Communication system, interrogators and communication methods

Abstract

The present invention includes backscatter communication systems, interrogators, methods of communicating in a backscatter system, and backscatter communication methods. According to one aspect of the present invention, a backscatter communication system includes an interrogator including a transmitter configured to output a forward link communication and a receiver configured to receive a return link communication having a carrier signal, the receiver being configured to reduce the amplitude of the carrier signal of the return link communication; and a communication device configured to modulate the carrier signal to communicate the return link communication responsive to reception of the forward link communication.

1. A communication system comprising:
 a communication device configured to receive a continuous wave signal and to output a modulated continuous wave signal responsive to the receiving; and 
 an interrogator configured to reduce an amplitude of a component of the modulated continuous wave signal having a frequency of the continuous wave signal while substantially maintaining an amplitude of another component of the modulated continuous wave signal having another frequency; 
 wherein the interrogator is configured to reduce the amplitude of the component prior to demodulation of the modulated continuous wave signal. 
 
     
     
       2. The system of  claim 1  wherein the communication device is configured to backscatter modulate the continuous wave signal to output the modulated continuous wave signal. 
     
     
       3. The system of  claim 1  wherein the communication device comprises a radio frequency identification device. 
     
     
       4. The system of  claim 1  wherein the interrogator is configured to receive the continuous wave signal and to reduce the amplitude of the component of the modulated continuous wave signal using the continuous wave signal. 
     
     
       5. The system of  claim 1  wherein the interrogator is configured to receive the continuous wave signal and to reduce the amplitude of the component of the modulated continuous wave signal using the continuous wave signal including adjusting at least one of an amplitude and a phase of the continuous wave signal and combining the adjusted continuous wave signal with the modulated continuous wave signal. 
     
     
       6. The system of  claim 5  wherein the modulated continuous wave signal comprises a data portion, and wherein the interrogator is configured to adjust the continuous wave signal before reception of the data portion. 
     
     
       7. The system of  claim 1  wherein the interrogator is configured to receive the continuous wave signal and to reduce the amplitude of the component of the modulated continuous wave signal using the continuous wave signal including matching an amplitude of the continuous wave signal with an amplitude of the modulated continuous wave signal, adjusting a phase of the continuous wave signal, and summing the adjusted continuous wave signal with the modulated continuous wave signal. 
     
     
       8. The system of  claim 1  wherein the interrogator is configured to reduce the amplitude of the component from one non-zero value to another non-zero value less than the one non-zero value. 
     
     
       9. The system of  claim 1  wherein the interrogator is configured to reduce the amplitude of the component prior to quadrature demodulation of the modulated continuous wave signal. 
     
     
       10. An interrogator comprising:
 a receiver configured to receive a continuous wave signal having a frequency and a modulated continuous wave signal, the receiver being further configured to reduce an amplitude of a component of the modulated continuous wave signal having the frequency of the continuous wave signal using the continuous wave signal while substantially maintaining an amplitude of another component of the modulated continuous wave signal having another frequency; 
 wherein the receiver is configured to reduce the amplitude of the component prior to demodulation of the modulated continuous wave signal. 
 
     
     
       11. The interrogator of  claim 10  wherein the receiver is configured to reduce the amplitude of the component of the modulated continuous wave signal using the continuous wave signal including adjusting at least one of an amplitude and a phase of the continuous wave signal and combining the adjusted continuous wave signal with the modulated continuous wave signal. 
     
     
       12. The interrogator of  claim 11  wherein the modulated continuous wave signal comprises a data portion, and wherein the receiver is configured to adjust the continuous wave signal before reception of the data portion. 
     
     
       13. The interrogator of  claim 10  wherein the receiver is configured to reduce the amplitude of the component of the modulated continuous wave signal using the continuous wave signal including matching an amplitude of the continuous wave signal with the amplitude of the modulated continuous wave signal, adjusting a phase of the continuous wave signal, and summing the adjusted continuous wave signal with the modulated continuous wave signal. 
     
     
       14. The interrogator of  claim 10  wherein the receiver is configured to reduce the amplitude of the component from one non-zero value to another non-zero value less than the one non-zero value. 
     
     
       15. The interrogator of  claim 10  wherein the receiver is configured to reduce the amplitude of the component prior to quadrature demodulation of the modulated continuous wave signal. 
     
     
       16. An interrogator comprising:
 a receiver configured to receive a local signal and a communication signal, the receiver being further configured to adjust the local signal responsive to the communication signal and to reduce an amplitude of a component of the communication signal having a first frequency using the adjusted local signal while substantially maintaining an amplitude of another component of the communication signal having another frequency, 
 wherein the local signal comprises a continuous wave signal and the communication signal comprises a modulated continuous wave signal, the receiver being configured to adjust the local signal by matching an amplitude of the local signal with an amplitude of the modulated continuous wave signal and adjusting a phase of the local signal. 
 
