Thomas F Koehler

US Patent:

56466277, Jul 8, 1997

Filed:

Jan 30, 1996

Appl. No.:

8/593962

Inventors:

Carl Myron Willis - Mesa AZ
Thomas Frederick Koehler - Scottsdale AZ

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

G01S 728

US Classification:

342189

Abstract:

This invention relates to a method and apparatus for controlling a biphase modulator (602, 702) to improve autocorrelation in pseudorandom noise coded systems. The biphase modulator modulates a carrier frequency with one of two phase states responsive to a pseudorandom noise (PN) binary code sequence. The spectrum (610, 710) at the output of the biphase modulator comprises a plurality of spectral lines separated by the code repetition frequency, including a center spectral line (611, 711) and at least one adjacent spectral line (612-615, 712-717). The magnitude of the center spectral line is measured and compared to a reference to produce a control signal which is responsive to the magnitude of the center spectral line. This control signal is supplied to the biphase modulator for maintaining a predetermined magnitude of the center spectral line thereby achieving a desired spectrum output and improving autocorrelation of the system.

US Patent:

54971608, Mar 5, 1996

Filed:

Sep 17, 1993

Appl. No.:

8/123508

Inventors:

Thomas F. Koehler - Scottsdale AZ
Carl M. Willis - Mesa AZ

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

G01S 1312
G01S 1328
G01S 1340

US Classification:

342145

Abstract:

A method and apparatus is disclosed for improved out-of-range rejection in pseudo-random noise (PN) coded systems by adjusting the relative phase difference between the two phase states of a bi-phase modulation. The energy in the spectral lines of the bi-phase modulated RF signal to generate a signal to be fedback to a voltage-controlled bi-phase modulator to adjust the relative phase difference between the two phase states. Sampled signals are mixed down to baseband using single sideband suppressed carrier modulation of the center frequency of the transmitted signal and the offset frequency. The offset frequency is chosen to be less than the PN code repetition frequency. The baseband signal is filtered and envelop detected producing a DC voltage proportional to the amplitude of the center line of the PN spectrum which is compared to either a fixed reference or to the amplitude of one or more of the remaining lines in the spectrum. The comparison provides an error signal adjusting the phase of the bi-phase modulator providing improved out-of-range rejection.