Granted Patent B2

US 8,598,988 · App. 12/732,797 · Granted Dec 3, 2013

Abstract

Claims (70)

1. A system for monitoring a plurality of RFID tags, the system comprising:

a plurality of serially connected receivers along a receive path, a serially connected receiver configured to:

relay a received receiver selection signal when a receiver selection signal identifies a selected receiver as being further along the receive path than the serially connected receiver;

listen for an RFID response signal when the receiver selection signal identifies the serially connected receiver as being the selected receiver; and

operate in a standby mode when the receiver selection signal identifies the selected receiver as being closer on the receive path than the serially connected receiver;

a plurality of serially connected transmitters along a transmit path, a serially connected transmitter configured to:

relay a received transmitter selection signal when a transmitter selection signal identifies a selected transmitter as being further along the transmit path than the serially connected transmitter;

transmit an identification impulse when the transmitter selection signal identifies the serially connected transmitter as being the selected transmitter; and

operate in a standby mode when the transmitter selection signal identifies the selected transmitter as being closer on the transmit path than the serially connected transmitter; and

a reader responsive to a plurality of receive paths that include a plurality of serially connected receivers on a receive path, the reader being further responsive to a plurality of transmit paths that include a plurality of serially connected transmitters on a transmit path, the reader being configured to send the receiver selection signal along a selected receive path, the receiver selection signal identifying one of the plurality of serially connected receivers along the selected receive path as the selected receiver for listening for an RFID response signal, the reader being further configured to send the transmitter selection signal along a selected transmit path, the transmitter selection signal identifying one of the plurality of serially connected transmitters along the selected transmit path as the selected transmitter for transmitting the identification impulse;

wherein the plurality of RFID tags include a plurality of first-protocol RFID tags and a plurality of second-protocol RFID tags, a first-protocol using passive RFID tags, a second-protocol using battery assisted RFID tags;

wherein the transmitter selection signal further identifies a selected protocol according to which of the first-protocol and the second-protocol the identification impulse is to be transmitted;

wherein the selected transmitter transmits the identification impulse in a low-power mode if the selected protocol is the second-protocol; and

wherein the selected transmitter transmits the identification impulse in a high-power mode if the selected protocol is the first-protocol.

2. The system of claim 1 , wherein the receiver selection signal comprises:

a start indicator; and

a receiver selection indicator;

wherein a length of a receiver selection time period between the start indicator and the receiver selection indicator identifies the selected receiver.

3. The system of claim 2 , wherein a second receiver along the selected receive path is the selected receiver when the receiver selection time period is two units in length;

wherein a third receiver along the selected receive path is the selected receiver when the receiver selection time period is three units in length.

4. The system of claim 1 , wherein the reader identifies a selected receiver by a voltage of the receiver selection signal sent along the receive path.

5. The system of claim 1 , wherein a serially connected receiver comprises:

an antenna path; and

a hardwired input path;

wherein the antenna path is utilized when the serially connected receiver is the selected receiver.

6. The system of claim 1 , wherein a position of a serially connected receiver in a receive path is identified via a manually adjusted mechanism on the serially connected receiver.

7. A system for monitoring a plurality of RFID tags, the system comprising:

a plurality of serially connected receivers along a receive path, a serially connected receiver configured to:

relay a received receiver selection signal when a receiver selection signal identifies a selected receiver as being further along the receive path than the serially connected receiver;

listen for an RFID response signal when the receiver selection signal identifies the serially connected receiver as being the selected receiver; and

operate in a standby mode when the receiver selection signal identifies the selected receiver as being closer on the receive path than the serially connected receiver;

wherein a serially connected receiver comprises an amplifier;

wherein the serially connected receiver relays a received receiver selection signal using a first gain;

wherein the serially connected receiver relays a calibration signal at a second gain;

wherein the second gain is less than the first gain; and

wherein the serially connected receiver identifies a position in the receive path based on in which of a plurality of ranges the calibration signal is measured at the serially connected receiver; and

a reader responsive to a plurality of receive paths that include a plurality of serially connected receivers on a receive path, the reader being configured to send the receiver selection signal along a selected receive path, the receiver selection signal identifying one of the plurality of serially connected receivers along the selected receive path as the selected receiver for listening for an RFID response signal.

