RF door activation system

• US 20050190798A1
• Filed: 02/04/2005
• Published: 09/01/2005
• Est. Priority Date: 11/17/1999
• Status: Active Grant

• Current Assignee: MS Sedco, Inc.
• Original Assignee: MS SEDCO
• Inventors: Benson, Raymond G. Jr., Chau, Phong B.
• Granted Patent: US 7,545,833 B2
• Time in Patent Office: Days
• US Class Current: 370/516
• CPC Class Codes: G07C 2009/00793 by Hertzian waves
• CPC Class Codes: G07C 2009/00928 for garage doors
• CPC Class Codes: G07C 2209/08 With time considerations, e.g. temporary activation, valid time window or time limitations
• CPC Class Codes: G07C 9/00182 operated with unidirectional data transmission between data carrier and locks
• CPC Class Codes: H04L 7/0004 Initialisation of the receiver H04L7/0075 and H04L7/10 take precedence
• CPC Class Codes: H04L 7/0012 by comparing receiver clock with transmitter clock
• CPC Class Codes: H04L 7/041 using special codes as synchronising signal
• CPC Class Codes: H04L 7/10 Arrangements for initial synchronisation

Abstract

The present invention provides a radio frequency (“RF”) activation system with improved operating capability and ease of installation. Improved responsiveness is provided by the receiver which determines the frame timing of incoming signals and calculates the estimated time of arrival for ensuing frames thus minimizing loss of frame synchronization problems. In one embodiment, this is accomplished by determining the time span of the frame start sequence and using this to determine the frame timing of an incoming RF signal. The receiver also makes corrections for timing errors between the receiver and transmitter by re-synchronizing the receiver with the incoming RF signal.

Claims

1. A receiver for a door activation system, the receiver having frame timing, the receiver comprising:

means for receiving an incoming RF signal;

means for determining frame timing of the incoming signal; and

means for adjusting the frame timing of the receiver to be closer to the frame timing of the incoming signal.

2. The receiver of claim 1, wherein the incoming signal comprises at least a first and a second frame and wherein the means for determining frame timing of the incoming further comprises:

means for determining the time difference between the receipt of the first frame and the second frame of the incoming signal;

means for determining frame timing of the incoming signal based on the time difference;

means for determining if the time difference is valid for use in determining frame timing; and

means for rejecting non-valid time differences, such that receiver frame timing is not adjusted based on invalid time differences.

3. The receiver of claim 2, wherein the first frame and the second frame comprise a first frame start bit and a second frame start bit respectively, the first and second frame start bits each having a falling edge, and wherein the means for determining time difference between the receipt of the first frame and the second frame comprises:

means for detecting the falling edges of the first and second frame start bits, such that the time difference is determined by the time difference between detection of the falling edge of the first frame and detection of the falling edge of the second frame.

4. The receiver of claim 1, wherein the incoming signal comprises a frame start bit sequence of at least two bits, the frame start bit sequence having a rising edge of a bit and a falling edge of a bit, and wherein the means for determining frame timing comprises:

means for detecting the rising edge of the frame start bit sequence;

means for detecting the falling edge of the frame start bit sequence; and

means for determining the time difference between the rising edge and the falling edge, such that the frame timing of the receiver is adjusted based on the determined time difference.

5. The receiver of claim 4, further comprising:

means for determining if the time difference is valid for use in determining frame timing; and

means for rejecting non-valid time differences, such that receiver frame timing is not adjusted based on invalid time differences.

6. A receiver for a door activation system, the receiver having bit timing, the receiver further comprising:

means for receiving an incoming RF signal, the incoming signal having bit timing; and

means for reducing bit timing errors, such that bit timing errors between the bit timing of the receiver and the bit timing of the incoming signal are reduced.

7. The receiver of claim 6, wherein the incoming signal comprises a first frame, the first frame having a first and a second data bit, and wherein the means for reducing bit timing errors further comprises:

means for assigning a frame timing to be associated with the incoming signal;

means for estimating the time of arrival of the data bits within a frame, the time of arrival being based upon the frame timing;

means for monitoring a frame of the incoming signal for data bits;

means for determining that the first data bit has been received; and

means for adjusting the estimated time of arrival for the second data bit based upon the receipt of the first data bit.

8. The receiver of claim 7, wherein the first frame comprises a first frame start bit sequence of at least one bit, the first frame start bit sequence having a falling edge, the signal further comprising a second frame having a second frame start bit sequence of at least one bit, the second frame start bit sequence having a falling edge, and wherein the means for assigning a frame timing to be associated with an incoming signal comprises:

means for detecting the falling edges of the first and second frame start bit sequences;

means for associating time with the falling edges;

means for determining the time difference between the falling edges; and

means for determining the frame timing of the incoming signal based on the time difference.

