Method and Apparatus for Monitoring the Maximum Distance Between Two Objects

• US 20100219967A1
• Filed: 04/24/2007
• Published: 09/02/2010
• Est. Priority Date: 04/25/2006
• Status: Active Grant

• Current Assignee: Mission Control Design GmbH
• Original Assignee: Mission Control Design GmbH
• Inventors: Kaufmann, Hannes
• Granted Patent: US 8,063,789 B2
• Time in Patent Office: Days
• US Class Current: 340/686.600
• CPC Class Codes: G08B 21/0222 Message structure or message content, e.g. message protocol
• 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 21/025 System arrangements wherein the alarm criteria uses absence of reply signal after an elapsed time
• CPC Class Codes: H04B 17/23 Indication means, e.g. displays, alarms, audible means
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04W 52/228 using past power values or information
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile

Abstract

A method and an apparatus for monitoring the maximum distance between two objects, in particular between a child and its guardian, with the aid of two transceivers, the first of which periodically transmits status messages of a particular transmission power to the second, wherein an alarm is triggered in the second transceiver if the reception of the status messages decrease, and wherein a statement of the transmission power is concomitantly transmitted in each status message, are distinguished by the fact that the transmission power to be used for the next status message is determined by comparing the reception power with the transmission power stated in a status message and is transmitted back to the first transceiver in a confirmation message.

Claims

1. Method for monitoring the maximum distance between two objects (1, 2), in particular, of a child from its guardian, with the help of two transceivers (3, 4) of which the first periodically transmits status messages (ID_C, ST_C,i, TP_C,i) of a defined transmission power (TP_C,i) to the second, wherein an alarm is triggered in the second transceiver (4) when the reception of the status messages diminishes, and wherein data on the transmission power (TP_C,i) is also transmitted in each status message (ID_C, ST_C,i, TP_C,i), characterized in that, by comparing the reception power (RP_C,i) with the transmission power (TP_C,i) specified in a status message, the transmission power (TP_C,i+1) to be used for the next status message is determined and transmitted back to the first transceiver (3) in a confirmation message (ID_P, ST_P,i, TP_C,i+1).

2. Method according to claim 1 characterized in that the transmission power (TP_C,i+1) determined for the next status message (ID_C, ST_C,i−

1, TP_C,i+1) is also used for the transmission of the confirmation message (ID_P, ST_P,i, TP_C,i+1).

3. Method according to claim 1 or 2 characterized in that, in the mentioned comparison, a difference (TP_C,i−

RP_C,i) is formed from the specified transmission power and the measured reception power and is compared with a threshold (Δ

D_max), and when the difference falls below the threshold, the transmission power (TP_C,i+1) to be used for the next status message (ID_C, ST_C,i+1, TP_C,i+1) is reduced to a minimum value (min), while if the difference exceeds the threshold, it is increased to a maximum value (max), wherein, in the latter case, if the specified transmission power (TP_C,i+1) already has the maximum value (max), the alarm is triggered.

4. Method according to one of claims 1 to 3 characterized in that, in the pauses (S) of their periodic message exchange (M), the transceivers (3, 4) move into an energy-saving sleep mode, from which the second transceiver (4) awakes before the first transceiver (3).

5. Method according to one of claims 1 to 4 characterized in that the status message (ID_C, ST_C,i, TP_C,i) and the confirmation message (ID_P, ST_P,i, TP_C,i+1) each contain at least one unique identifier (ID_P, ID_C) that is assigned in an initialization step of two mutually associated transceivers (3, 4), whereupon each transceiver (3, 4) processes only status and confirmation messages of the other associated transceiver (4, 3).

6. Device for monitoring the maximum distance between two objects (1, 2), in particular, of a child from its guardian, with two transceivers (3, 4) of which the first periodically transmits status messages (ID_C, ST_C,i, TP_C,i) of a defined transmission power (TP_C,i) to the second, wherein the second transceiver (4) outputs an alarm when the reception of the status messages decreases, and wherein the first transceiver (3) also transmits data on the transmission power (TP_C,i) that is used in each status message (ID_C, ST_C,i, TP_C,i), characterized in that the second transceiver (4) is constructed to determine the transmission power (TP_C,i+1) to be used for the next status message from a comparison of the reception power (RP_C,i) with the transmission power specified in a status message, and transmits it back to the first transceiver (3) in a confirmation message (ID_P, ST_P,i, TP_C,i+1).

7. Device according to claim 6 characterized in that the second transceiver (4) is constructed to transmit the confirmation message (ID_p, ST_P,i, TP_C,i+1) with the transmission power (TP_C,i+1) determined for the next status message (ID_C, ST_C,i+1, TP_C,i+1).

8. Device according to claim 6 or 7 characterized in that the second transceiver (4) is constructed to form the difference (TP_C,i−

RP_C,i) from the specified transmission power and the measured reception power for each status message (ID_C, ST_C,i, TP_C,i) and to compare it with a threshold (Δ

D_max ), and if the difference falls below the threshold, the transmission power (TP_C,i+1) to be used for the next status message (ID_C, ST_C,i+1, TP_C,i+1) is reduced to a min value (min), while if the difference exceeds the threshold, it is increased to a maximum value (max), and, in the latter case, to output the alarm if the specified transmission power (TP_C,i) already has the maximum value (max).

9. Device according to one of claims 6 to 8 characterized in that the second transceiver (4) has a display device (15) for the mentioned difference (TP_C,i−

RP_C,i) of the specified transmission power and the measured reception power.

10. Device according to one of claims 6 to 9 characterized in that the first and/or the second transceiver (3;

4) is each equipped with an emergency call button (12) that transmits an emergency call message to the other transceiver (4;

3).

11. Device according to one of claims 6 to 10 characterized in that the second transceiver (4), and preferably also the first transceiver (3), each have an acoustic alarm device (16) and preferably also a vibrational alarm device (17).

12. Device according to one of claims 6 to 11 characterized in that the transceivers (3, 4) are constructed in the form of armbands.