Method and apparatus for despreading spread spectrum signals

A PN generator comprising:

• a shift register coupled to a received spread spectrum signal, said shift register comprising a plurality of stages,
• a plurality of taps connected to said shift register, each of said taps providing a delayed version of said received spread spectrum signal,
• a modulo-two adder coupled to each of said taps and to said received spread spectrum signal,
• a sequence detector coupled to said modulo-two adder, whereby a sequence indicative of a spread spectrum code in said spread spectrum signal may be identified, and
• said taps are positioned along said shift register such that said modulo-two adder outputs the same chip value repeatedly for a minimum duration when said spread spectrum code is received.

A PN generator comprising:

• a shift register coupled to a received spread spectrum signal, said shift register comprising a plurality of stages,
• a plurality of taps connected to said shift register, each of said taps providing a delayed version of said received spread spectrum signal,
• a modulo-two adder coupled to each of said taps and to said received spread spectrum signal,
• a sequence detector coupled to said modulo-two adder, whereby a sequence indicative of a spread spectrum code in said spread spectrum signal may be identified, and
• a reset signal whereby said shift register may periodically be reset to a predetermined sequence.

A PN generator comprising:

• a shift register coupled to a received spread spectrum signal, said shift register comprising a plurality of stages,
• a plurality of tap sets connected to said shift register, each of said tap sets defining a different spreading code,
• means connected to each of said tap sets for generating a recognition signal indicating a likelihood of having received one of said spreading codes,
• a symbol detector coupled to each of said recognition signals, and outputting a signal indicative of one of said spreading codes in response thereto
• wherein said spreading codes are symbol codes, and
• wherein each of said recognition signals comprises a sequence of chips, and said symbol detector comprises an accumulator whereby a correlation value corresponding to each of said recognition signals is generated.