Patent Publication Number: US-2018052221-A1

Title: RF ID Verifier

Description:
FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT 
     The United States Government has ownership rights in this invention. Licensing inquiries may be directed to Office of Research and Technical Applications, Space and Naval Warfare Systems Center, Pacific, Code 72120, San Diego, Calif., 92152; telephone (619) 553-5118; email: ssc_pac_t2@navy.mil. Reference Navy Case No. 102,681. 
    
    
     BACKGROUND OF THE INVENTION 
     Radar has long been utilized to detect object parameters (e.g. distance, speed, direction, etc.), in addition to analyzing weather and geological systems. Using electromagnetic radio waves, these systems are used for line-of-sight transmission and detection. Traditional systems utilize an antenna to emit the radio wave, which is reflected off of objects and returned to the transmitter. Changes in radio wave parameters, such as phase, frequency and amplitude can be used to determine characteristics of the reflecting object. 
     Radio waves can also be used to transmit and receive data, such as in frequency-modulated systems like FM radio, whereby a station transmits data that is received by a secondary receiver, such as a car antenna. In contrast to the previously described system, which utilizes a separate transmitter and receiver, it is also possible to embed information into otherwise passively reflected radio waves. For example, a single transceiver may transmit a radio wave that is reflected from a plane and back to the original transceiver. In traditional systems, the reflected radio wave could be used to determine distance, speed and direction. Modern systems can also be equipped to embed data into the reflected signal. Using the example of the plane, a system on the plane could actively modulate and alter the reflected signal, whereby the transceiver would receive a modified radio wave. Similar to Morse code, the embedded signal could be demodulated at the transceiver, thereby allowing the plane to communicate with the transmission station. 
     The present invention is intended to verify functionality of the reflector and modulator systems. 
     SUMMARY OF THE INVENTION 
     An aspect of the present invention is drawn to a device for use with a modulator and radar reflector, the modulator being operable to generate a modulation signal, the radar reflector being operable to generate a reflected radar signal based on the modulation signal and a radar signal. The device includes: a radar transmitter operable to transmit the radar signal; a radar receiver operable to receive the reflected radar signal; an oscilloscope operable to generate a received signal based on the reflected radar signal; and an output component operable to output an output signal based on the received signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and form a part of the specification, illustrate example embodiments and, together with the description, serve to explain the principles of the invention. In the drawings: 
         FIG. 1  illustrates an example prior art radar system: 
         FIG. 2  illustrates an example radar system enabled for communication; 
         FIG. 3  illustrates an example system to detect, modify and verify a radar signal; 
         FIG. 4  illustrates an example verifier system; and 
         FIG. 5  illustrates an example system to externally validate signal modification. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the invention verify, in a portable manner, the functionality of energy reflecting devices. 
     A device is designed to verify the functioning of radar reflectors. It includes a radar and a demodulator. Specifically, the radar is a tunable continuous wave (CW) homodyne radar that can verify the operation of reflectors in selected frequencies of the X and Ku band. The radar receives signal through an antenna. It demodulates the received signal and displays it on its built-in oscilloscope. 
     A single local oscillator generates a sinusoid at a selected frequency. The local oscillator has a multiplier to generate and amplify a plurality of selectable frequencies in the Ku band. Low-band frequencies are amplified by a low-noise amplifier. The selected signal is transmitted through the antenna to the reflector. The reflector is an active device that can reflect a modulated radar signal based on a modulation scheme provided by a modulator at the reflector. The reflected, modulated signal is received through the same antenna that transmitted the original signal. The received modulated reflected signal is fed to the detector circuit for amplitude adjustment and demodulation. Demodulated signal is then displayed on the oscilloscope. 
     Before a system of the present invention is discussed, prior art radar systems will be discussed to provide background. 
     Prior art and conventional radar systems will now be described with reference to  FIGS. 1-2 . 
       FIG. 1  illustrates an example prior art radar system. 
     As shown in the figure, the radar system includes a ground transceiver  102  and a plane  104 . 
