Method and apparatus for transmitting a signal by a radio frequency identification reader

• US 9,501,673 B2
• Filed: 12/31/2013
• Issued: 11/22/2016
• Est. Priority Date: 12/31/2013
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Inventors: Dorevitch, Joshua E, Gabato, Manuel Jr., Stengel, Robert E.
• Primary Examiner(s): Zhao, Wei
• Application Number:
  US14/145,261
• Publication Number:
  US 20150186692A1
• Time in Patent Office: 1,057 Days
• Field of Search: 370/311
• US Class Current: 1/1
• CPC Class Codes: G06K 2007/10495 Circuits for pulse forming, amplifying
• CPC Class Codes: G06K 7/10009 sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves

Abstract

A Radio Frequency Identification (RFID) reader is provided that receives a digital input signal, converts the digital input signal to an analog input signal, and determines whether the digital input signal is an unmodulated signal or is modulated with information. When the digital input signal is modulated with information, the RFID reader filters the analog input signal to produce a filtered analog input signal and transmits the filtered signal. When the digital input signal is an unmodulated signal, the RFID reader bypasses the filtering of the analog input signal to produce an unfiltered analog input signal and transmits the unfiltered analog input signal.

Claims

1. A method for transmitting a signal by a Radio Frequency Identification (RFID) reader, the method comprising:

receiving a digital input signal;

converting the digital input signal to an analog input signal;

determining whether the digital input signal is an unmodulated signal or is modulated with information;

when the digital input signal is modulated with information, filtering the analog input signal to produce a filtered signal and transmitting the filtered signal; and

when the digital input signal is an unmodulated signal, bypassing the filtering of the analog input signal to produce an unfiltered analog input signal and transmitting the unfiltered analog input signal;

wherein the digital input signal comprises an in-phase baseband component and a quadrature-phase baseband component;

wherein converting the digital input signal to an analog input signal comprises converting the in-phase baseband component to an analog in-phase signal and converting the quadrature-phase baseband component to an analog quadrature-phase signal;

wherein filtering the analog input signal to profuce a filtered signal and transmitting the filtered signal comprises;

filtering the analog in-phase signal to produce a filtered analog in-phase signal;

filtering the analog quadrature-phase signal to produce a filtered analog quadrature-phase signal;

combining the filtered analog in-phase signal and the filtered analog quadrature-phase signal to produce a combined signal; and

transmitting the combined signal.

2. The method of claim 1, wherein filtering comprises filtering the analog input signal with an anti-aliasing filter.

3. The method of claim 2, wherein bypassing the filtering of the analog input signal comprising switching the anti-aliasing filter out of the path of the analog signal.

4. The method of claim 1, wherein transmitting the filtered signal comprises:

upconverting the filtered signal to produce a low power radio frequency (RF) signal;

amplifying the low power RF signal to produce an output signal; and

transmitting the output signal.

5. The method of claim 1, wherein transmitting the unfiltered analog input signal comprises:

upconverting the unfiltered analog input signal to a transmission frequency to produce a low power radio frequency (RF) signal;

amplifying the low power RF signal to produce an output signal; and

transmitting the output signal.

6. The method of claim 1, wherein filtering the analog in-phase signal to produce a filtered analog in-phase signal comprises switching a first filter into a path of the analog in-phase signal and wherein filtering the analog quadrature-phase signal to produce a filtered analog quadrature-phase signal comprises switching a second filter into a path of the analog quadrature-phase signal.

7. The method of claim 1,

wherein the digital input signal comprises an in-phase baseband component and a quadrature-phase baseband component;

wherein converting the digital input signal to an analog input signal comprises converting the in-phase baseband component to an analog in-phase signal and converting the quadrature-phase baseband component to an analog quadrature-phase signal;

wherein bypassing the filtering of the analog input signal to produce an unfiltered analog input signal and transmitting the unfiltered analog input signal comprises;

bypassing a filtering of the analog in-phase signal to produce an unfiltered analog in-phase signal;

bypassing a filtering of the analog quadrature-phase signal to produce an unfiltered analog quadrature-phase signal;

combining the unfiltered analog in-phase signal and the unfiltered analog quadrature-phase signal to produce a combined signal; and

transmitting the combined signal.

