Radio receiver for use in a radio tracking system

• US 5,722,064 A
• Filed: 12/06/1995
• Issued: 02/24/1998
• Est. Priority Date: 02/24/1995
• Status: Expired due to Term

• Current Assignee: NTP Incorporated
• Original Assignee: NTP Incorporated
• Inventors: Campana, Thomas J. Jr.
• Primary Examiner(s): MULLEN, THOMAS J
• Application Number:
  US08/568,434
• Time in Patent Office: 811 Days
• Field of Search: 455/347, 455/351, 455/226.2, 455/226.4, 340/573, 340/693, 340/825.49, 340/691, 343/702, 342/176, 342/419, 342/443, 345/905, 359/609, 367/108
• US Class Current: 455/351
• CPC Class Codes: G08B 21/0222 Message structure or message content, e.g. message protocol
• CPC Class Codes: G08B 21/0227 System arrangements with a plurality of child units
• CPC Class Codes: G08B 21/023 Power management, e.g. system sleep and wake up provisions
• CPC Class Codes: G08B 21/0247 System arrangements wherein the alarm criteria uses signal strength
• CPC Class Codes: G08B 21/0263 System arrangements wherein the object is to detect the direction in which child or item is located
• CPC Class Codes: H04B 17/18 Monitoring during normal operation
• CPC Class Codes: H04B 17/23 Indication means, e.g. displays, alarms, audible means
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0072 Error control for data other than payload data, e.g. control data
• CPC Class Codes: H04L 1/20 using signal quality detector

Abstract

A radio receiver unit for directionally tracking at least one radio transmitter in accordance with the invention includes a housing containing a radio receiver including a directional antenna for receiving radio transmissions from the at least one radio transmitter; a display, which is electrically coupled to the receiver and fixed in position with respect to the housing, for visually displaying a strength of the radio transmissions received by the directional antenna; and a field of view limiter for limiting light emanating from the display to a field of view of the display when a user holds the receiver unit in the user'"'"'s hand away from the body of the user, the field of view being limited to planes extending upward from a plane of sight extending from the eyes of the user downward and intersecting a horizontal plane extending from the user'"'"'s waist substantially at arms length of the user.

Claims

1. A radio receiver unit for directionally tracking at least one radio transmitter comprising:

a housing containing a radio receiver including a directional antenna for receiving radio transmissions from the at least one radio transmitter;

a display, which is electrically coupled to the receiver and fixed in position with respect to the housing, for visually displaying a strength of the radio transmissions received by the directional antenna; and

a field of view limiter for limiting light emanating from the display to a field of view of the display when a user holds the receiver unit in the user'"'"'s hand away from the body of the user, the field of view being limited to planes extending upward from a plane of sight extending from the eyes of the user downward and intersecting a horizontal plane extending from the user'"'"'s waist substantially at arms length of the user.

2. A radio receiver unit in accordance with claim 1 wherein:

the field of view limiter limits the field of view of the display by the user to planes extending upward from a plane of sight extending from the eyes of the user downward and intersecting a horizontal plane extending from the user'"'"'s chest substantially at arms length of the user.

3. A radio receiver unit in accordance with claim 2 wherein:

the field of view limiter is contained within the housing.

4. A radio receiver unit in accordance with claim 3 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

5. A receiver unit in accordance with claim 4 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

6. A radio receiver unit in accordance with claim 3 wherein the field of view limiter comprises:

an opening within the housing extending inward from an outer surface of the housing and having a bottom with the display being positioned at the bottom.

7. A radio receiver unit in accordance with claim 6 wherein:

the field of view limited by the field of view limiter is defined by a pair of straight lines respectively extending from opposed edges of the display to opposed edges of the opening.

8. A radio receiver unit in accordance with claim 7 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

9. A receiver unit in accordance with claim 8 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

10. A radio receiver unit in accordance with claim 6 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

11. A receiver unit in accordance with claim 10 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

12. A radio receiver unit in accordance with claim 2 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

13. A receiver unit in accordance with claim 12 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

14. A radio receiver unit in accordance with claim 1 wherein:

the field of view limiter is contained within the housing.

