RADIO TAG FOR LFM RADAR
First Claim
1. A tag apparatus, capable of detecting ,decoding and validating a radar message contained in an AM and FM signal component of a received LFM (linear frequency modulation) pulse waveform from a radar source, and encoding and retransmitting, back to the radar source, a tag message contained in a PM and FM signal component of a modified LFM pulse waveform, the apparatus comprising:
- a) an antenna input circuit for receiving the LFM pulse waveform having digital information;
b) an AM/FM signal component validation circuit, in electrical communication with said antenna, for detecting, decoding and validating said AM and FM components in the LFM waveform, and comparing the components to a predetermined criteria, in electrical communication with said antenna;
c) a delay element in electrical communication with the antenna for storing the received LFM pulse waveform;
d) a chopped repeater circuit, in electrical connection with the delay element for encoding the stored LFM pulse waveform in the delay element with a preprogrammed AM and a FM predetermined criteria to form a modified LFM pulse waveform;
e) timing synchronization circuitry for synchronizing the chopped repeater circuit of the modified LFM pulse waveform with reception of the received LFM pulse; and
f) an antenna output circuit, in electrical communication with the chopped repeater circuit, retransmitting of the modified LFM pulse back to the radar source.
2 Assignments
0 Petitions
Accused Products
Abstract
An RFID system using encoded digital information utilizing pulsed linear frequency modulation (LFM). The LFM waveform is sent from an24 aircraft or satellite and is received by a transponder. The LFM waveform is demodulated using both, an AM and an FM receiver. The demodulated data is compared to preprogrammed criteria tables, and after validation is decoded and utilized. Algorithms in the transponder are used to determine the frequency deviation and for calculating the direction of the slope of the LFM input signal. The valid RF signal is stored in a delay element, encoded with the transponder data using phase modulation (PM), and frequency modulation (FM). The tag transmission is synchronized to the input LFM waveform. The transmit/receive chopping signal prevents unwanted oscillations and is capable of randomization.
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Citations
26 Claims
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1. A tag apparatus, capable of detecting ,decoding and validating a radar message contained in an AM and FM signal component of a received LFM (linear frequency modulation) pulse waveform from a radar source, and encoding and retransmitting, back to the radar source, a tag message contained in a PM and FM signal component of a modified LFM pulse waveform, the apparatus comprising:
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a) an antenna input circuit for receiving the LFM pulse waveform having digital information;
b) an AM/FM signal component validation circuit, in electrical communication with said antenna, for detecting, decoding and validating said AM and FM components in the LFM waveform, and comparing the components to a predetermined criteria, in electrical communication with said antenna;
c) a delay element in electrical communication with the antenna for storing the received LFM pulse waveform;
d) a chopped repeater circuit, in electrical connection with the delay element for encoding the stored LFM pulse waveform in the delay element with a preprogrammed AM and a FM predetermined criteria to form a modified LFM pulse waveform;
e) timing synchronization circuitry for synchronizing the chopped repeater circuit of the modified LFM pulse waveform with reception of the received LFM pulse; and
f) an antenna output circuit, in electrical communication with the chopped repeater circuit, retransmitting of the modified LFM pulse back to the radar source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of decoding and encoding digital information contained within amplitude and frequency modulated components of a received LFM pulse waveforms from a radar source, the method comprising the steps of:
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a) receiving the LFM pulse waveform;
b) detecting the amplitude deviation of the LFM pulse waveform using an AM receiver;
c) detecting frequency deviations in the LFM pulse waveform using an FM receiver;
d) determining if the received demodulated amplitude and frequency deviation components of the LFM pulse waveform satisfies a predetermined criteria;
e) comparing preprogrammed time duration criteria data to the deviation components of the LFM pulse waveform;
f) decoding the digital information in the received LFM waveforms having components that satisfy the time duration criteria;
g) communication of the decoded information to a tag;
h) generating tag transmit data in response to the decoded information;
i) storing the received RF signal for possible retransmission;
j)encoding tag transmit data in the stored RF signal using PM and FM, the deviation components being stored data in a preprogrammed criteria table;
k) chopping the RF signal during transmission; and
l) transmitting the modified LFM pulse waveform in sync with the reception of an LFM pulse waveform with the encoded tag data. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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Specification