A code acquisition module for a direct sequence spread spectrum (DSSS) receiver includes: a Sparse Discrete Fourier transform (SDFT) module configured to perform an SDFT on a finite number of non-uniformly distributed frequencies comprising a preamble of a received DSSS frame to calculate Fourier coefficients for the finite number of non-uniformly distributed frequencies; a multiplier configured to multiply the Fourier coefficients for the finite number of non-uniformly distributed frequencies of the received DSSS frame by complex conjugate Fourier coefficients for the finite number of non-uniformly distributed frequencies to generate a cross-correlation of the received DSSS frame and the complex conjugate Fourier coefficients; and a filter module configured to input the cross-correlation and output a delay estimation for the received DSSS frame.

A code acquisition module for a direct sequence spread spectrum (DSSS) receiver includes: a Sparse Discrete Fourier transform (SDFT) module configured to perform an SDFT on a finite number of non-uniformly distributed frequencies comprising a preamble of a received DSSS frame to calculate Fourier coefficients for the finite number of non-uniformly distributed frequencies; a multiplier configured to multiply the Fourier coefficients for the finite number of non-uniformly distributed frequencies of the received DSSS frame by complex conjugate Fourier coefficients for the finite number of non-uniformly distributed frequencies to generate a cross-correlation of the received DSSS frame and the complex conjugate Fourier coefficients; and a filter module configured to input the cross-correlation and output a delay estimation for the received DSSS frame.

A radio frequency transmission system and methods for mitigating multipath radio frequency interference are disclosed. Embodiments include a first helical antenna having a first radius and operable to receive a first electromagnetic signal, and a second helical antenna having a second radius and operable to receive a second electromagnetic signal. Further embodiments include a phase adjuster configured to receive the first electromagnetic signal as an input signal, apply an adjustable phase delay to the input signal, and output an adjusted electromagnetic signal. Still further embodiments include a signal combiner configured to receive the adjusted electromagnetic signal and the second electromagnetic signal and output a combined electromagnetic signal.

A radio frequency transmission system and methods for mitigating multipath radio frequency interference are disclosed. Embodiments include a first helical antenna having a first radius and operable to receive a first electromagnetic signal, and a second helical antenna having a second radius and operable to receive a second electromagnetic signal. Further embodiments include a phase adjuster configured to receive the first electromagnetic signal as an input signal, apply an adjustable phase delay to the input signal, and output an adjusted electromagnetic signal. Still further embodiments include a signal combiner configured to receive the adjusted electromagnetic signal and the second electromagnetic signal and output a combined electromagnetic signal.

A testing system includes: a bilinear polarized antenna for receiving and dividing a circularly polarized radio wave associating with a horizontal and a vertical polarization path of an object-to-be-tested into a first and a second high frequency signal; a phase retarder for delaying a phase of the first high frequency signal by 90 degrees to form a first high frequency signal with a phase delay of 90 degrees; a power splitter for receiving or synthesizing the first high frequency signal with the phase delay of 90 degrees and the second high frequency signal; and a high frequency signal transceiver for measuring power of the first high frequency signal with the phase delay of 90 degrees and the second high frequency signal and determining states of the horizontal and vertical polarization paths of the object-to-be-tested based on the power. Therefore, the testing system can speed up testing of the object-to-be-tested.

A testing system includes: a bilinear polarized antenna for receiving and dividing a circularly polarized radio wave associating with a horizontal and a vertical polarization path of an object-to-be-tested into a first and a second high frequency signal; a phase retarder for delaying a phase of the first high frequency signal by 90 degrees to form a first high frequency signal with a phase delay of 90 degrees; a power splitter for receiving or synthesizing the first high frequency signal with the phase delay of 90 degrees and the second high frequency signal; and a high frequency signal transceiver for measuring power of the first high frequency signal with the phase delay of 90 degrees and the second high frequency signal and determining states of the horizontal and vertical polarization paths of the object-to-be-tested based on the power. Therefore, the testing system can speed up testing of the object-to-be-tested.

A testing system includes: a bilinear polarized antenna for receiving and dividing a circularly polarized radio wave associating with a horizontal and a vertical polarization path of an object-to-be-tested into a first and a second high frequency signal; a phase retarder for delaying a phase of the first high frequency signal by 90 degrees to form a first high frequency signal with a phase delay of 90 degrees; a power splitter for receiving or synthesizing the first high frequency signal with the phase delay of 90 degrees and the second high frequency signal; and a high frequency signal transceiver for measuring power of the first high frequency signal with the phase delay of 90 degrees and the second high frequency signal and determining states of the horizontal and vertical polarization paths of the object-to-be-tested based on the power. Therefore, the testing system can speed up testing of the object-to-be-tested.

A testing system includes: a bilinear polarized antenna for receiving and dividing a circularly polarized radio wave associating with a horizontal and a vertical polarization path of an object-to-be-tested into a first and a second high frequency signal; a phase retarder for delaying a phase of the first high frequency signal by 90 degrees to form a first high frequency signal with a phase delay of 90 degrees; a power splitter for receiving or synthesizing the first high frequency signal with the phase delay of 90 degrees and the second high frequency signal; and a high frequency signal transceiver for measuring power of the first high frequency signal with the phase delay of 90 degrees and the second high frequency signal and determining states of the horizontal and vertical polarization paths of the object-to-be-tested based on the power. Therefore, the testing system can speed up testing of the object-to-be-tested.

The invention pertains to methods and apparatus for non-systematic complex coded unique word DFT spread orthogonal frequency division multiplexing.

The invention pertains to methods and apparatus for non-systematic complex coded unique word DFT spread orthogonal frequency division multiplexing.