15. A radio receiver unit in accordance with claim 14 wherein the field of view limiter comprises:

an opening within the housing extending inward from an outer surface of the housing and having a bottom with the display being positioned at the bottom.

16. A radio receiver unit in accordance with claim 15 wherein:

the field of view limited by the field of view limiter is defined by a pair of straight lines respectively extending from opposed edges of the display to opposed edges of the opening.

17. A radio receiver unit in accordance with claim 16 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

18. A radio receiver unit in accordance with claim 15 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

19. A receiver unit in accordance with claim 18 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

20. A radio receiver unit in accordance with claim 14 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

21. A receiver unit in accordance with claim 20 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

22. A radio receiver unit in accordance with claim 1 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

23. A receiver unit in accordance with claim 22 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

24. A radio receiver unit for directionally tracking at least one radio transmitter comprising:

a housing containing a radio receiver including a directional antenna for receiving radio transmissions from the at least one radio transmitter;

a display, which is electrically coupled to the receiver and fixed in position with respect to the housing, for visually displaying a strength of the radio transmissions received by the directional antenna from the at least one radio transmitter; and

a field of view limiter for limiting light emanating from the display to a field of view of the display wherein in order to view the display a user holds the receiver unit in the user'"'"'s hand away from the body of the user and at least at waist height and above, the field of view subtending an angle not greater than 45°

, the angle being defined by a pair of lines respectively extending between opposed edges of the display and edges of the field of view limiter.

25. A radio receiver unit in accordance with claim 24 wherein:

the angle is not greater than 30°

.

26. A radio receiver unit in accordance with claim 25 wherein:

the field of view limiter is contained within the housing.

27. A radio receiver unit in accordance with claim 26 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

28. A receiver unit in accordance with claim 27 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

29. A radio receiver unit in accordance with claim 26 wherein the field of view limiter comprises:

an opening within the housing extending inward from an outer surface of the housing and having a bottom with the display being on the bottom.

30. A radio receiver unit in accordance with claim 29 wherein:

the field of view limited by the field of view limiter is defined by a pair of straight lines respectively extending from opposed edges of the display to opposed edges of the opening.

31. A radio receiver unit in accordance with claim 30 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

32. A receiver unit in accordance with claim 31 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

33. A radio receiver unit in accordance with claim 29 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

34. A receiver unit in accordance with claim 33 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

35. A radio receiver unit in accordance with claim 25 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

36. A receiver unit in accordance with claim 35 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

37. A radio receiver unit in accordance with claim 24 wherein:

the field of view limiter is contained within the housing.

38. A radio receiver unit in accordance with claim 37 wherein the field of view limiter comprises:

an opening within the housing extending inward from an outer surface of the housing and having a bottom with the display being positioned at the bottom.

39. A radio receiver unit in accordance with claim 38 wherein:

the field of view limited by the field of view limiter is defined by a pair of straight lines respectively extending from opposed edges of the display to opposed edges of the opening.

40. A radio receiver unit in accordance with claim 39 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

41. A receiver unit in accordance with claim 40 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

42. A radio receiver unit in accordance with claim 38 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

43. A receiver unit in accordance with claim 42 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

44. A radio receiver unit in accordance with claim 37 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

45. A receiver unit in accordance with claim 44 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.

46. A radio receiver unit in accordance with claim 24 further comprising:

a switch, coupled to the receiver, the switch having a first position at which the directional antenna is not operative to receive the radio transmissions from the at least one radio transmitter and a second position at which the directional antenna is operative to receive the radio transmissions from the at least one radio transmitter, the switch being positioned relative to the housing so that a hand of the user of the receiver during directional tracking of the at least one transmitter holds the switch in the second position; and

wherein

the directional antenna is positioned relative to the housing so that during the holding of the switch in the second position by the user'"'"'s hand a line of sight between the directional antenna and the at least one radio transmitter is not occluded by the user'"'"'s hand holding the switch in the second position.

47. A receiver unit in accordance with claim 46 wherein:

the field of view limiter is set in the housing in front of the directional antenna with reference to a line of sight extending between the user and the at least one transmitter.