RFID receiver and method of extracting data bits encoded in a radio signal

1. An RFID receiver, comprising:

an antenna configured to receive a radio signal from an RFID transmitter, and to generate an electrical signal from the radio signal received from the RFID transmitter; and

a decoder circuit connected to the antenna and configured to extract from the electrical signal generated by the antenna data bits encoded in the electrical signal; wherein the decoder circuit comprises:

an analog-to-digital converter connected directly to the antenna and configured to generate a digital input signal from the electrical signal generated by the antenna, and

a bit extractor connected to the analog-to-digital converter and configured to extract the data bits from the digital input signal generated by the analog-to-digital converter,

wherein the bit extractor comprises a pulse extractor configured to extract sub-bit pulses from the digital input signal generated by the analog-to-digital converter, and a bit detector configured to detect data bits in the sub-bit pulses, the bit extractor comprising a sub-sampling module configured to sample the sub-bit pulses extracted by the pulse extractor at a reduced sampling rate which is lower than the sampling rate used by the analog-to-digital converter to generate the digital signal.

2. The RFID receiver of claim 1 , wherein the bit extractor comprises a low pass filter configured to extract sub-bit pulses from the digital input signal generated by the analog-to-digital converter.

3. The RFID receiver of claim 2 , wherein the low pass filter is implemented as a moving average filter.

4. The RFID receiver of claim 1 , wherein the pulse extractor comprises a moving average filter configured to generate the sub-bit pulses from unfiltered sub-bit pulses of the digital signal.

5. The RFID receiver of claim 4 , wherein the pulse extractor further comprises a low pass filter arranged downstream of the pulse extractor's moving average filter.

6. The RFID receiver of claim 1 , wherein the bit extractor is configured to generate a moving decision threshold for determining data bits from the sub-bit pulses.

7. The RFID receiver of claim 1 , wherein the analog-to-digital converter comprises an electronic circuit configured to generate the digital input signal from the electrical signal generated by the antenna; and the electronic circuit is connected to the antenna through a diode-free electrical connection.

8. The RFID receiver of claim 1 , wherein the bit extractor comprises a processor and computer program code configured to direct the processor to extract the data bits from the digital input signal generated by the analog-to-digital converter.

9. The RFID receiver of claim 1 , wherein the antenna is configured to receive a radio signal from an RFID transmitter of an RFID transponder, and to generate an electrical signal from the radio signal received from the RFID transmitter of the RFID transponder.

10. A method of extracting data bits encoded in a radio signal received from an RFID transmitter, the method comprising:

generating in an antenna of an RFID receiver an electrical signal from the radio signal received from the RFID transmitter;

connecting directly to the antenna an analog-to-digital converter;

generating in the analog-to-digital converter a digital input signal from the electrical signal generated by the antenna;

connecting a bit extractor to the analog-to-digital converter; and

extracting by the bit extractor the data bits from the digital input signal generated by the analog-to-digital converter;

wherein extracting by the bit extractor the data bits from the digital input signal comprises:

extracting by a pulse extractor sub-bit pulses from the digital input signal;

detecting by a bit detector data bits in the sub-bit pulses; and

sampling by a sub-sampling module the sub-bit pulses extracted by the pulse extractor at a reduced sampling rate which is lower than the sampling rate used by the analog-to-digital converter to generate the digital signal.

11. An RFID receiver, comprising:

an antenna configured to receive a radio signal from an RFID transmitter, and to generate an electrical signal from the radio signal received from the RFID transmitter; and

a decoder circuit connected to the antenna and configured to extract from the electrical signal generated by the antenna data bits encoded in the electrical signal; wherein the decoder circuit comprises:

an analog-to-digital converter connected directly to the antenna and configured to generate a digital input signal from the electrical signal generated by the antenna, and

a bit extractor connected to the analog-to-digital converter and configured to extract the data bits from the digital input signal generated by the analog-to-digital converter,

wherein the bit extractor comprises a high pass filter configured to remove a DC-component from the digital signal by subtracting a moving minimum value of the digital input signal from a moving maximum value of the digital signal.

12. An RFID receiver, comprising:

an antenna configured to receive a radio signal from an RFID transmitter, and to generate an electrical signal from the radio signal received from the RFID transmitter; and

a decoder circuit connected to the antenna and configured to extract from the electrical signal generated by the antenna data bits encoded in the electrical signal; wherein the decoder circuit comprises:

an analog-to-digital converter connected directly to the antenna and configured to generate a digital input signal from the electrical signal generated by the antenna, and

a bit extractor connected to the analog-to-digital converter and configured to extract the data bits from the digital input signal generated by the analog-to-digital converter,

wherein the bit extractor is configured to determine varying sampling points using the moving decision threshold, and to sample the sub-bit pulses using the varying sampling points.

13. A method of extracting data bits encoded in a radio signal received from an RFID transmitter, the method comprising:

generating in an antenna of an RFID receiver an electrical signal from the radio signal received from the RFID transmitter;

connecting directly to the antenna an analog-to-digital converter;

generating in the analog-to-digital converter a digital input signal from the electrical signal generated by the antenna;

connecting a bit extractor to the analog-to-digital converter; and

extracting by the bit extractor the data bits from the digital input signal generated by the analog-to-digital converter;

wherein extracting by the bit extractor the data bits from the digital input signal comprises removing with a high pass filter of the bit extractor a DC-component from the digital signal by subtracting a moving minimum value of the digital input signal from a moving maximum value of the digital signal.

14. A method of extracting data bits encoded in a radio signal received from an RFID transmitter, the method comprising:

generating in an antenna of an RFID receiver an electrical signal from the radio signal received from the RFID transmitter;

connecting directly to the antenna an analog-to-digital converter;

generating in the analog-to-digital converter a digital input signal from the electrical signal generated by the antenna;

connecting a bit extractor to the analog-to-digital converter; and

extracting by the bit extractor the data bits from the digital input signal generated by the analog-to-digital converter;

wherein extracting by the bit extractor the data bits from the digital input signal comprises determining by the bit extractor varying sampling points using the moving decision threshold, and sampling the sub-bit pulses using the varying sampling points.