in sequence one of 2r+1 discrete signal values in response to the output of the sequential coder means, the discrete signal values being separated from each other such that the complete set of signal values can be subdivided into two pairs of subsets (A, B and C, D), in which
space="preserve" listing-type="equation">d.sub.min I >
d.sub.min G >
d.sub.min Mwhere, dmin I = minimum distance between signal values within a given subset, dmin G = minimum distance between signal values within a pair of subsets, and dmin M = minimum distance between signal values within the complete set, the connections between the sequential coder outputs and the modulator inputs being arranged so that the outputs y01n and y02n selects the subset of signal values and the remaining outputs associated with the bit group select the assigned signal value within the selected subset. - View Dependent Claims (4)
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Specification