System and method for fast detection of specific on-air data rate

• US 20050057371A1
• Filed: 09/01/2004
• Published: 03/17/2005
• Est. Priority Date: 09/05/2003
• Status: Active Grant

• Current Assignee: Itron, Inc.
• Original Assignee: Itron, Inc.
• Inventors: Larson, Gary, Fitzgerald, Aaron, Stroda, Kris
• Granted Patent: US 7,412,235 B2
• Time in Patent Office: Days
• US Class Current: 340/870.20
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: H04Q 9/00 Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom

Abstract

A system and method for fast detection of specific on-air data rates are disclosed which, in one example embodiment, enable endpoint devices in automatic meter reading (AMR) systems to quickly determine the existence of over-the-air information that is specifically targeted to a unique class of AMR devices. An endpoint device utilizing the digital squelch circuit arrangement and algorithm of the invention can quickly and precisely determine if the AMR system is communicating with its class of AMR device by looking for a specific non-standard data rate present on the air. This method therefore allows for a significant improvement in battery life in two-way RF communication units by avoiding unnecessary data processing and data transmissions. The digital squelch method also enables even faster determination of inappropriate data rates and of no signal present situations, further improving battery life.

Claims

1. An automatic meter reading (AMR) system comprising:

at least one meter reading device adapted to transmit radio frequency (RF) communications; and

at least one endpoint device having a meter interface module in communication with a meter device that is adapted to receive RF communications, the meter interface module including a digital squelch circuit arrangement adapted to be responsive to an inbound RF communication signal with a target data rate that corresponds to the at least one endpoint, the squelch circuit arrangement further adapted to detect the data rate of a plurality of inbound RF communication signals and determine if the data rate of any of the inbound RF signals matches the target data rate, wherein the meter interface module is adapted to transmit metered data via an RF signal to the at least one meter reading device when data rate of the inbound communication matches the target data rate.

2. The AMR system of claim 1, wherein the RF communications are Manchester-encoded and the digital squelch circuit arrangement is adapted to detect a specific Manchester on-air data rate of the communications that matches the target data rate assigned to the squelch circuit arrangement.

3. The AMR system of claim 1, wherein the RF communications are non-return to zero encoded.

4. The AMR system of claim 1, wherein the RF communications are binary encoded.

5. The AMR system of claim 1, wherein upon detection of an RF inbound signal the squelch circuit arrangement of the meter interface module is adapted to initialize a device timer of the at least one endpoint device and start a communication capture and compare sequence in the at least one endpoint device, the squelch circuit arrangement further adapted to filter inbound signals until a valid communication is detected, wherein a valid communication comprises an inbound signal having a data rate that matches the target data rate, and wherein the squelch circuit arrangement is further adapted to decode and process the valid communication for communication data.

6. The AMR system of claim 5, wherein a filtering arrangement of the squelch circuit arrangement is adapted to filter inbound communications upon detecting a base edge and a second edge so as to identify the second edge as a good edge or a bad edge as a function of a time of the edge, such that

if the second edge is a good edge, a good count register of the filter arrangement is incremented, and

if the second edge is a bad edge, a bad count register of the filter arrangement is incremented and the good count register is cleared;

and clearing the good count register; and

wherein the filter arrangement is adapted to detect and identify subsequent edges as good edges or bad edges until the target data rate is detected.

7. The AMR system of claim 6, wherein the squelch circuit arrangement is further adapted to perform a selectivity test after the second edge and subsequent edges are detected, wherein the selectivity test includes analysis of a time between the base edge and the second edge, a review of the bad count register and a review of the good count register to determine if the bad count register is below a predetermined limit.

8. The AMR system of claim 1, wherein the meter interface module of the endpoint device is adapted to include

an extraction circuit adapted to receive and quantize an incoming data signal;

and

an edge detector circuit adapted to receive a quantized data signal from the extraction circuit and detect edges in the quantized data signal, wherein the edge detector circuit includes a first counter to track a number of good edges and a second counter to track a number of bad edges;

wherein the extraction circuit is adapted to pass a recovered clock signal and a recovered data signal to the edge detector circuit when the first counter reaches a first predetermined value, and wherein the extraction circuit is adapted to reject the incoming data signal when the second counter reaches a second predetermined value.

