HDX DEMODULATOR

• US 20110210823A1
• Filed: 10/12/2010
• Published: 09/01/2011
• Est. Priority Date: 10/09/2009
• Status: Active Grant

• Current Assignee: Allflex Australia Pty. Ltd. (Merck & Co., Inc.)
• Original Assignee: Aleis Pty. Ltd. (Merck & Co., Inc.)
• Inventors: Bateman, Leigh
• Granted Patent: US 8,811,542 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

Low noise mixers for use in RFID readers and RFID readers configured to receive data from ISO HDX transponders in accordance with embodiments of the invention are illustrated. One embodiment of the invention receives the HDX FSK signal using a resonant antenna, upwardly mixes the FSK signal to an intermediate frequency, filters the intermediate frequency FSK signal using at least one ceramic bandpass filter, and demodulates the filtered intermediate frequency FSK signal to produce a binary output.

Claims

1. A process for demodulating a low frequency HDX FSK signal, comprising:

receiving the HDX FSK signal using a resonant antenna;

upwardly mixing the FSK signal to an intermediate frequency;

filtering the intermediate frequency FSK signal using at least one ceramic bandpass filter; and

demodulating the filtered intermediate frequency FSK signal to produce a binary output.

2. The process of claim 1, wherein upwardly mixing the FSK signal to an intermediate frequency comprises mixing the FSK signal with a local oscillator frequency.

3. The process of claim 1, wherein filtering the intermediate frequency FSK signal using at least one ceramic bandpass filter comprises:

filtering the intermediate frequency FSK signal using a first ceramic bandpass filter;

providing the filtered signal to a first intermediate frequency amplifier;

filtering the output of the first intermediate frequency amplifier with a second ceramic bandpass filter; and

providing the output of the second ceramic bandpass filter to a second intermediate frequency amplifier.

4. The process of claim 1, wherein demodulating the filtered intermediate frequency FSK signal to produce a binary output comprises:

reducing the frequency of the filtered intermediate frequency FSK signal using a frequency divider; and

providing the reduced frequency filtered FSK signal to a microcontroller configured to demodulate the reduced frequency FSK signal and detect binary data.

5. The process of claim 1, wherein the HDX FSK frequencies are 134.2 KHz and 124.2 KHz.

6. The process of claim 5, wherein the HDX FSK frequencies are upwardly mixed to a center frequency of 450 KHz.

7. The process of claim 5, wherein the at least one ceramic bandpass filter has a 6 dB width of at least +/−

10 KHz on either side of the center frequency of the intermediate frequency signal.

8. The process of claim 7, wherein the at least one ceramic bandpass filter has a 6 dB width of at least +/−

13 KHz on either side of the center frequency of the intermediate frequency signal.

9. The process of claim 8, wherein the at least one ceramic bandpass filter has a 6 dB width of +/−

13 KHz on either side of the center frequency of the intermediate frequency signal.

10. An RFID receiver, comprising:

a resonant antenna configured to receive an FSK signal from an HDX transponder;

a mixer configured to upwardly mix an FSK signal received via the resonant antenna to an intermediate frequency;

at least one ceramic filter configured to bandpass filter the intermediate frequency FSK signal;

at least one intermediate frequency amplifier configured to amplify the filtered frequency intermediate FSK signal; and

a demodulator configured to demodulate the filtered intermediate frequency FSK signal and detect binary data.

11. The RFID receiver of claim 10, wherein:

a first ceramic filter is configured to receive an intermediate frequency signal from the mixer, where the first ceramic filter includes an output connected to the input of a first intermediate frequency amplifier;

a second ceramic filter is configured to receive an intermediate frequency signal from the first intermediate frequency amplifier, where the second ceramic filter includes an output connected to the input of a second intermediate frequency amplifier; and

the second intermediate frequency amplifier is configured to provide the filtered intermediate frequency FSK signal to the demodulator.

12. The RFID reader of claim 10, wherein:

the demodulator comprises;

a microcontroller; and

a frequency divider configured to reduce the frequency of the FSK demodulator to a lower intermediate frequency and to provide the lower intermediate frequency FSK signal to the micro controller;

wherein the microcontroller is configured to demodulate the lower intermediate frequency FSK signal to detect binary data; and

the mixer is configured to use a local oscillator frequency generated using the microcontroller to upwardly mix the FSK signal received via the resonant antenna.

13. The RFID reader of claim 10, wherein the resonant antenna is configured to receive HDX FSK frequencies of 134.2 KHz and 124.2 KHz.

14. The RFID reader of claim 13, wherein the HDX FSK frequencies are upwardly mixed to a center frequency of 450 KHz.

15. The RFID reader of claim 13, wherein the at least one ceramic filter has a 6 dB width of at least +/−

10 KHz on either side of the center frequency of the intermediate frequency signal.

16. The RFID reader of claim 15, wherein the at least one ceramic filter has a 6 dB width of at least +/−

13 KHz on either side of the center frequency of the intermediate frequency signal.

17. The RFID reader of claim 16, wherein the at least one ceramic filter has a 6 dB width of +/−

13 KHz on either side of the center frequency of the intermediate frequency signal.