US 4,809,295 A · Code lengthening system

Abstract

Apparatus and a method of generating very very long pseudonoise (PN) spread spectrum codes is provided where the code is so long that it need never repeat itself during actual use. The transmitter is adapted to start to transmit one set of a plurality of component codes as a composite code having correlation properties with the component codes. When the first set of component codes are acquired at the receiver the composite code is then transmitted as a component of a different composite code which contains the previous composite code and a second new set of component codes which have correlation properties with the new set of component codes. When the second set of component codes are acquired by the receiver the composite code is then transmitted as a third new and different composite code which contains a third new set of component codes which have correlation properties with third new set of component codes. When the third new set of component set of codes is required the transmitter is already transmitting a very very long composite code but may lengthen the composite code by employing further set of component codes or may continue to transmit the very very long composite code without having any correlation properties with any of the component codes being transmitted.

Claims8

Dependent claims

A method of transmitting and rapidly acquiring substantially non-repeating pseudonoise (PN) spread spectrum codes, comprising the steps of:

transmitting a first composite code comprising a first plurality of individual component codes X.sub.1, Y.sub.1, Z.sub.1 having correlation properties with the component codes,
sequentially acquiring each of the component codes X.sub.1, Y.sub.1, Z.sub.1 until the composite code having correlation properties with the first plurality of component codes is acquired,
transmitting a second composite code comprising a second plurality of individual component codes Y.sub.2, Z.sub.2 and the composite of said first plurality of individual component codes treated as a component code where said second composite code has correlation properties with said individual component codes Y.sub.2 and Z.sub.2,
sequentially acquiring each of said component codes Y.sub.2 and Z.sub.2 until the composite code being transmitted is acquired,
transmitting n.sup.th composite code comprising a n.sup.th plurality individual component codes Y.sub.n, Z.sub.n and the composite of said first and said second plurality of individual component codes treated as a component code where said n.sup.th composite code has correlation properties with said individual component codes Y.sub.n and Z.sub.n, and
sequentially acquiring each of said component codes Y.sub.n and Z.sub.n until the modulo two (MOD) composite code MOD (X.sub.1, Y.sub.1, Z.sub.1, Y.sub.2, Z.sub.2, Y.sub.n, Z.sub.n) which comprises the substantially non-repeating composite code is acquired.

3 more elements

A system for generating substantially non-repeating pseudonoise (PN) codes capable of rapid of acquisition, comprising:

a transmitter,
a multiplexer in the transmitter,
a first majority vote (MAJ) composite code generator connected to a first plurality of component code generators X.sub.1, Y.sub.1 and Z.sub.1 for producing at the input of said multiplexer a composite code MAJ (X.sub.1, Y.sub.1, Z.sub.1),
a first modulo two (MOD) composite code generator connected to said first plurality of component code generators (X.sub.1, Y.sub.1 and Z.sub.1) for producing at its output a composite code MOD (X.sub.1, Y.sub.1 and Z.sub.1),
a second majority vote (MAJ) composite code generator connected to a second plurality of component code generators Y.sub.2 and Z.sub.2 and to the output of the said first modulo two composite code generator for producing at the input of said multiplexer a composite code MAJ [MOD(X.sub.1, Y.sub.1, Z.sub.1), Y.sub.2, Z.sub.2 ],
a second modulo two (MOD) composite code generator connected to said second plurality of component code generators Y.sub.2 and Z.sub.2 and to the output of said first modulo two (MOD) composite code generator for producing at its output the composite code MOD (X.sub.1, Y.sub.1, Z.sub.1, Y.sub.2, Z.sub.2),
an n.sup.th majority vote (MAJ) composite code generator connected to an n.sup.th plurality of component code generators Y.sub.n and Z.sub.n and to the output of said n-1.sup.th modulo two (MOD) composite code generator for producing at the input of said multiplexer a composite code MAJ [MOD(X.sub.1, Y.sub.1, Z.sub.1, Y.sub.2, Z.sub.2,--), Y.sub.n, Z.sub.n ],
an n.sup.th modulo two (MOD) composite code generator connected to said n.sup.th plurality of component code generators Y.sub.n, Z.sub.n and to the output of the n-1.sup.th modulo two (MOD) composite code generator for producing at its output and at the input of said multiplexer a composite code MOD (X.sub.1, Y.sub.1, Z.sub.1, Y.sub.2, Z.sub.2, --Y.sub.n, Z.sub.n) which includes the MOD of all component code generators,
a transmitter antenna coupled to the output of said multiplexer, and
selector means coupled to said multiplexer for initially selecting the output of said first majority vote composite code generator for transmission enabling acquisition of the component codes X.sub.1, Y.sub.1, and Z.sub.1 and for sequentially switching to said second and then said third majority vote composite code generators and then to said n.sup.th modulo two composite code generator to enable acquisition of the remaining component codes Y.sub.2, Z.sub.2 and Y.sub.n and Z.sub.n before transmitting the MOD of all component code generators MOD (X.sub.1, Y.sub.1, Z.sub.1, Y.sub.2, Z.sub.2 --Y.sub.n, Z.sub.n).

7 more elements

Dependencies are inferred from the claim text.

Code lengthening system

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Code lengthening system

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Abstract

Claims8