8. A system for monitoring a plurality of RFID tags, the system comprising:

a plurality of serially connected transmitters along a transmit path, a serially connected transmitter configured to:

relay a received transmitter selection signal when a transmitter selection signal identifies a selected transmitter as being further along the transmit path than the serially connected transmitter;

transmit an identification impulse when the transmitter selection signal identifies the serially connected transmitter as being the selected transmitter; and

operate in a standby mode when the transmitter selection signal identifies the selected transmitter as being closer on the transmit path than the serially connected transmitter; and

a reader responsive to a plurality of transmit paths that include a plurality of serially connected transmitters on a transmit path, the reader being configured to send the transmitter selection signal along a selected transmit path, the transmitter selection signal identifying one of the plurality of serially connected transmitters along the selected transmit path as the selected transmitter for transmitting the identification impulse;

wherein the plurality of RFID tags include a plurality of first-protocol RFID tags and a plurality of second-protocol RFID tags, a first-protocol using passive RFID tags, a second-protocol using battery assisted RFID tags;

wherein the transmitter selection signal further identifies a selected protocol according to which of the first-protocol and the second-protocol the identification impulse is to be transmitted;

wherein the selected transmitter transmits the identification impulse in a low-power mode if the selected protocol is the second-protocol; and

wherein the selected transmitter transmits the identification impulse in a high-power mode if the selected protocol is the first-protocol.

9. The system of claim 8 , wherein the transmitter selection signal comprises:

a start indicator; and

a transmitter selection indicator;

wherein a length of a transmitter selection time period between the start indicator and the transmitter selection indicator identifies the selected transmitter.

10. The system of claim 8 , wherein the reader identifies a selected transmitter by a voltage of the transmitter selection signal sent along the transmit path.

11. The system of claim 8 , wherein a serially connected transmitter comprises:

an antenna path; and

a hardwired output path;

wherein the antenna path is utilized when the serially connected transmitter is the selected transmitter.

12. The system of claim 8 , wherein a position of a serially connected transmitter in a transmit path is identified via a manually adjusted mechanism on the serially connected transmitter.

13. The system of claim 8 , wherein a position of a serially connected transmitter in a transmit path is identified by measuring a signal strength of a calibration signal at the serially connected transmitter.

14. A system for monitoring a plurality of RFID tags, the system comprising:

a plurality of serially connected transmitters along a transmit path, a serially connected transmitter configured to:

relay a received transmitter selection signal when a transmitter selection signal identifies a selected transmitter as being further along the transmit path than the serially connected transmitter;

transmit an identification impulse when the transmitter selection signal identifies the serially connected transmitter as being the selected transmitter; and

operate in a standby mode when the transmitter selection signal identifies the selected transmitter as being closer on the transmit path than the serially connected transmitter; and

a reader responsive to a plurality of transmit paths that include a plurality of serially connected transmitters on a transmit path, the reader being configured to send the transmitter selection signal along a selected transmit path, the transmitter selection signal identifying one of the plurality of serially connected transmitters along the selected transmit path as the selected transmitter for transmitting the identification impulse;

wherein a serially connected transmitter comprises an amplifier;

wherein the serially connected transmitter relays a received transmitter selection signal using a first gain;

wherein the serially connected transmitter relays a calibration signal at a second gain;

wherein the second gain is less than the first gain;

wherein the serially connected transmitter identifies a position in the transmit path based on which of a plurality of ranges the calibration signal is measured at the serially connected transmitter.

15. The system of claim 14 , wherein a transmitter utilizes two linear crossed dipole antennas radiating sequentially in transmitting the identification impulse.

Assignments (11)