Microwave noncontact identification transponder using subharmonic interrogation and method of using the same
First Claim
Patent Images
1. An improvement in a contactless transponder having a modulation oscillator, a quasi-optical mixer having a first input coupled to said modulation oscillator and an antenna having an input coupled to an output of said mixer comprising:
- an identification code generator coupled to a second input of said mixer, wherein said mixer modulates an interrogation signal received by said antenna having a frequency, fi, with a data carrier signal having a frequency, fd, generated by said modulation oscillator to transmit supressed-carrier double sideband response signals, wherein each sideband response signal is modulated by an identification code generated by said identification code generator, said data frequency, fd, being at a nonharmonic value of said interrogation frequency, fi,whereby false detection arising from reflections of transmitted harmonics of said interrogation signal is avoided.
1 Assignment
0 Petitions
Accused Products
Abstract
A credit-card sized microwave transponder for "wireless key" and surveillance applications uses a subharmonically-pumped quasi-optical mixer. The transponder is activated by a C-band interrogation beam to upconvert and radiate a digitally modulated identification tone at X-band frequencies nonharmonically related to the interrogation signal.
-
Citations
20 Claims
-
1. An improvement in a contactless transponder having a modulation oscillator, a quasi-optical mixer having a first input coupled to said modulation oscillator and an antenna having an input coupled to an output of said mixer comprising:
-
an identification code generator coupled to a second input of said mixer, wherein said mixer modulates an interrogation signal received by said antenna having a frequency, fi, with a data carrier signal having a frequency, fd, generated by said modulation oscillator to transmit supressed-carrier double sideband response signals, wherein each sideband response signal is modulated by an identification code generated by said identification code generator, said data frequency, fd, being at a nonharmonic value of said interrogation frequency, fi, whereby false detection arising from reflections of transmitted harmonics of said interrogation signal is avoided. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. An improvement in a contactless transponder having a modulation oscillator, a quasi-optical mixer having a first input coupled to said modulation oscillator and an antenna having an input coupled to an output of said mixer comprising:
an identification code generator coupled to a second input of said mixer, wherein said modulation oscillator generates a plurality of data carrier signals, wherein said mixer modulates an interrogation signal received by said antenna having a frequency, fi, with said plurality of data carrier signal each having a frequency, fdi, generated by said modulation oscillator to transmit supressed-carrier double sideband response signals, wherein each of said plurality of sideband response signals is modulated by an identification code generated by said identification code generator. - View Dependent Claims (11, 12)
-
13. A method for providing an identification response to an interrogation signal comprising:
-
generating a data carrier signal having a frequency, fd ; modulating said data carrier signal with an identification code; receiving an interrogation signal having a frequency, fi ; mixing said modulated data signal at frequency, fd, and interrogation signal at frequency, fi, to obtain a suppressed-carrier double sideband modulated response signal, whereby a reliably detectable response signal is generated in said transponder. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
-
Specification