An apparatus for detecting global navigation satellite system (GNSS) spoofing, including a GNSS receiver that includes a first radio-frequency front-end (RF1) connected to antenna 1; a second radio-frequency front-end (RF2) connected to antenna 2; a digital section connected to both RF1 and RF2 and controlled with a single frequency oscillator. The digital section generates a first set of GNSS raw measurements based on signals received from antenna 1; generates a second set of GNSS raw measurements based on signals received from antenna 2; computes single differences between simultaneous raw measurements, generated with the signals received from the antenna 1 and the antenna 2 for the same GNSS satellite; compares the single differences with a threshold; and issues a spoofing alert when more than one of the single differences is below a threshold.