     Ground transceiver  102  is arranged to communicate with plane  104  by way of a radar communication channel  120 . Plane  104  is arranged to communicate with ground transceiver  102  by way of a radar communication channel  122 . 
     Ground transceiver  102  may be any device or system that is operable to generate and receive radar signals. Non-limiting examples of transmission systems include parabolic and phased array transmitters, and associated receivers operating at a frequency between 3 MHz and 100 GHz. 
     In operation, ground transceiver  102  may transmit radar signals and receive reflected signals used, for example, to detect the presence of unknown objects or track objects. Communication channel  120  represents the transmitted signal and communication channel  122  represents a passively reflected signal that is then received by ground transceiver  102 . 
     It has been previously demonstrated that reflected radar signal could additionally be utilized for communication by modulating the otherwise passive reflection. With modulation, data could be embedded into the reflected signal. This will be described with additional reference to  FIG. 2 . 
       FIG. 2  illustrates an example radar system enabled for communication. 
     As shown in the figure, the system includes a ground transceiver  202  and a plane  204 . Ground transceiver  202  additionally includes a demodulator  206 . Plane  204  additionally includes a reflector  208  and a modulator  210 . 
     Ground transceiver  202  is arranged adjacent to and in communication with demodulator  206 . Reflector  208  and modulator  210  are arranged on plane  204 . Reflector  208  is arranged adjacent to and in communication with modulator  210 . Ground transceiver  202  is arranged to communicate with plane  204  by way of a radar communication channel  220 . Plane  204  is arranged to communicate with ground transceiver  202  by way of a radar communication channel  222 . 
     Ground transceiver  202  may be any device or system that is operable to generate and receive radar signals. Non-limiting examples of transmission systems include parabolic and phased array transmitters and associated receivers operating at a frequency between 3 MHz and 100 GHz. 
     Demodulator  206  may be any device or system that is operable to detect modifications to the signal generated by ground transceiver  202 . 
     Reflector  208  may be any device or system that is operable to reflect a radar signal. 
     Modulator  210  may be any device or system that is operable to modify a radar signal in combination with reflector  208 . Non-limiting examples of signal modification may include changes to the frequency, wavelength, amplitude, pulse repetition or pulse length. 
     In operation, ground transceiver  202  may transmit radar signals and receive reflected signals used, for example, to detect the presence of unknown objects, track objects, or transmit data to an ancillary system. Communication channel  220  represents the transmitted signal and communication channel  222  represents both the passively and actively reflected signal that is then received by ground transceiver  202 . Stimulated by modulator  210 , reflector  208  may modify the radar signal in order to embed data in the transmission. Ground transceiver  202  may then detect the reflected signal, which is then processed by demodulator  206  to detect any information embedded in the signal. 
     Given the common use of radar systems, embedding data into a reflected signal provides an additional communication channel with little cost. These systems could increase the available modes of communication and utilize different infrastructure. Increased redundancy of communication systems may reduce the opportunity for communication failures. 
     Despite the current use of communication systems utilizing reflected radar, there is no easy method to verify reflector functionality. With reference to  FIG. 2 , reflector  208  or modulator  210  may degrade with time and use, and this degradation could negatively affect functionality, decreasing the signal-to-noise ratio or otherwise compromising effective data transmission. Current systems to validate reflectors are not portable and require bench-top measurements. This prevents testing reflectors in the field. A portable system to verify reflector operation is needed. 
     Aspects of the present invention provide a system and method to portably verify a reflector. 
     The verifier is a portable device enabled to transmit and receive radio signals, demodulate signals, and output signals to an external device. In operation, the verifier would transmit a radio signal using an antenna, which would be modulated and reflected by a reflector being tested. Upon receiving the reflected radio signal, the verifier demodulates the signal. For portable screening, an internal oscilloscope could be used to display the demodulated signal for comparison against expectation. Further verification can be conducted by using an external oscilloscope. The verifier can output the demodulated signal, and the modulator of the reflecting device can output the modulation signal; an external oscilloscope can be used to display and compare both signals concurrently. 
