Spread spectrum optical time domain reflectometer

Claim 2

Apparatus for testing return signals in an electrical or optical communications medium, the apparatus comprising: a timing control circuit producing a sequence {.sup.φ k} k of pulse clock signals at successive clock cycles; a word generator for receiving the sequence of pulse clock signals and for generating and issuing a set of four code sequences {r m k } k (m=1,2,3,4), two of which may be identical, for each pulse clock signal k, where the code sequence values r m k are all non-negative or all non-positive and are determined by the relationships r.sup.1.sub.k =b.sup.L.sub.k +G.sup.1.sub.k, r.sup.2.sub.k =b.sup.L.sub.k +G.sup.2.sub.k, r.sup.3.sub.k =r.sup.4.sub.k =b.sup.L.sub.k, where the two sequences {G m k } k (m=1,2) form a Golay pair of complementary code sequences of length L that satisfy the relation ##EQU16## where L is an integer greater than one, where δ ik is the Kronecker delta symbol, and where {b L k }hd k is a sequence having L consecutive terms equal to one or to a fixed non-zero constant value, with all other terms of the sequence being zero, the word generator further generating and issuing two correlation sequences {c m k } k (m=1,2,3,4) defined by c.sup.1.sub.k =c.sup.3.sub.k =G.sup.1.sub.k, c.sup.2.sub.k =c.sup.4.sub.k =G.sup.2.sub.k ; injection means for receiving the pulse clock signal sequence {φ k } k , for receiving a signal sequence {r m k } k from the word generator, and for injecting this sequence in successive clock cycles k into the communications medium; detection means for receiving the pulse clock signal {φ k } k and for detecting a return signal sequence {x m k } k produced by the communications medium in successive clock cycles k in response to injection of the signal sequence {r m k } k for each integer m=1,2,3,4; and processing means for receiving the pulse clock signal sequence {φ k } k , for receiving the return signal sequence {x m k } k in successive clock cycles k, and for forming a linear combination z k of the four return signal sequences ##EQU17## where the sequence {z k } k represents the return signal for a pulse input signal injected into the communication medium.

Claim 3

Apparatus for testing return signals in an electrical or optical communications medium, the apparatus comprising: a timing control circuit producing a sequence {φ k } k of pulse clock signals at successive clock cycles; a word generator for receiving the sequence of pulse clock signals and for generating and issuing a set of 2M code sequences {r m k } k (m=1,2, . . . , 2M) for each pulse clock signal k, where the code sequence values r m k are all non-negative or all non-positive and are determined by the relationships r.sup.m.sub.k =b.sup.L.sub.k +G.sup.m.sub.k (m=1,2,3,4), where the two sequences {G m k } k (m=1,2) from a first Golay pair of complementary code sequences of length L that satisfy the relation ##EQU18## where the two sequences {G m k } k (m=3,4) form a second Golay pair of complementary code sequences of length L that satisfy the relation ##EQU19## where the four Golay code sequences {G m k } k (m=1,2,3,4) satisfy the relation ##EQU20## where L is an integer greater than one, δ ik is the Kronecker delta symbol, and {b L k } k is a sequence having L consecutive terms equal to one or to a fixed non-zero constant value, with all other terms of this sequence being zero, the word generator further generating and issuing for correlation sequences {c m k { k (m,2,3,4) defined by c.sup.1.sub.k =G.sup.1.sub.k -G.sup.2.sub.k =-c.sup.2.sub.k, c.sup.3.sub.k =G.sup.3.sub.k -G.sup.4.sub.k =-c.sup.4.sub.k ; injection means for receiving the pulse clock signal sequence {φ k } k , for receiving a signal sequence {r m k } k from the word generator, and for injecting this sequence in successive clock cycles k into the communications medium; detection means for receiving the pulse clock signal {φ k } k and for detecting a return signal sequence {x m k } k produced by the communications medium in successive clock cycles k in response to injection of the signal sequence {r m k } k for each integer m=1,2,3,4; and processing means for receiving the pulse clock signal sequence {φ k } k , for receiving the return signal sequence {x m k } k in successive clock cycles k, and for forming a linear combination z k of the four return signal sequences ##EQU21## where the sequence {z k } k represents the return signal for a pulse input signal injected into the communications medium.