     
     
       17. The interrogator of  claim 16  wherein the local signal comprises a continuous wave signal and the communication signal comprises a modulated continuous wave signal. 
     
     
       18. The interrogator of  claim 16  wherein the receiver is configured to adjust the local signal including adjusting at least one of an amplitude and a phase of the local signal and to combine the adjusted local signal and the communication signal to reduce the amplitude of the component of the communication signal having the first frequency. 
     
     
       19. The interrogator of  claim 16  wherein the receiver is configured to adjust the local signal including matching an amplitude of the local signal with an amplitude of the modulated continuous wave signal and adjusting a phase of the local signal. 
     
     
       20. The interrogator of claim  19  16 wherein the receiver is configured to sum the adjusted local signal with the communication signal to reduce the amplitude of the component of the communication signal having the first frequency. 
     
     
       21. The interrogator of  claim 16  wherein the communication signal comprises a data portion and the receiver is configured to adjust the local signal before reception of the data portion. 
     
     
       22. The interrogator of  claim 16  wherein the receiver is configured to reduce the amplitude of the component from one non-zero value to another non-zero value less than the one non-zero value. 
     
     
       23. The interrogator of  claim 16  wherein the receiver is configured to reduce the amplitude of the component prior to demodulation of the modulated continuous wave signal. 
     
     
       24. A communication method comprising:
 communicating a continuous wave signal having a frequency; 
 communicating a modulated continuous wave signal responsive to the continuous wave signal using a communication device, wherein the modulated continuous wave signal is communicated by backscatter modulating the continuous wave signal; 
 receiving the modulated continuous wave signal; and 
 reducing an amplitude of a component of the modulated continuous wave signal having the frequency of the continuous wave signal after the receiving while substantially maintaining an amplitude of a component of the modulated continuous wave signal having a frequency different than the frequency of the continuous wave signal; 
 wherein the reducing comprises reducing prior to demodulation of the modulated continuous wave signal. 
 
     
     
       25. The method of  claim 24  wherein the communicating the modulated continuous wave signal comprises backscatter modulating the continuous wave signal. 
     
     
       26. The method of  claim 24  wherein the communicating comprises communicating using the communication device comprising a radio frequency identification device. 
     
     
       27. The method of  claim 24  further comprising providing a local continuous wave signal and the reducing comprises reducing using the local continuous wave signal. 
     
     
       28. The method of  claim 24  further comprising providing a local continuous wave signal and the reducing comprises reducing using the local continuous wave signal including adjusting at least one of an amplitude and a phase of the local continuous wave signal and combining the adjusted local continuous wave signal and the modulated continuous wave signal. 
     
     
       29. The method of  claim 28  wherein the modulated continuous wave signal comprises a data portion, and the adjusting comprises adjusting before receiving the data portion. 
     
     
       30. The method of  claim 24  further comprising providing a local continuous wave signal and the reducing comprises reducing using the local continuous wave signal including matching an amplitude of the local continuous wave signal with an amplitude of the modulated continuous wave signal, adjusting a phase of the local continuous wave signal, and summing the adjusted local continuous wave signal with the modulated continuous wave signal. 
     
     
       31. The method of  claim 24  wherein the reducing comprises reducing the amplitude of the component from one non-zero value to another non-zero value less than the one non-zero value. 
     
     
       32. The method of  claim 24  wherein the reducing comprises reducing prior to quadrature demodulation of the modulated continuous wave signal. 
     
     
       33. The method of  claim 24  wherein the communicating the continuous wave signal, the receiving and the reducing comprise using an interrogator. 
     
     
       34. A communication method comprising:
 providing a continuous wave signal; 
 modulating the continuous wave signal providing a modulated continuous wave signal to communicate information, wherein the modulating is performed using a radio frequency identification device; 
 receiving the modulated continuous wave signal; and 
 after the receiving, reducing an amplitude of a component of the modulated continuous wave signal having a frequency of the continuous wave signal while substantially maintaining an amplitude of another component of the modulated continuous wave signal having another frequency; 
 wherein the reducing comprises reducing prior to demodulation of the modulated continuous wave signal. 
 
     
     
       35. The method of  claim 34  wherein the modulating comprises backscatter modulating. 
     
     
       36. The method of  claim 34  wherein the modulating comprises modulating using a radio frequency identification device. 
     
     
       37. The method of  claim 34  wherein the reducing comprises adjusting at least one of an amplitude and a phase of the continuous wave signal and combining the adjusted continuous wave signal and the modulated continuous wave signal. 
     
     
       38. The method of  claim 37  wherein the modulated continuous wave signal comprises a data portion and the adjusting comprises adjusting before receiving the data portion. 
     
