초록 ▼

A method and apparatus for baseband synchronizing of a local PN code sequence with a received PN code sequence incorporated in a received spread spectrum signal is provided. The received spread spectrum signal is translated to baseband to produce an I (in-phase) channel baseband signal and a Q (quad

A method and apparatus for baseband synchronizing of a local PN code sequence with a received PN code sequence incorporated in a received spread spectrum signal is provided. The received spread spectrum signal is translated to baseband to produce an I (in-phase) channel baseband signal and a Q (quadrature-phase) channel baseband signal. Data and error baseband correlators correlate the I channel and Q channel baseband signals with in-phase and quadrature-phase PN signals incorporating the local PN code sequence to produce despread on-time, advanced and delayed I channel and Q channel baseband signals. These despread baseband signals are processed and combined to produce an error signal proportional to a difference between the local PN code sequence and the received PN code sequence. A numerically-controlled oscillator circuit is responsive to the error signal to advance or delay the phase of a reference PN clock signal used to form a local PN clock signal. In operation, the rate of reading the local PN code sequence is accelerated or retarded to synchronize the local and the received PN code sequences.

대표청구항 ▼

A baseband tracking loop for synchronizing a local PN code sequence with a received PN code sequence incorporated in a received spread spectrum signal, comprising: means for reading said local PN code sequence; means for translating said received spread spectrum signal to baseband to produce an I (i

A baseband tracking loop for synchronizing a local PN code sequence with a received PN code sequence incorporated in a received spread spectrum signal, comprising: means for reading said local PN code sequence; means for translating said received spread spectrum signal to baseband to produce an I (in-phase) channel baseband signal and a Q (quadrature-phase) channel baseband signal; first means for correlating said I channel and Q channel baseband signals with in-phase and quadrature-phase PN signals incorporating said local PN code sequence to produce despread on-time I channel and Q channel baseband signals; means for advancing or delaying said in-phase and quadrature-phase PN signals incorporated in said local PN code sequence; second means for correlating said I channel and Q channel baseband signals with the advanced and delayed versions of said in-phase and quadrature-phase PN signals incorporating said local PN code sequence to produce despread advanced and delayed I channel and Q channel baseband signals; means for combining the outputs of said first and second means for correlating to produce an error signal proportional to a difference between said local PN code sequence and said received PN code sequence; and means responsive to said error signal for forming a local PN clock signal from a reference PN clock signal, said local PN clock signal being used to control the reading of said local PN code sequence, wherein the rate of reading said local PN code sequence is accelerated or retarded to synchronize said local and received PN code sequences.