Dual mode modulated backscatter system

A radio communication system comprising

• an interrogator including
• means for generating a first modulated signal by modulating a first information signal onto a radio carrier signal, said first information signal indicating which of multiple response modes a receiving tag should respond,
• means for transmitting to said at least one tag during a first time interval said first modulated signal, and transmitting said radio carrier signal during a second time interval,
• said at least one tag including
• means for receiving said radio carrier signal and said first modulated signal,
• means for decoding said first modulated signal to obtain said first information signal,
• backscatter modulator means for modulating the reflection, during said second time interval, of said radio carrier signal using a second information signal whose content, data rate, or modulation is determined from the contents of said first information signal, thereby forming a reflected second modulated signal,
• said interrogator further including
• means for receiving said second modulated signal, and
• means for demodulating said second modulated signal, to obtain said second information signal, whose content, data rate, or modulation was determined from the contents of said first information signal.

A method of operating a radio communication system comprising the steps of

• at an interrogator
• generating a first modulated signal by modulating a first information signal onto a radio carrier signal, said first information signal indicating which of multiple response modes a receiving tag should respond,
• transmitting said first modulated signal to said at least one tag;
• at said at least one tag
• receiving said first modulated signal,
• decoding said first modulated signal to obtain said first information signal,
• modulating, using a backscatter modulator, a reflection of said first modulated signal using a second information signal whose content, data rate, or modulation is determined from the contents of said first information signal, thereby forming a reflected second modulated signal;
• at said interrogator
• receiving said second modulated signal, and
• demodulating said second modulated signal, to obtain said second information signal, whose content, data rate, or modulation was determined from the contents of said first information signal.

A method of operating a radio communication system comprising the steps of

• at an interrogator
• generating a first modulated signal by modulating a first information signal onto a radio carrier signal, said first information signal indicating which of multiple response modes a receiving tag should respond,
• transmitting to said at least one tag during a first time interval said first modulated signal, and transmitting said radio carrier signal during a second time interval;
• at said at least one tag
• receiving said radio carrier signal and said first modulated signal,
• decoding said first modulated signal to obtain said first information signal,
• modulating, using a backscatter modulator, a reflection, during said second time interval, of said radio carrier signal using a second information signal whose content, data rate, or modulation is determined from the contents of said first information signal, thereby forming a reflected second modulated signal;
• at said interrogator
• receiving said second modulated signal, and
• demodulating said second modulated signal, to obtain said second information signal, whose content, data rate, or modulation was determined from the contents of said first information signal.