High processing gain acquisition and demodulation apparatus

An apparatus for rapidly acquiring high processing gain (HPG) Pseudo Noise (PN) coded signals, comprising:

• preamble parallel correlator means for receiving said high processing gain PN coded signals that are set during data symbol time periods, each of which is designated as (T.sub.s), wherein each T.sub.s period comprises a short acquisition preamble header PN code which precedes a long PN code, and said short PN codes have a sequence length that is matched to the length of said preamble parallel correlator,
• PN replica code generation means having its output coupled to the input of said preamble parallel correlator means for sequentially generating values representative of all possible bit alignments of said short PN codes and for sending said values to said preamble parallel correlator,
• alignment detection means coupled to the output of said preamble parallel correlator means for detecting values representative of the alignment of said PN replica codes with said received short PN code,
• bit detection means coupled to the alignment detection means for indicating which of said short PN codes generated by said PN replica code generation means is aligned with said received shod PN code,
• PN generator alignment means coupled to the output of said bit detection means and having an output coupled to said PN replica code generation means for synchronizing the alignment of the short PN replica code with the received PN coded signals, and
• digital demodulation and tracking means coupled to said PN replica code generation means for synchronously receiving said high processing gain PN coded signals and for producing output data signals and for discontinuing the sensing of said short PN codes to said preamble parallel correlator upon synchronization of the alignment of the short PN replica code with the received PN coded signals.