     Aspects of the present invention will be further described with reference to  FIGS. 3-5 . 
       FIG. 3  illustrates an example system to detect, modify and verify a radar signal. 
     As shown in the figure, the system includes a verifier  302 , a reflector  304  and an oscilloscope  306 . Verifier  302  additionally includes a verifier display  308 , a verifier transmitter  310 , a verifier receiver  312 , a verifier output  314  and a frequency selector  316 . Reflector  304  additionally includes a reflecting component  318 , a reflector output  320  and a modulator  322 . Oscilloscope  306  additionally includes an oscilloscope display  324 . 
     Verifier display  308  and frequency selector  316  are arranged in view on the enclosure of verifier  302 , whereas verifier transmitter  310 , verifier receiver  312  and verifier output  314  may be arranged within the enclosure of verifier  302 . Verifier  302  is arranged to communicate with reflector  304  by way of a radar communication channel  330  and a radar communication channel  332 . In particular, verifier transmitter  310  is arranged to communicate to reflecting component  318  by communication channel  330 , whereas reflecting component  318  is arranged to communicate to verifier receiver  312  by communication channel  332 . Reflecting component  318 , reflector modulator  322  and reflector output  320  are arranged within the enclosure of reflector  304 . Reflecting component  318  is arranged to communicate with modulator  322  by way of communication channel  336 . Modulator  322  is further arranged to communicate with reflecting component  318  by way of communication channel  338  and with reflector output  320  by way of communication channel  340 . Additionally, verifier output  314  is arranged to communicate with oscilloscope  306  by way of communication channel  334 , whereas reflector output  320  is arranged to communicate with oscilloscope  306  by way of communication channel  342 . 
     Verifier transmitter  310  may be any device or system operable to generate and transmit a radar signal. Verifier receiver  312  may be any device or system operable to receive a radar signal. Non-limiting examples include parabolic and phased array transmitters and associated receivers operating at a frequency between 3 MHz and 100 GHz. Frequency selector  316  is utilized to select the transmission band used in operation. 
     Although verifier  302  is identified to include verifier transmitter  310  and verifier receiver  312  separately, in some embodiments verifier transmitter  310  and verifier receiver  312  may be a single transceiver. 
     Verifier output  314  may be any device or system to that enables verifier  302  to output a signal to an ancillary device. Non-limiting examples of verifier output  314  include wired systems such as fiber optic and copper cabling or wireless transmission systems such as Wi-Fi and Bluetooth. 
     Verifier display  308  may be any device or system to provide visual representation of the data. 
     Reflecting component  318  may be any device or system operable to receive and modulate a radar signal based on stimulating voltage provided by modulator  322 . 
     Modulator  322  may be any device or system that is operable to modify the characteristics of a radar signal to relay data. Non-limiting examples of signal modification may include changes to the frequency, wavelength, amplitude, pulse repetition or pulse length. 
     Reflector output  320  may be any device or system that enables reflector  304  to output a signal to a separate device. Non-limiting examples of reflector output  320  include wired systems such as fiber optic and copper cabling or wireless transmission systems such as Wi-Fi and Bluetooth. 
     Oscilloscope  306  is enabled to receive signals and graphically display them on oscilloscope display  324 . 
     A more detailed discussion of verifier  302  will now be described with additional reference to  FIG. 4 . 
       FIG. 4  illustrates an exploded view of verifier  302 . 
     As shown in the figure, verifier  302  includes verifier display  308 , verifier transmitter  310 , verifier receiver  312 , verifier output  314  and frequency selector  316 . Verifier  302  additionally includes a demodulator  402 . Verifier display  308  additionally includes a demodulated signal  404 . 