Claim 4

Apparatus for testing return signals in an electrical or optical communications medium, the apparatus comprising: a timing control circuit producing a sequence {φ k } k of pulse clock signals at successive clock cycles; a word generator for receiving the sequence of pulse clock signals and for generating and issuing a set of 2M code sequences {r m k } k (m=1,2, . . . , 2M) for each pulse clock signal k, where the code sequence values r m k are all non-negative or all non-positive and are determined by the relationships r.sup.m.sub.k =b.sup.L.sub.k +G.sup.m.sub.k (m=1,2,3,4), where the two sequences {G m k } k (m=1,2) from a first Golay pair of complementary code sequences of length L that satisfy the relation ##EQU18## where the two sequences {G m k } k (m=3,4) form a second Golay pair of complementary code sequences of length L that satisfy the relation ##EQU19## where the four Golay code sequences {G m k } k (m=1,2,3,4) satisfy the relation ##EQU20## where L is an integer greater than one, δ ik is the Kronecker delta symbol, and {b L k } k is a sequence having L consecutive terms equal to one or to a fixed non-zero constant value, with all other terms of this sequence being zero, the word generator further generating and issuing for correlation sequences {c m k { k (m,2,3,4) defined by c.sup.1.sub.k =G.sup.1.sub.k -G.sup.2.sub.k =-c.sup.2.sub.k, c.sup.3.sub.k =G.sup.3.sub.k -G.sup.4.sub.k =-c.sup.4.sub.k ; injection means for receiving the pulse clock signal sequence {φ k } k , for receiving a signal sequence {r m k } k from the word generator, and for injecting this sequence in successive clock cycles k into the communications medium; detection means for receiving the pulse clock signal {φ k } k and for detecting a return signal sequence {x m k } k produced by the communications medium in successive clock cycles k in response to injection of the signal sequence {r m k } k for each integer m=1,2,3,4; and processing means for receiving the pulse clock signal sequence {φ k } k , for receiving the return signal sequence {x m k } k in successive clock cycles k, and for forming a linear combination z k of the four return signal sequences ##EQU21## where the sequence {z k } k represents the return signal for a pulse input signal injected into the communications medium.

Claim 5

Apparatus for testing return signals in an electrical or optical communications medium, the apparatus comprising: a timing control circuit producing a sequence {φ k } k of pulse clock signals; a word generator for receiving the sequence of pulse clock signals and for generating and issuing a set of four code sequences { n r m k } k (m=1,2,3,4) for each pulse clock signal k for a fixed integer n≧0, where the code sequence values n r m k are all non-negative or all non-positive and are determined by the relationships .sup.n r.sup.1.sub.k =b.sup.L.sub.k +.sup.n G.sup.1.sub.k, .sup.n r.sup.2.sub.k =b.sup.L.sub.k -.sup.n G.sup.1.sub.k, .sup.n r.sup.3.sub.k =b.sup.L.sub.k +.sup.n G.sup.2.sub.k, .sup.n r.sup.4.sub.k =b.sup.L.sub.k -.sup.n G.sup.2.sub.k, where L=2 n for a positive integer n, where {b L k } k is a sequence having L consecutive terms equal to one or to a fixed non-zero constant value, with all other values of the sequence being zero, where { n G 1 k } k and { n G 2 k } k form a Golay pair of complementary code sequences of length L that satisfy the relation ##EQU22## where δ ik is the Kronecker delta, and where the Golay pair of code sequences { n+1 G 1 k } k and { n+1 G 2 k } k for an integer n+1≧1, are generated inductively by the relationships .sup. G.sup.1.sub.k ={1}, .sup.0 G.sup.2.sub.k ={1}, .sup.n+1 G.sup.1.sub.k ={.sup.n G.sup.1.sub.k, .sup.n G.sup.2.sub.k }, (n≧0) .sup.n+1 G.sup.1.sub.k ={.sup.n G.sup.1.sub.k, -.sup.n G.sup.2.sub.k }, (n≧0) the word generator further generating and issuing a correlation sequence { n c m k } k of length L=2 n corresponding to each sequence { n r m k } k (m=1,2,3,4) and being defined by .sup.n c.sup.1.sub.k =.sup.n G.sup.1.sub.k =-.sup.n c.sup.2.sub.k, .sup.n c.sup.3.sub.k =.sup.n G.sup.2.sub.k =--.sup.n c.sup.4.sub.k ; injection means for receiving the pulse clock signal sequence {φ k } k , for receiving a signal sequence { n r m k } k from the word generator, and for injecting this sequence in successive clock cycles k into the communications medium; detection means for receiving the pulse clock signal {φ k } k and for detecting a return signal sequence { n x m k } k produced by the communications medium in successive clock cycles k in response to injection of the signal sequence { n r m k } k for each integer m=1,2,3,4; and processing means for receiving the pulse clock signal sequence {φ k } k , for receiving the return signal sequence { n x m k } k in successive clock cycles k, and for forming a linear combination n z k of the four return signal sequences defined by ##EQU23## where the sequence { n z k } k represents the return signal for a pulse input signal injected into the communications medium.

