Proximity alert system

• US 5,298,883 A
• Filed: 01/17/1992
• Issued: 03/29/1994
• Est. Priority Date: 01/17/1992
• Status: Expired due to Fees

• Current Assignee: Ham, Ronald E., Richard G. Pilney
• Original Assignee: Ham, Ronald E., Richard G. Pilney
• Inventors: Ham, Ronald E., Pilney, Richard G.
• Primary Examiner(s): Peng, John K.
• Assistant Examiner(s): MULLEN, THOMAS J
• Application Number:
  US07/822,120
• Time in Patent Office: 802 Days
• Field of Search: 340/573, 340/691, 340/384 E, 340/574, 340/329, 340/331, 340/311.1, 340/435-436, 340/903, 340/825.49, 340/825.44, 340/825.19, 455/88-89, 343/702, 342/24, 342/118, 342/132, 364/561
• US Class Current: 340/573.2
• CPC Class Codes: G01S 13/825 with exchange of information between interrogator and responder
• CPC Class Codes: G01S 3/24 the separate antennas comprising one directional antenna and one non-directional antenna, e.g. combination of loop and open antennas producing a reversed cardioid directivity characteristic
• 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: G08B 21/22 responsive to presence or absence of persons
• CPC Class Codes: H04B 1/38 Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving

Abstract

A proximity alert system including a pair of portable electronic, coded transmitter/receiver units designed to operate in a specific signal band. Each unit transmits a coded signal that is picked up by the other unit. The strength of the received coded signal controls the rate of an audible beeper. The rate of the beeper indicates the approximate distance between companion units. A direction-finder antenna is used to indicate the direction of the received coded signal.

Claims

1. A portable proximity alert system, comprising:

a first portable unit including transmitter means for producing a first coded signal, receiver means for receiving and determining the strength of a second coded signal, and first warning means for producing a variable rate proximity warning signal having a frequency variable in proportion to the strength of the second coded signal received by the first portable unit;

a second portable unit including transmitter means for producing the second coded signal, receiver means for receiving and determining the strength of the first coded signal, and second warning means for producing a variable rate proximity warning signal having a frequency variable in proportion to the strength of the first coded signal received by the second portable unit;

wherein each receiver means determines which of a plurality of distance ranges corresponds to the distance between the first and second portable units based on the strength of the corresponding received coded signal; and

wherein the variable rate proximity warning signal produced by each warning means takes on a particular frequency corresponding to the particular distance range determined by the corresponding receiver means to correspond to the distance between the first and second portable units.

2. The alert system of claim 1 wherein the first warning means produces an audible warning signal.

3. The alert system of claim 2 wherein the audible warning signal is a discrete sound repeated at an increasing rate as the first and second units approach each other, whereby the approximate distance between the first and second units can be determined.

4. The alert system of claim 1 wherein the second warning means produces an audible warning signal.

5. The alert system of claim 3 wherein the audible warning signal is a discrete sound repeated at an increasing rate as the first and second units approach each other, whereby the approximate distance between the first and second units can be determined.

6. The alert system of claim 1 wherein the first portable unit further includes means for finding the direction of the second coded signal received from the second portable unit.

7. The alert system of claim 1 wherein the second portable unit further includes means for finding the direction of the first coded signal received from the first portable unit.

8. The alert system of claim 1 wherein the first portable unit further includes means for producing a first coded emergency signal.

9. The alert system of claim 1 wherein the second portable unit further includes means for producing a second coded emergency signal.

10. The alert system of claim 1 wherein the first portable unit further includes a battery power source having means for indicating low battery voltage.

11. The alert system of claim 1 wherein the second portable unit further includes a battery power source having means for indicating low battery voltage.