     
       39. The method of  claim 34  wherein the reducing comprises matching an amplitude of the continuous wave signal with an amplitude of the modulated continuous wave signal, adjusting a phase of the continuous wave signal, and summing the continuous wave signal and the modulated continuous wave signal after the matching and the adjusting. 
     
     
       40. The method of  claim 34  wherein the reducing comprises reducing the amplitude of the component from one non-zero value to another non-zero value less than the one non-zero value. 
     
     
       41. The method of  claim 34  wherein the reducing comprises reducing prior to quadrature demodulation of the modulated continuous wave signal. 
     
     
       42. The method of  claim 34  wherein the providing, the receiving, and the reducing comprise using an interrogator and the modulating comprises using a communication device. 
     
     
       43. A communication method comprising:
 providing a local signal;   receiving a communication signal; and   after the receiving, reducing an amplitude of a first component of the communication signal while substantially maintaining an amplitude of a second component of the communication signal, the reducing comprising adjusting the local signal responsive to the communication signal and combining the communication signal and the local signal after the adjusting.   
     
     
       44. The method of  claim 43  wherein the providing comprises communicating the local signal comprising a continuous wave signal, and further comprising communicating the communication signal comprising a modulated continuous wave signal. 
     
     
       45. The method of  claim 43  further comprising communicating the communication signal using a radio frequency identification device. 
     
     
       46. The method of  claim 43  wherein the reducing comprises adjusting at least one of an amplitude and a phase of the local signal and combining the local signal and the communication signal after the adjusting. 
     
     
       47. The method of  claim 46  wherein the communication signal comprises a data portion and the adjusting comprises adjusting before receiving the data portion. 
     
     
       48. The method of  claim 43  wherein the reducing comprises matching an amplitude of the local signal with an amplitude of the communication signal, adjusting a phase of the local signal, and summing the local signal and the communication signal after the matching and the adjusting. 
     
     
       49. The method of  claim 43  wherein the reducing comprises reducing the amplitude of the first component from one non-zero value to another non-zero value less than the one non-zero value. 
     
     
       50. The method of  claim 43  wherein the reducing comprises reducing prior to demodulation of the modulated continuous wave signal. 
     
     
       51. The method of  claim 43  wherein the providing, the receiving, and the reducing comprise using an interrogator, and further comprising communicating the communication signal using a communication device. 
     
     
       52. A coherent backscatter system communication method comprising:
 reducing an amplitude of a frequency component of a modulated continuous wave signal using a receiver, the reducing including:
 adjusting an amplitude and a phase of a local continuous wave signal providing an adjusted continuous wave signal; and 
 summing the adjusted continuous wave signal with the modulated continuous wave signal. 
   
     
     
       53. A communication system comprising:
 a communication device configured to receive a continuous wave signal and to output a modulated continuous wave signal responsive to the receiving; and 
 an interrogator configured to reduce an amplitude of a component of the modulated continuous wave signal having a frequency of the continuous wave signal while substantially maintaining an amplitude of another component of the modulated continuous wave signal having another frequency; 
 wherein the interrogator is configured to receive the continuous wave signal and to reduce the amplitude of the component of the modulated continuous wave signal using the continuous wave signal including matching an amplitude of the continuous wave signal with an amplitude of the modulated continuous wave signal, adjusting a phase of the continuous wave signal, and summing the adjusted continuous wave signal with the modulated continuous wave signal. 
 
     
     
       54. An interrogator comprising:
 a receiver configured to receive a continuous wave signal having a frequency and a modulated continuous wave signal, the receiver being further configured to reduce an amplitude of a component of the modulated continuous wave signal having the frequency of the continuous wave signal using the continuous wave signal while substantially maintaining an amplitude of another component of the modulated continuous wave signal having another frequency; 
 wherein the receiver is configured to reduce the amplitude of the component of the modulated continuous wave signal using the continuous wave signal including matching an amplitude of the continuous wave signal with the amplitude of the modulated continuous wave signal, adjusting a phase of the continuous wave signal, and summing the adjusted continuous wave signal with the modulated continuous wave signal. 
 
     
     
       55. A communication method comprising:
 communicating a continuous wave signal having a frequency;   communicating a modulated continuous wave signal responsive to the continuous wave signal using a communication device;   receiving the modulated continuous wave signal;   reducing an amplitude of a component of the modulated continuous wave signal having the frequency of the continuous wave signal after the receiving while substantially maintaining an amplitude of a component of the modulated continuous wave signal having a frequency different than the frequency of the continuous wave signal; and   providing a local continuous wave signal and the reducing comprises reducing using the local continuous wave signal including matching an amplitude of the local continuous wave signal with an amplitude of the modulated continuous wave signal, adjusting a phase of the local continuous wave signal, and summing the adjusted local continuous wave signal with the modulated continuous wave signal.   
     