Claim 6

Apparatus for testing return signals in an electrical or optical communications medium, the apparatus comprising: a timing control circuit producing a sequence {φ k } k of pulse clock signals; a word generator for receiving the sequence of pulse clock signals and for generating and issuing a set of four code sequences { n r m k } k (m=1,2,3,4) for each pulse clock signal k for a fixed integer n≧0, where the code sequence values n r m k are all non-negative or all non-positive and are determined by the relationships .sup.n r.sup.1.sub.k =b.sup.L.sub.k +.sup.n G.sup.1.sub.k, .sup.n r.sup.2.sub.k =b.sup.L.sub.k -.sup.n G.sup.1.sub.k, .sup.n r.sup.3.sub.k =b.sup.L.sub.k +.sup.n G.sup.2.sub.k, .sup.n r.sup.4.sub.k =b.sup.L.sub.k -.sup.n G.sup.2.sub.k, where L=2 n for a positive integer n, where {b L k } k is a sequence having L consecutive terms equal to one or to a fixed non-zero constant value, with all other values of the sequence being zero, where { n G 1 k } k and { n G 2 k } k form a Golay pair of complementary code sequences of length L that satisfy the relation ##EQU22## where δ ik is the Kronecker delta, and where the Golay pair of code sequences { n+1 G 1 k } k and { n+1 G 2 k } k for an integer n+1≧1, are generated inductively by the relationships .sup. G.sup.1.sub.k ={1}, .sup.0 G.sup.2.sub.k ={1}, .sup.n+1 G.sup.1.sub.k ={.sup.n G.sup.1.sub.k, .sup.n G.sup.2.sub.k }, (n≧0) .sup.n+1 G.sup.1.sub.k ={.sup.n G.sup.1.sub.k, -.sup.n G.sup.2.sub.k }, (n≧0) the word generator further generating and issuing a correlation sequence { n c m k } k of length L=2 n corresponding to each sequence { n r m k } k (m=1,2,3,4) and being defined by .sup.n c.sup.1.sub.k =.sup.n G.sup.1.sub.k =-.sup.n c.sup.2.sub.k, .sup.n c.sup.3.sub.k =.sup.n G.sup.2.sub.k =--.sup.n c.sup.4.sub.k ; injection means for receiving the pulse clock signal sequence {φ k } k , for receiving a signal sequence { n r m k } k from the word generator, and for injecting this sequence in successive clock cycles k into the communications medium; detection means for receiving the pulse clock signal {φ k } k and for detecting a return signal sequence { n x m k } k produced by the communications medium in successive clock cycles k in response to injection of the signal sequence { n r m k } k for each integer m=1,2,3,4; and processing means for receiving the pulse clock signal sequence {φ k } k , for receiving the return signal sequence { n x m k } k in successive clock cycles k, and for forming a linear combination n z k of the four return signal sequences defined by ##EQU23## where the sequence { n z k } k represents the return signal for a pulse input signal injected into the communications medium.