9. The receiver of claim 8, the means for assigning a frame timing to be associated with an incoming signal further comprising:

means for determining if the time difference is valid for use in determining frame timing; and

means for rejecting non-valid time differences, such that receiver frame timing is not adjusted based on invalid time differences.

10. The receiver of claim 9, wherein the means for determining if the time difference is valid comprises:

means for comparing the time difference with a range of acceptable time differences; and

means for rejecting time differences which exceed the range of acceptable time differences.

11. The receiver of claim 7, wherein the incoming signal comprises a frame start bit sequence of at least one bit, the frame start sequence having a rising edge and a falling edge, and wherein the means for assigning a frame timing to be associated with an incoming signal comprises:

means for detecting the rising edge;

means for detecting the falling edge;

means for determining the time difference between the rising edge and the falling edge; and

means for determining the frame timing of the incoming signal based on the time difference.

12. The receiver of claim 11, wherein the means for assigning a frame timing to be associated with a received signal further comprises:

means for determining if the time difference is valid for use in determining frame timing; and

means for rejecting non-valid time differences, such that receiver frame timing is not adjusted based on invalid time differences.

13. The receiver of claim 12, wherein the means for determining if the time difference is valid comprises:

means for comparing the time difference with a range of acceptable time differences; and

means for rejecting time differences which exceed the range of acceptable time differences.

14. A method of frame timing calibration in a door activation system comprising the steps of:

providing an RF receiver, the receiver having frame timing;

receiving an incoming RF signal with the receiver;

determining the frame timing of the incoming signal; and

adjusting the receiver frame timing based on the frame timing of the incoming signal.

15. The method of claim 14, wherein the incoming signal comprises a frame start sequence of at least one bit having a first rising edge, and a last falling edge and wherein the step of determining the frame timing of the incoming signal comprises the steps of:

detecting the first rising edge;

detecting the last falling edge; and

determining the time difference between the first rising edge and the last falling edge.

16. The method of claim 15, further comprising, after the step of determining the time difference, the steps of:

determining if the time difference is valid for use in determining frame timing; and

rejecting non-valid time differences, such that receiver frame timing is not adjusted based on invalid time differences.

17. The method of claim 14, wherein the incoming signal comprises a first and a second frame, and wherein the step of determining frame timing comprises the steps of:

detecting the first frame of the incoming signal;

detecting the second frame of the incoming signal; and

determining the time difference between the time of detection of the first frame and the time of detection of the second frame.

18. The method of claim 17, wherein the first and second frame of the incoming signal comprise a first and a second falling edge, respectively, and wherein the step of detecting the first frame comprises the step of:

detecting the first falling edge; and

wherein the step of detecting the second frame comprises the step of;

detecting the second falling edge.

19. The method of claim 17, further comprising, after the step of determining the time difference, the steps of:

determining if the time difference is valid for use in determining frame timing; and

rejecting non-valid time differences, such that receiver frame timing is not adjusted based on invalid time differences.

20. The method of claim 19, wherein the step of determining if the time difference is a valid frame timing comprises the steps of:

providing a reference time difference; and

comparing the determined time difference to the reference.

21. A method for reducing timing errors in a door activation system comprising the steps of:

providing an RF receiver;

receiving an incoming RF signal, the incoming RF signal having bit timing and comprising a first data bit and an ensuing data bit;

determining the bit timing to be associated with the incoming RF signal;

using the determined bit timing to estimate the time of arrival of a first data bit within the incoming RF signal;

monitoring the incoming RF signal for a first data bit;

determining a time that the first data bit has been received; and

using the determined bit timing and the determined time that the first data bit was received to estimate the time of arrival of the ensuing data bit within the incoming RF signal.

22. The method of claim 21, wherein the step of using the determined bit timing to estimate the time of arrival of data bits within the incoming RF signal further comprises the steps of:

providing a counter;

setting the counter to a nominal setting; and

using the counter to count until the first data bit should have arrived, and wherein the step of using the determined bit timing and the determined time that the first data bit was received to estimate the time of arrival of the ensuing data bit within the incoming RF signal comprises the step of resetting the counter to the nominal setting and counting until the ensuing data bit should have arrived.

23. The method of claim 22, wherein the step of determining that a data bit has been received comprises the step of:

determining whether a one to zero data transition has occurred or if the counter has counted the time until the first data bit should have arrived.