     
       56. A communication method comprising:
 providing a continuous wave signal;   modulating the continuous wave signal providing a modulated continuous wave signal to communicate information;   receiving the modulated continuous wave signal; and   after the receiving, reducing an amplitude of a component of the modulated continuous wave signal having a frequency of the continuous wave signal while substantially maintaining an amplitude of another component of the modulated continuous wave signal having another frequency;   wherein the reducing comprises matching an amplitude of the continuous wave signal with an amplitude of the modulated continuous wave signal, adjusting a phase of the continuous wave signal, and summing the continuous wave signal and the modulated continuous wave signal after the matching and the adjusting.   
     
     
       57. A method comprising:
 transmitting by a transceiver device a wireless spread spectrum signal comprising a wireless command signal;   generating by the transceiver device a local continuous wave signal having a common frequency with a wireless continuous wave signal;   receiving a return signal from a radio frequency communications device using the transceiver device, the return signal comprising a carrier component and a side band component, the carrier component corresponding to the wireless continuous wave signal, the side band component including information from the radio frequency communications device sent in response to the wireless command signal;   adjusting the local continuous wave signal to generate an adjusted local continuous wave signal; and   reducing an amplitude of the carrier component using the adjusted local continuous wave signal and substantially maintaining an amplitude of the side band component, prior to demodulation from the carrier component.    
     
     
       58. The method of claim 57, wherein the adjusting the local continuous wave signal comprises adjusting an amplitude and a phase of the local continuous wave signal.  
     
     
       59. The method of claim 58, wherein the reducing the amplitude of the carrier component comprises summing the return signal with the adjusted local continuous wave signal.  
     
     
       60. The method of claim 59, wherein the transceiver device is configured to communicate in accordance with a selected one of a plurality of RFID communication applications.  
     
     
       61. The method of claim 57, wherein the transceiver device is configured to communicate in accordance with a selected one of a plurality of RFID communication applications.  
     
     
       62. The method of claim 57, wherein the wireless command signal includes a calibration period, a preamble, a start code, and error detection data.  
     
     
       63. The method of claim 62, wherein the information from the radio frequency communications device includes an identification number associated with the radio frequency communications device and error detection data.  
     
     
       64. A system comprising:
 a first radio frequency communications device configured to receive a wireless spread spectrum signal comprising a wireless command signal, and to provide reply information modulated on a wireless continuous wave signal, in response to the wireless command signal; and   a second radio frequency communications device comprising:
 a transmitter to transmit the wireless spread spectrum signal; 
 a first coupler to provide a local continuous wave signal having a common frequency with the wireless continuous wave signal; 
 a receiver to receive a return signal comprising a carrier component and a side band component, the side band component including the reply information from the RFID tag; and 
 circuitry to adjust the local continuous wave signal to generate an adjusted local continuous wave signal according to the return signal received by the receiver, and to reduce an amplitude of the carrier component of the return signal using the adjusted local continuous wave signal while substantially maintaining an amplitude of the side band component, wherein the circuitry comprises a second coupler to sum the return signal with the adjusted local continuous wave signal.  
   
     
     
       65. The system of claim 64, wherein the circuitry comprises an amplitude adjuster to adjust an amplitude of the local continuous wave signal, and a phase shifter to shift a phase of the local continuous wave signal.  
     
     
       66. The system of claim 64, wherein the second radio frequency communications device comprises memory and a microcontroller configured to communicate in accordance with a selected one of a plurality of RFID communication applications.  
     
     
       67. The system of claim 64, wherein the second radio frequency communications device comprises an interrogator having memory and a microcontroller configured to communicate in accordance with a selected one of a plurality of RFID communication applications.  
     
     
       68. A method comprising:
 transmitting a wireless command signal to a first radio frequency communications device from a second radio frequency communications device;   generating, at the second radio frequency communications device, a local continuous wave signal having a common frequency with a wireless continuous wave signal;   receiving a signal using the second radio frequency communications device, the received signal comprising a carrier component and a side band component, the carrier component including the wireless continuous wave signal, the side band component including information modulated on the wireless continuous wave signal by the first radio frequency communications device in response to the command signal;   adjusting at least a phase of the local continuous wave signal to generate an adjusted local continuous wave signal; and   reducing an amplitude of the carrier component relative to an amplitude of the side band component using the adjusted local continuous wave signal, wherein the reducing is performed prior to demodulation from the carrier component.    
     
     
       69. The method of claim 68, wherein the adjusting of the phase of the local continuous wave signal is according to the received signal.  
     
     
       70. The method of claim 68, wherein the reducing comprises summing the received signal with the adjusted local continuous wave signal.  
     
     
       71. The method of claim 68, wherein the wireless command signal comprises a wireless spread spectrum signal; and the side band component includes an identification number of the first radio frequency communications device.