TECHNICAL FIELD

The disclosure relates generally to receiver technology, and more specifically to a receiver with a coherent matched filter.

SUMMARY

According to one implementation of the disclosure, a receiver for receiving 1090 MHz Mode S Extended Squitter (“ES”) ADS-B messages includes an analog-to-digital converter configured to convert a received analog signal into a digital representation of the received signal and a carrier detection module configured to determine if a spectral component within a range of 1090 MHz is present within a portion of the digital representation of the received signal. In addition, the receiver includes a cross-correlation module configured to calculate, responsive to a determination by the carrier detection module that a spectral component within the range of 1090 MHz is present within the portion of the digital representation of the received signal, a measure of the cross-correlation between the portion of the digital representation of the received signal and a reference signal representing an expected pulse pattern for a specific portion of a 1090 MHz Mode S ES ADS-B message, the calculated measure of the cross-correlation representing a first measure of the likelihood that the digital representation of the received signal includes a 1090 MHz Mode S ES ADS-B message. The cross-correlation module is further configured to determine if the first measure of the likelihood that the digital representation of the received signal includes a 1090 MHz Mode S ES ADS-B message satisfies a first condition. The receiver also includes a signal estimator module configured to generate, responsive to a determination that the first measure satisfies the first condition, an estimate of a portion of a 1090 MHz Mode S ES ADS-B message potentially included in the digital representation of the received signal corresponding to the portion of the digital representation of the received signal. The receiver further includes a screening module. The screening module is configured to generate a feature vector representing n≥2 features of the estimate of the portion of the 1090 MHz Mode S ES ADS-B potentially included in the digital representation of the received signal, project the feature vector into a corresponding n-dimensional feature space, determine, based on the projection of the feature vector into the feature space, a second measure of the likelihood that the digital representation of the received signal includes a 1090 MHz Mode S ES ADS-B message, and determine if the second measure of the likelihood that the digital representation of the received signal includes a 1090 MHz Mode S ES ADS-B message satisfies a second condition. If it is determined that the second measure satisfies the second condition, the receiver includes a carrier refinement module configured to shift the frequency of carrier pulses in the digital representation of the received signal toward a desired frequency and to align the phase of carrier pulses in the digital representation of the received signal with a desired phase. The receiver also includes a coherent matched filter that is phase-matched to the desired phase and configured to recover a 1090 MHz Mode S ES ADS-B message from the digital representation of the received signal.

Other features of the present disclosure will be apparent in view of the following detailed description of the disclosure and the accompanying drawings. Implementations described herein, including the above-described implementations, may include a method or process, a system, or computer-readable program code embodied on computer-readable media.

