Portable RFID reading terminal with visual indication of scan trace

1. A radio-frequency identifier (RFID) reader comprising:

a radio frequency (RF) antenna that outputs an RF signal;

wherein a scan trace is displayed in response to outputting the RF signal and the scan trace comprises a plurality of time-varying points, each point being defined by a projection of the RF signal transmitted by the RFID antenna onto a plane at a given moment in time.

2. The RFID reader of claim 1 , wherein, by reading RFID tags attached to items, an inventory of items stored in a facility are reconciled against at least one of: an expected inventory list and an expected count of items.

3. The RFID reader of claim 2 , wherein the RFID reader is configured to receive from an external computer at least one of: the expected inventory list and the expected count of items.

4. The RFID reader of claim 3 , further comprising a user interface;

wherein at least one of the expected inventory list and the expected count of items is received via the user interface.

5. The RFID reader of claim 3 , further comprising a two-dimensional imager;

wherein at least one of the expected inventory list and the expected count of items is received via the two-dimensional imager.

6. The RFID reader of claim 2 , wherein at least one of: (1) the expected inventory list and (2) the expected count of items, is received from an external memory device.

7. The RFID reader of claim 3 ,

wherein at least one of: a list of read RFID tags and a count of read RFID tags is transmitted to a second external computer.

8. The RFID reader of claim 1 , further comprising a display that displays the scan trace.

9. The RFID reader of claim 1 , further comprising a two-dimensional imager;

wherein each point is defined by a projection of a coverage shape of an RF signal transmitted by the RFID antenna onto the plane at a given moment in time, and

wherein a spatial position of the coverage shape of the RF signal is determined based on a known position and orientation of the RF antenna relatively to a position of a field of view of the two-dimensional imager.

10. The RFID reader of claim 1 , further comprising a two-dimensional imager;

wherein each point is defined by a projection of a coverage shape of an RF signal transmitted by the RFID antenna onto the plane at a given moment in time,

wherein a distance to an object is measured using the two-dimensional imager; and

wherein a projection of the RF signal coverage shape determined and displayed onto the plane defined by a physical structure.

11. The RFID reader of claim 1 , further comprising at least one accelerometer;

wherein each point is defined by a projection of a coverage shape of an RF signal transmitted by the RFID antenna onto the plane at a given moment in time, and

wherein a change of a spatial position and orientation of the RF signal coverage shape is determined based on proper acceleration values received from the at least one accelerometer.

12. The RFID reader of claim 1 , wherein at least one of the following is displayed:

a quantity of scanned items, a quantity of items which have not be scanned yet, and a total quantity of items to be scanned.

13. The RFID reader of claim 1 , wherein an indicator of a ratio of quantity of scanned items to a total quantity of items to be scanned is displayed.

14. The RFID reader of claim 1 , wherein the scan trace is displayed overlaid over an image of a physical structure.

15. The RFID reader of claim 14 , wherein the image of the physical structure is received.

16. The RFID reader of claim 1 , wherein a description of a physical structure is received;

wherein an image of the physical structure is created based on the description; and

wherein the scan trace is displayed overlaid over the image of the physical structure.

17. The RFID reader of claim 1 , further comprising a two-dimensional imager;

wherein, using the two-dimensional imager, an image of a physical structure is acquired; and

wherein the scan trace is displayed overlaid over the image of the physical structure.

18. The RFID reader of claim 1 , wherein an indicator of an RF signal coverage is displayed over the scan trace overlaid over an image of a physical structure.

19. The RFID reader of claim 1 , wherein an indicator of an RF signal coverage is displayed over a current position within the scan trace.

20. A method comprising:

outputting an RF signal from an radio-frequency identifier (RFID) reader;

displaying a scan trace in response to the outputting the RF signal, wherein the scan trace comprises a plurality of time-varying points that are each defined by a projection of the RF signal transmitted by the RFID antenna onto a plane at a given moment in time.