Multilevel mate pair code compressor for codes expanded by the process of butting
AssigneeThe United States of America as represented by the Secretary of the Army
InventorFrank S. Gutleber
Life of this patent
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Abstract
Multilevel code mates A and B expanded in accordance with the expression , b.sup.K and B=a.sup.K, b are compressed to a lobeless basic mate pair by repeatedly compressing corresponding code mate pairs in successive stages to provide diminishing codes of half the code length by amplifying the code mates by a predetermined amplification factor and then adding and subtracting the code mates in accordance with the expressions A.sub.i-1 =A.sub.i +B.sub.i.sup.K.sbsp.i and B.sub.i-1 =A.sub.i.sup.K.sbsp.i -B.sub.i where i is the i.sub.th compression stage and K.sub.i is the amplification factor applied to the codes A.sub.i and B.sub.i.
Claims21
A method of compressing a pair of multilevel expanded digital noise codes comprised of first and second multilevel code mates in successive multiple stages where the expanded noise codes are comprised of a predetermined number of code bits defining the code length of said code mates, comprising the steps of:
- at each stage,
- applying first and second multilevel expanded code mates;
- generating third and fourth multilevel code mates by respectively multiplying said first and second code mates by a predetermined gain factor, said predetermined gain factor being non-unity for at least one said each stage of said multiple stages;
- combining said first multilevel code mate with said fourth multilevel code mate in a first mathematical sense to form a first compressed code mate having a code length one half that of the preceding stage;
- combining said third multilevel code mate with said second multilevel code mate in a second mathematical sense to form a second compressed code mate also having a code length one half that of the preceding stage;
- and
- delaying said first compressed code mate by a time delay equal to said one half expanded code length prior to applying said first and second compressed code mates to the next stage whereby said compressed code mates become the expanded code mate for the said next stage.
Apparatus for compressing a pair of expanded noise codes comprised of first and second multilevel code mates and having a predetermined number of code bits defining the code length of said code mates, comprising:
- a plurality of series coupled compression stages, each stage including,
- means for generating third and fourth multilevel code mates respectively comprised of first and second multi-level input code mates multiplied by a predetermined gain factor, said predetermined gain factor being non-unity for at least one said each stage of said plurality of compression stages;
- means for combining said first multilevel code mate with said fourth multilevel code mate in a first manner to form a first compressed code mate having a code length one half that of the first and second multilevel input code mates;
- means for combining said third multilevel code mate with said second multilevel code mate in a second manner to form a second compressed code mate also having a code length one half that of the first and second input code mates;
- and
- means for delaying said first compressed code mate by a time delay equal to said one half expanded code length for providing a first output code mate coincident in time with said second compressed code mate, said second compressed code mate being a second output code mate.
Dependencies are inferred from the claim text.