Method and apparatus for removing spoofing signal in satellite navigation system

1. An apparatus for removing a spoofing signal, the apparatus comprising:

a radio frequency (RF)-intermediate frequency (IF) converter to convert a global positioning system (GPS) signal from an RF signal to an IF signal, and to remove a spoofing signal based on whether the spoofing signal is present in the RF signal;

a spoofing signal processor to obtain and track the spoofing signal using the IF signal and to generate a characteristic of the spoofing signal;

an anti-spoofing signal generator to generate an anti-spoofing signal by shifting a phase of the spoofing signal 180 degrees based on the characteristic of the spoofing signal; and

a spoofing signal detector/controller to determine whether the spoofing signal is present and to control the spoofing signal processor and the anti-spoofing signal generator.

2. The apparatus of claim 1 , wherein the RF-IF converter receives the RF signal from a GPS satellite through a GPS antenna, and transmits a spoofing-free RF signal to a GPS receiver producing a GPS solution.

3. The apparatus of claim 1 , wherein the RF-IF converter comprises:

an RF divider to divide the RF signal;

a frequency downconverter to down-convert the divided RF signal into an IF signal;

an analog-digital converter to convert the IF signal from analog to digital;

a digital-analog converter to convert the anti-spoofing signal from a digital IF signal to an analog IF signal;

a frequency upconverter to up-convert the analog IF signal to an RF signal;

an RF mixer to mix the divided RF signal with the up-converted RF signal; and

a clock to enable frequency synchronization between the frequency downconverter and the frequency upconverter.

4. The apparatus of claim 3 , wherein the RF-IF converter transmits the RF signal to the GPS receiver through the RF divider and the RF mixer when the spoofing signal is absent, and generates the anti-spoofing signal using the received UPS signal and removes the spoofing signal using the anti-spoofing signal when the spoofing signal is present.

5. The apparatus of claim 1 , wherein the spoofing signal processor comprises:

a control command receiving unit to receive a control command for processing the spoofing signal from the spoofing signal detector/controller;

a spoofing signal obtaining unit to obtain the spoofing signal using the digital IF signal received from the RF-IF converter;

a spoofing signal tracking unit to track the spoofing signal using the obtained spoofing signal; and

a measurement data generating unit to generate measurement data through signal tracking.

6. The apparatus of claim 1 , wherein the anti-spoofing signal generator comprises:

a measurement data receiving unit to receive the measurement data from the spoofing signal processor;

a signal intensity converting unit to convert a signal intensity based on the received measurement data;

a code position determining unit to determine a code position based on the received measurement data;

a carrier phase determining unit to determine a carrier phase based on the received measurement data; and

an anti-spoofing signal generating unit to generate an anti-spoofing signal based on the determined signal intensity, the determined code position, and the determined carrier phase.

7. The apparatus of claim 1 , wherein the spoofing signal detector/controller comprises:

a GPS data receiving unit to receive measurement data and GPS data from the GPS receiver;

a spoofing signal determining unit to determine whether the spoofing signal is present using the received GPS data;

a spoofing signal detecting unit to detect the spoofing signal based on the determined result; and

a control command generating unit to generate and transmit a control command for removing the detected spoofing signal.

8. A method of removing a spoofing signal, the method comprising:

determining whether a spoofing signal is present in a received GPS signal between a radio frequency (RF) output terminal of a GPS antenna and an RF input terminal of a GPS receiver;

transmitting the received GPS signal to the RF input terminal of the GPS receiver when the spoofing signal is absent;

extracting a characteristic of the spoofing signal when the spoofing signal is present;

generating an anti-spoofing signal based on the extracted characteristic of the spoofing signal; and

removing the spoofing signal using the generated anti-spoofing signal.

9. The method of claim 8 , wherein the determining of whether the spoofing signal is present comprises:

down-converting the received GPS signal from an RF signal to an IF signal; and

converting the IF signal from analog to digital.

10. The method of claim 8 , wherein the extracting of the characteristic of the spoofing signal comprises:

extracting Doppler information, a code position, and a signal intensity using the digital IF signal used to determine whether the spoofing signal is present.

11. The method of claim 8 , wherein the generating of the anti-spoofing signal comprises:

maintaining frequency synchronization with the IF signal processed to extract the characteristic of the spoofing signal.

12. The method of claim 8 , wherein the removing of the spoofing signal comprises:

converting the anti-spoofing signal from a digital IF signal to an analog IF signal;

up-converting the analog IF signal to an RF signal; and

mixing the up-converted anti-spoofing signal with the GPS signal including the spoofing signal.