8. The method of claim 7, wherein bypassing a filtering of the analog in-phase signal comprises switching a first bypass circuit into a path of the analog in-phase signal, thereby bypassing a filtering of the analog in-phase signal, and wherein bypassing a filtering of the analog quadrature-phase signal comprises switching a second bypass circuit into a path of analog quadrature-phase signal, thereby bypassing a filtering of the analog quadrature-phase signal.

9. A Radio Frequency Identification (RFID) reader comprising:

a processor that is configured to produce a digital input signal and to determine whether the digital input signal is an unmodulated signal or is modulated with information;

transmitter circuitry that is configured to transmit a wireless signal, wherein the transmitter circuitry is configured to;

receive the digital input signal;

convert the digital input signal to an analog input signal;

when the digital input signal is modulated with information, filter the analog input signal to produce a filtered analog input signal and transmit the filtered signal; and

when the digital input signal is an unmodulated signal, bypass the filtering of the analog input signal to produce an unfiltered analog input signal and transmit the unfiltered analog input signal;

wherein the digital input signal comprises an in-phase baseband component and a quadrature-phase baseband component and wherein the transmitter circuitry comprises;

a first digital to analog converter (D/A) that is configured to convert the in-phase baseband component to an analog in-phase signal;

a second D/A that is configured to convert the quadrature-phase baseband component to an analog quadrature-phase signal;

a first filter that is configured to filter the analog in-phase signal to produce a filtered analog in-phase signal;

a second filter that is configured to filter the analog quadrature-phase signal to produce a filtered analog quadrature-phase signal;

a signal combiner that is configured to combine the filtered analog in-phase signal and the filtered analog quadrature-phase signal to produce a combined signal; and

wherein the transmitter circuitry is configured to transmit the combined signal.

10. The RFID reader of claim 9, wherein the processor is configured to:

when the digital input signal is an unmodulated signal, produce a first plurality of control signals that cause the transmitter circuitry to bypass the filtering of the analog input signal to produce an unfiltered analog input signal; and

when the digital input signal is modulated with information, produce a second plurality of control signals that cause the transmitter circuitry to filter the analog input signal to produce a filtered signal.

11. The RFID reader of claim 10, wherein the transmitter circuitry comprises:

one or more bypass circuits;

one or more filters;

a plurality of switches coupled to each of the one or more bypass circuits and the one or more filters;

wherein, in response to receiving the first plurality of control signals, the plurality of switches couple the one or more bypass circuits into a path of the analog input signal; and

wherein, in response to receiving the second plurality of control signals, the plurality of switches couple the one or more filters into a path of the analog input signal.

12. The RFID reader of claim 11, wherein the one or more filters are anti-aliasing filters.

13. The RFID reader of claim 9, wherein the transmitter circuitry comprises:

one or more modulators that are configured to upconvert the filtered signal to produce a low power radio frequency (RF) signal;

a power amplifier that is configured to amplify the low power RF signal to produce an output signal; and

wherein the transmitter circuitry transmits the output signal.

14. The RFID reader of claim 9, wherein the transmitter circuitry comprises:

one or more modulators that are configured to upconvert the unfiltered analog input signal to a transmission frequency produce a low power radio frequency (RF) signal;

a power amplifier that is configured to amplify the low power RF signal to produce an output signal; and

wherein the transmitter circuitry is configured to transmit the output signal.

15. The RFID reader of claim 9, wherein the processor is configured to:

control a switching of the first filter into a path of the analog in-phase signal; and

control a switching of the second filter into a path of the analog quadrature-phase signal.

16. The RFID reader of claim 9, wherein the digital input signal comprises an in-phase baseband component and a quadrature-phase baseband component and wherein the transmitter circuitry comprises:

a first digital to analog converter (D/A) that is configured to convert the in-phase baseband component to an analog in-phase signal;

a second D/A that is configured to convert the quadrature-phase baseband component to an analog quadrature-phase signal;

a first bypass circuit that is configured to bypass a filtering of the analog in-phase signal, thereby producing an unfiltered analog in-phase signal;

a second bypass circuit that is configured to bypass a filtering of the analog quadrature-phase signal, thereby producing an unfiltered analog quadrature-phase signal;

a signal combiner that is configured to combine the bypass analog in-phase signal and the bypass analog quadrature-phase signal to produce a combined signal; and

wherein the transmitter circuitry is configured to transmit the combined signal.

17. The RFID reader of claim 16, wherein the processor is configured to:

control a switching of the first bypass circuit into a path of the analog in-phase signal; and

control a switching of the second bypass circuit into a path of the analog quadrature-phase signal.