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US 8,077,763 B2Granted
Full-duplex radio frequency echo cancellation
AssigneeSymbol Technologies, Inc.
InventorsMark Duron, Raj Bridgelall
Life of this patent
Estimating the term…
Abstract
A system comprising a transmitter element creating an interrogation signal and transmitting the interrogation signal and a receiver element receiving a reflection signal of the interrogation signal and combining the reflection signal and a feedback signal to cancel at least a portion of radio frequency echo signals in the reflection signal.
Claims16
A system, comprising:
- a transmitter element creating an interrogation signal and transmitting the interrogation signal;
- and
- a receiver element receiving and demodulating a reflection signal of the interrogation signal and combining the reflection signal and a feedback signal to cancel at least a portion of radio frequency echo signals in the reflection signal, wherein the reflection signal comprises an error component comprising interrogation signal energy reflected from objects in an environment other than a radio frequency tag, and wherein the feedback signal comprises the at least a portion of radio frequency echo signals comprising the error component at lower frequencies than a data signal of interest;
- wherein the feedback signal is derived by isolating the error component of the reflection signal, and wherein the error component of the reflection signal is isolated by low pass filtering the reflection signal.
1 more element
A method, comprising the steps of:
- demodulating a reflection signal into an in-phase signal and a quadrature signal;
- low pass filtering the in-phase signal to isolate an in-phase error signal;
- low pass filtering the quadrature signal to isolate a quadrature error signal;
- modulating the in-phase error signal and the quadrature error signal to create an in-phase feedback signal and a quadrature feedback signal;
- combining the in-phase signal with the in-phase feedback signal and the quadrature signal with the quadrature feedback signal to cancel at least a portion of radio frequency echo signals in the reflection signal;
- and
- band pass filtering each of the combined in-phase signal and in-phase feedback signal and the combined quadrature signal and quadrature feedback signal.
4 more elements
A system, comprising:
- a demodulator to demodulate a reflection signal into an in-phase signal and a quadrature signal;
- a first low pass filter to isolate an in-phase error signal from the in-phase signal;
- a second low pass filter to isolate a quadrature error signal from the quadrature signal;
- a modulator to modulate the in-phase error signal and the quadrature error signal to create a feedback signal;
- a combiner element to combine the in-phase signal with the in-phase feedback signal and the quadrature signal with the quadrature feedback signal to cancel at least a portion of radio frequency echo signals in the reflection signal;
- a first band pass filter to band pass filter the combined in-phase signal and in-phase feedback signal;
- and
- a second band pass filter to band pass filter the combined quadrature signal and quadrature feedback signal.
5 more elements
A system comprising:
- a demodulator to demodulate a reflection signal into an in-phase signal and a quadrature signal;
- a first filter to isolate an in-phase error signal from the in-phase signal;
- a second filter to isolate a quadrature error signal from the quadrature signal;
- a modulator to modulate the in-phase error signal and the quadrature error signal to create a feedback signal;
- a combiner element to combine the reflection signal and the feedback signal to cancel at least a portion of radio frequency echo signals in the reflection signal;
- and
- a sample and hold element that activates a hold mode when a reflection signal is receiving a backscatter signal.
4 more elements
Dependencies are inferred from the claim text.