     Verifier display  308  and frequency selector  316  are arranged in view on the enclosure, whereas demodulator  402  may be arranged within the enclosure of verifier  302 . Verifier receiver  312  is arranged in communication with demodulator  402  by way of communication channel  412 . Demodulator  402  is arranged in communication with verifier output  314  and verifier display  308  by way of communication channels  414  and  416 . In particular, demodulator  402  is arranged to communicate to verifier display  308  by way of communication channel  414  and demodulator  402  is arranged to communicate with verifier output  314  by way of communication channel  416 . Verifier transmitter  310  is arranged in communication with verifier display  308  by way of communication channel  410 . 
     Frequency selector  316  may be any device or system used to allow an operator to adjust transmission frequencies of verifier  302  as required for testing. 
     Demodulator  402  may be any device or system that is operable to detect modifications to the signal generated by verifier transmitter  310  and reflected by reflector  304 . 
     In operation, verifier transmitter  310  generates a radar signal based on frequency determined by frequency selector  316 . 
     Returning to  FIG. 3 , and in operation as a non-communicating system, reflector  304  would reflect radar energy passively and without modulation. Upon engaging modulator  322 , reflector  304  would produce a modulated radar signal with embedded information. Modulator  322  provides the driving voltage to reflector  304 , enabling signal modulation and the embedding of data within radar communication channel  332 . Non-limiting examples of signal modification include changes to frequency, wavelength, amplitude, pulse repetition, or pulse length. 
     Returning to  FIG. 4 , verifier receiver  312  would then receive the modulated and reflected radar signal. Demodulator  402  would then determine the presence of any signal modifications. Verifier display  308  may be used to display the demodulated signal  404 . While not shown, verifier display  308  may also be enabled to show the transmitted and as-received signals without demodulation for additional validation. Using frequency selector  316 , an operator may adjust transmission signal characteristics in accordance to testing requirements. Additionally, the original verifier transmission signal, reflected signal, and demodulated signal may be output to an external device by way of verifier output  314 . 
     Returning to  FIG. 3 , reflector  304  may output the signal from modulator  322  using reflector output  320 . 
     In this way, verifier  302  may be used independently or in conjunction with an external device such as oscilloscope  306  to validate operation. Oscilloscope  306  may be used to verify the functionality of verifier  302  by comparing the demodulated signal with that from reflector  304 . A more detailed discussion of oscilloscope  306  will now be described with additional reference to  FIG. 5 . 
       FIG. 5  illustrates an example system to externally validate signal modification. 
     As shown in the figure, the system includes oscilloscope  306  and oscilloscope display  324 . Oscilloscope  306  additionally includes a dial bank  502 . Oscilloscope display  324  additionally includes a modulator signal  504  and a verifier signal  506 . 
     Oscilloscope display  324  and dial bank  502  are arranged in view on the enclosure of oscilloscope  306 . Modulator signal  504  and verifier signal  506  are arranged within oscilloscope display  324 . 
     Dial bank  502  includes a plurality of dials enabled to control oscilloscope display  324 . 
     In operation, oscilloscope display  324  may be used to monitor signals of both verifier  302  and reflector  304 . For example, oscilloscope display may be configured to display modulator signal  504  from reflector  304  in conjunction with demodulated verifier signal  506  from verifier  302 . In a given configuration, oscilloscope display  324  may graphically display these signals, whereby modulator signal  504  from modulator  322  has similar frequency, amplitude and pulse frequency comparable to the demodulated verifier signal  506  from verifier  302 . In this example, the system is operating correctly. Alternatively, if reflector  304  or components therein were not operating correctly, these two signals would not be comparable, and would demonstrate device failure. 
     In summary, the described invention provides a basis to improve reflector testing. Previous systems used laboratory-based equipment, requiring bench top measurements and were not portable. This limitation reduced or prevented the opportunity to verify reflector functionality in the field. The current disclosure describes a system equipped to validate reflector function using a portable device with a built-in oscilloscope and versatile frequency band options. The system additionally allows testing with an auxiliary oscilloscope, enabling a user to validate the radar testing equipment. 
     The foregoing description of various preferred embodiments have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The example embodiments, as described above, were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.