Claim 7

Apparatus for testing return signals in an electrical or optical communications medium, the apparatus comprising: a timing control circuit producing a sequence {φ k } k of pulse clock signals; a word generator for receiving the sequence of pulse clock signals and for generating and issuing a set of four code sequences { n r m k } k (m=1,2,3,4) for each pulse clock signal k for a fixed integer n≧0, where the code sequence values n r m k are all non-negative or all non-positive and are determined by the relationships .sup.n r.sup.1.sub.k =b.sup.L.sub.k +.sup.n G.sup.1.sub.k, .sup.n r.sup.2.sub.k =b.sup.L.sub.k -.sup.n G.sup.1.sub.k, .sup.n r.sup.3.sub.k =b.sup.L.sub.k +.sup.n G.sup.2.sub.k, .sup.n r.sup.4.sub.k =b.sup.L.sub.k -.sup.n G.sup.2.sub.k, where L=2 n for a positive integer n, where {b L k } k is a sequence having L consecutive terms equal to one or to a fixed non-zero constant value with all other values of the sequence being zero, where { n G 1 k } k and { n G 2 k } k form a Golay pair of complementary code sequences of length L that satisfy the relation ##EQU24## where δ ik s the Kronecker delta, and where the Golay pair of code sequences { n+1 G 1 k } k and { n+1 G 2 k } k for an integer n+1≧1, are generated inductively by the relationships .sup. G.sup.1.sub.k ={1}, .sup.0 G.sup.2.sub.k ={1}, .sup.n+1 G.sup.1.sub.k ={.sup.n G.sup.1.sub.k, .sup.n G.sup.2.sub.k }, (n≧0) .sup.n+1 G.sup.1.sub.k ={-.sup.n G.sup.1.sub.k, .sup.n G.sup.2.sub.k }, (n≧0) the word generator further generating and issuing a correlation sequence { n c m k } k of length L=2 n corresponding to each sequence { n r m k } k (m=1,2,3,4) and being defined by .sup.n c.sup.1.sub.k =.sup.n G.sup.1.sub.k =-.sup.n c.sup.2.sub.k, .sup.n c.sup.3.sub.k =.sup.n G.sup.2.sub.k =-.sup.n c.sup.4.sub.k ; injection means for receiving the pulse clock signal sequence {φ k } k , for receiving a signal sequence { n r m k } k from the word generator, and for injecting this sequence in successive clock cycles k into the communications medium; detection means for receiving the pulse clock signal {φ k } k and for detecting s return signal sequence { n x m k } k produced by the communications medium in successive clock cycles k in response to injection of the signal sequence { n r m k } k for each integer m+1,2,3,4; and processing means for receiving the pulse clock signal sequence {φ k } k , for receiving the return signal sequence { n x m k } k in successive clock cycles k, and for forming a linear combination n z k of the four return signal sequences defined by ##EQU25## where the sequence { n z k } k represents the return signal for a pulse input signal injected into the communications medium.

Claim 8

Apparatus for testing return signals in an electrical or optical communications medium, the apparatus comprising: a timing control circuit producing a sequence {φ k } k of pulse clock signals; a word generator for receiving the sequence of pulse clock signals and for generating and issuing a set of four code sequences { n r m k } k (m=1,2,3,4) for each pulse clock signal k for a fixed integer n≧0, where the code sequence values n r m k are all non-negative or all non-positive and are determined by the relationships .sup.n r.sup.1.sub.k =b.sup.L.sub.k +.sup.n G.sup.1.sub.k, .sup.n r.sup.2.sub.k =b.sup.L.sub.k -.sup.n G.sup.1.sub.k, .sup.n r.sup.3.sub.k =b.sup.L.sub.k +.sup.n G.sup.2.sub.k, .sup.n r.sup.4.sub.k =b.sup.L.sub.k -.sup.n G.sup.2.sub.k, where L=2 n for a positive integer n, where {b L k } k is a sequence having L consecutive terms equal to one or to a fixed non-zero constant value with all other values of the sequence being zero, where { n G 1 k } k and { n G 2 k } k form a Golay pair of complementary code sequences of length L that satisfy the relation ##EQU24## where δ ik s the Kronecker delta, and where the Golay pair of code sequences { n+1 G 1 k } k and { n+1 G 2 k } k for an integer n+1≧1, are generated inductively by the relationships .sup. G.sup.1.sub.k ={1}, .sup.0 G.sup.2.sub.k ={1}, .sup.n+1 G.sup.1.sub.k ={.sup.n G.sup.1.sub.k, .sup.n G.sup.2.sub.k }, (n≧0) .sup.n+1 G.sup.1.sub.k ={-.sup.n G.sup.1.sub.k, .sup.n G.sup.2.sub.k }, (n≧0) the word generator further generating and issuing a correlation sequence { n c m k } k of length L=2 n corresponding to each sequence { n r m k } k (m=1,2,3,4) and being defined by .sup.n c.sup.1.sub.k =.sup.n G.sup.1.sub.k =-.sup.n c.sup.2.sub.k, .sup.n c.sup.3.sub.k =.sup.n G.sup.2.sub.k =-.sup.n c.sup.4.sub.k ; injection means for receiving the pulse clock signal sequence {φ k } k , for receiving a signal sequence { n r m k } k from the word generator, and for injecting this sequence in successive clock cycles k into the communications medium; detection means for receiving the pulse clock signal {φ k } k and for detecting s return signal sequence { n x m k } k produced by the communications medium in successive clock cycles k in response to injection of the signal sequence { n r m k } k for each integer m+1,2,3,4; and processing means for receiving the pulse clock signal sequence {φ k } k , for receiving the return signal sequence { n x m k } k in successive clock cycles k, and for forming a linear combination n z k of the four return signal sequences defined by ##EQU25## where the sequence { n z k } k represents the return signal for a pulse input signal injected into the communications medium.