Code generator for multilevel interleaved multiplexed noise codes
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
Expanded multilevel noise codes are generated of a type termed "code mates" aving autocorrelation functions which, upon detection in a matched filter, provide an impulse autocorrelation function. More particularly, expanded multilevel code mate pairs are generated by interleaving two multi-bit codes comprising a mate pair wherein one of the codes in each expanded mate pair comprises a code having a larger amplitude than the other code and whose position is mutually transposed in the expanded mate pairs and further wherein one of the interleaved codes is the complement or negative of one of the original or basic code mates.
Claims23
A method expanding a pair of digital codes, comprising the steps of:
- generating first and second time coincident multibit digital codes of a first amplitude and predetermined equal interpulse periods between code bits;
- generating a third code comprising the complement of one of said first and second codes;
- selectively altering the amplitudes of two codes selected from said first, second and third codes to provide first and second codes of a second amplitude;
- generating a first expanded code comprised of first and second interleaved code portions by selectively combining a said first code of first amplitude with a delayed said second code of second amplitude, said delay being less than said interpulse periods of said first and second codes of a first amplitude;
- generating a second expanded code comprised of first and second interleaved code portions by selectively combining a said first code of second amplitude with a delayed said second code of first amplitude, said delay being the same as the delay of said second code of second amplitude, and
- wherein one code portion of said code portions of said first and second expanded codes comprises said third code, said third code further being selectively of a first or second amplitude.
A method of expanding a pair of digital codes into a pair of multilevel digital codes comprising the steps of:
- generating first and second multi-bit digital codes having predetermined interpulse periods;
- delaying said second code by a predetermined time interval which is a function of said interpulse periods of said first and second codes;
- altering the amplitude of said first code and the delayed second code by a predetermined gain factor to provide third and fourth codes, respectively;
- combining said first and fourth codes in a first manner to form a first interleaved multilevel code;
- combining said third code and said delayed second code in a second manner to form a second interleaved multilevel code.
Apparatus for generating a pair of expanded digital codes from a first pair of digital codes, comprising in combination:
- means for generating first and second time multibit coincident digital codes of a first amplitude;
- means for generating a third code comprising the complement of one of said first and second codes;
- means for selectively altering the amplitudes of two codes selected from said first, second and third codes to provide first and second codes of a second amplitude;
- first code interleaving means generating a first expanded code comprised of first and second interleaved code portions including a said first code of first amplitude and a second said code of second amplitude;
- second code interleaving means generating a second expanded code comprised of first and second interleaved code portions including a said first code of second amplitude with a said second code of first amplitude, and
- wherein said one code portion of said interleaved code portions of said first and second expanded codes comprises said third code, said third code further being selectively of a first or second amplitude.
Dependencies are inferred from the claim text.