METHOD FOR SYNCHRONIZING FREQUENCY-HOPPING SHORT-RANGE RADIO DEVICES

• US 20090167521A1
• Filed: 12/31/2007
• Published: 07/02/2009
• Est. Priority Date: 12/31/2007
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: White, Theodore A., Edwards, Lewin A., Albrechtsen, Stanley W.
• Granted Patent: US 7,961,091 B2
• Time in Patent Office: Days
• US Class Current: 340/539.100
• CPC Class Codes: H04B 1/7143 Arrangements for generation of hop patterns
• CPC Class Codes: H04B 1/7156 Arrangements for sequence synchronisation

Abstract

A method for synchronizing a security system control panel and a sensor. The control panel and the sensor each have a transceiver. The control panel monitors a publicly broadcast signal for an time signal, periodically receives the time signal, calculates a frequency hopping index pointer using the time signal and accesses a frequency hopping table using the frequency hopping index pointer. The frequency hopping table is used by the control panel to determine when to hop between multiple receiving channels and which of the receiving channels to hop. The sensor wakes up from a standby mode when the sensor determines that the sensor is to send data, receives the publicly broadcast signal that includes a time signal, selects the channel that the control panel is actively receiving data using the time signal and transmits the data to the control panel using the selected channel.

Claims

1. A method for synchronizing a security system control panel and a sensor, where the security system control panel and the sensor each have a transceiver, the method comprising the steps of:

monitoring a publicly broadcast signal for a time signal by the security system control panel;

receiving periodically the time signal at the security system control panel;

calculating a frequency hopping index pointer by the security system control panel using the time signal; and

accessing a frequency hopping table using the frequency hopping index pointer, the frequency hopping table is used by the security system control panel to determine when to hop between a plurality of different receiving channels and which of the plurality of different receiving channels to hop.

2. The method for synchronizing a security system control panel and a sensor according to claim 1, further comprising the steps of:

waking up from a standby mode when a sensor determines that the sensor is to send data;

receiving the publicly broadcast signal that includes a time signal by the sensor;

selecting using the time signal which of the plurality of different receiving channels that the security system control panel is actively receiving data; and

transmitting the data to the security system control panel using the selected channel.

3. The method for synchronizing a security system control panel and a sensor according to claim 1, wherein said publicly broadcast signal is a GPS or other radionavigation signal.

4. The method for synchronizing a security system control panel and a sensor according to claim 1, wherein said publicly broadcast signal is a cellular telephone control signal comprising a broadcast timestamp.

5. The method for synchronizing a security system control panel and a sensor according to claim 2, further comprising the steps of:

determining if another sensor is transmitting or receiving data on the predicted channel; and

transmitting the data to the security system control panel when the result of the determining is that the selected channel does not have any data being actively transmitted.

6. The method for synchronizing a security system control panel and a sensor according to claim 1, where the calculating step comprises the substeps of:

extracting a preset number of least-significant bits from the time signal; and

generating the frequency hopping index pointer from the preset number of least-significant bits.

7. The method for synchronizing a security system control panel and a sensor according to claim 2, where the selecting step comprises the substeps of:

extracting a preset number of least-significant bits from the time signal; and

selecting one of the plurality of receiving channels for the security system control panel according to the preset number of least-significant bits.

8. The method for synchronizing a security system control panel and a sensor according to claim 1, where the calculating step comprises the substeps of:

hashing bits from the time signal to a predetermined bit stream; and

generating the frequency hopping index pointer from the predetermined bit stream.

9. The method for synchronizing a security system control panel and a sensor according to claim 2, where the selecting step comprises the substeps of:

hashing bits from the time signal to a predetermined bit stream; and

selecting one of the plurality of receiving channels for the security system control panel according to the predetermined bit stream.