9. The AMR system of claim 8, further comprising a divider circuit adapted to derive a plurality of clock frequencies and pass at least one frequency to the extraction circuit and to the edge detector circuit.

10. A method for communicating with at least one endpoint device in an automatic meter reading (AMR) system, wherein the at least one endpoint device includes a meter device and a meter interface module adapted for radio frequency (RF) communications, the method comprising the steps of:

initializing a device timer of a digital squelch circuit arrangement of the meter interface module at least one endpoint device, wherein the squelch circuit arrangement is configured to respond to a target data rate;

starting a communication capture and compare sequence in the squelch circuit arrangement of the at least one endpoint device;

filtering inbound RF communication signals at the at least one endpoint device until a valid communication is detected, wherein a valid communication comprises the inbound RF communication signal with a data rate that matches the target data rate;

decoding the valid communication for communication data; and

processing the communication data.

11. The method of claim 10, wherein the step of filtering incoming communications further comprises:

detecting a base edge;

detecting a second edge and identifying the second edge as a good edge or a bad edge based upon a time of the edge,

if the second edge is a good edge, incrementing a good count register,

if the second edge is a bad edge, incrementing a bad count register; and

detecting and identifying subsequent edges as good edges or bad edges until the target data rate is detected, until determining the target data rate is not present, or until a predetermined acquisition timeout is reached.

12. The method of claim 11, further comprising the step of:

performing a selectivity test after the second edge and subsequent edges are detected, wherein the selectivity test includes;

analyzing a time between the base edge and the second edge;

reviewing the bad count register; and

reviewing the good count register if the bad count register is below a predetermined limit.

13. The method of claim 10, wherein the step of starting a communication capture and compare sequence includes detecting and receiving inbound RF communications.

14. The method of claim 13, wherein the inbound RF communications are Manchester-encoded and the target data rate comprises a specific Manchester on-air data rate.

15. The method of claim 13, wherein the inbound RF communications are non-return to zero encoded.

16. The method of claim 13, wherein the inbound RF communications are binary encoded.

17. An endpoint meter device for use in an automatic meter reading system, wherein the endpoint meter device includes a meter interface module adapted to filter inbound radio frequency (RF) communication signals received from a meter reading device, the endpoint meter device comprising:

an extraction circuit adapted to receive and quantize an incoming data signal; and

an edge detector circuit adapted to receive a quantized data signal from the extraction circuit and detect edges in the quantized data signal, wherein the edge detector circuit includes a first counter to track a number of good edges and a second counter to track a number of bad edges;

wherein the extraction circuit is adapted to pass a recovered clock signal and a recovered data signal to the edge detector circuit when the first counter reaches a first predetermined value, and wherein the extraction circuit is adapted to reject the incoming data signal when the second counter reaches a second predetermined value.

18. The device of claim 17, wherein the inbound data signal comprises a wireless radio frequency (RF) communication.

19. The device of claim 18, wherein the RF communication is Manchester-encoded.

20. The device of claim 18, wherein the RF communication is non-return to zero encoded.

21. The device of claim 18, wherein the RF communication is binary encoded.

22. The device of claim 17, further comprising a divider circuit adapted to derive a plurality of clock frequencies and pass at least one frequency to the extraction circuit and to the edge detector circuit.

23. A digital squelch circuit arrangement adapted for use with a meter interface module of an automatic meter reading (AMR) system, the squelch circuit arrangement comprising:

means for detecting an inbound radio frequency (RF) data signal having a data rate, wherein the data rate is represented by a series of edges and wherein the squelch circuit arrangement is adapted to be responsive to a target data rate;

means for detecting edges within the inbound RF data signal;

means for determining the data rate of the inbound data signal as a function of the detected edges and determining if the data rate of the inbound data signal matches the target data rate of the squelch circuit arrangement; and

means for processing the data within the data signal if the data rate matches the target data rate.

24. The endpoint device meter interface module of claim 23, wherein said inbound data signal detection means includes an extraction circuit, and wherein said means for detecting edges within the inbound data signal comprises a digital squelch circuit arrangement that includes an edge detector circuit adapted to receive a quantized data signal from the extraction circuit and detect edges in the quantized data signal, wherein the edge detector circuit includes a first counter to track a number of good edges and a second counter to track a number of bad edges.