Distributed sigma-delta sensor network

• US 7,456,770 B2
• Filed: 03/02/2007
• Issued: 11/25/2008
• Est. Priority Date: 03/02/2007
• Status: Expired due to Fees

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Cairns, Douglas A.
• Primary Examiner(s): Nguyen; Khai M
• Application Number:
  US11/681,213
• Publication Number:
  US 20080211704A1
• Time in Patent Office: 634 Days
• Field of Search: 341/143, 341/155
• US Class Current: 341/143
• CPC Class Codes: H03M 3/462 Details relating to the decimation process decimation filters in general H03H17/0416, H03H17/0621
• CPC Class Codes: H03M 3/468 Interleaved, i.e. using multiple converters or converter parts for one channel, e.g. using Hadamard codes, pi-delta-sigma converters
• 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

The sensor network described herein uses a distributed sigma-delta converter, where each of a plurality of sensor nodes includes a sigma-delta modulator communicatively coupled to a remotely located sigma-delta processor in a control hub. Each sensor node generates a serial bit stream representative of a sensor output signal. The control hub includes a plurality of signal processors, each of which receive and digitally process the serial bit stream wirelessly transmitted by a corresponding sensor node. A controller in the control hub analyzes the digital output from each signal processor to determine one or more characteristics of the sensor network.

Claims

1. A plurality of sensor nodes for a sensor network, each sensor node comprising:

a sensor configured to sense at least one characteristic of the environment of said sensor network;

a sampling circuit configured to oversample an input signal at a predetermined sample rate;

a sigma-delta modulator configured to generate a serial bit stream based on the oversampled input signal; and

a communication circuit to transmit said serial bit stream to a corresponding sigma-delta processor in a remote control hub comprising a sigma-delta processor for each sensor node.

2. The sensor node of claim 1 wherein the sigma-delta modulator comprises:

a summing node to generate an error signal based on the input signal and a feedback signal;

an integrator to generate an integrated signal based on the error signal; and

a quantizer configured to quantize the integrated signal to generate the serial bit stream.

3. The sensor node or claim 2 further comprising a digital-to-analog converter to convert said serial bit stream into analog form to generate said feedback signal.

4. The sensor node of claim 1 wherein the sigma-delta modulator comprises a first order sigma-delta modulator.

5. The sensor node of claim 1 wherein the sensor comprises one of a motion sensor, audio sensor, temperature sensor, humidity sensor, wind sensor, pressure sensor, vibration sensor, chemical sensor, and light sensor.

6. The sensor node of claim 1 wherein each sensor in the sensor network is configured to sense a different environmental characteristic.

7. A method of providing digital data from a plurality of sensor nodes to a remote control hub comprising a sigma-delta processor for each sensor node, the method comprising:

oversampling a sensor node input signal at each sensor node at a predetermined sample rate to generate an oversampled signal;

performing sigma-delta modulation on the oversampled input signal in each sensor node to generate a serial bit stream for each sensor node; and

transmitting each serial bit stream to the corresponding sigma-delta processor in the remote control hub.

8. The method of claim 7 wherein performing sigma-delta operations comprises:

generating an error signal based on the input signal and a feedback signal;

generating an integrated signal based on the error signal; and

quantizing the integrated signal to generate the serial bit stream.

9. A control hub communicatively coupled to a plurality of sensor nodes in a sensor network, said control hub comprising:

a plurality of sigma-delta processors, each of said sigma-delta processors corresponding to a sigma-delta modulator in one of the sensor nodes and configured to generate an output signal based on a serial bit stream received from a corresponding sensor node; and

a controller configured to analyze the output signals from each sigma-delta processor to determine one or more characteristics of the environment of said sensor network.

10. The control hub of claim 9 wherein each sigma-delta processor comprises a filter configured to:

lowpass filter the serial bit stream received from the corresponding sensor node; and

decimate the filtered bit stream to generate the output signal.

11. The control hub of claim 9 wherein each sigma-delta processor comprises:

a filter configured to lowpass filter the serial bit stream received from the corresponding sensor node; and

a decimator configured to decimate the filtered bit stream to generate the output signal.

12. The control hub of claim 9 wherein each sigma-delta processor further comprises a communication circuit to receive the serial bit stream from the corresponding sensor node.

13. The control hub of claim 9 further comprising one or more communication circuits configured to receive the serial bit streams from each sensor node and to provide each bit stream to the corresponding sigma-delta processor.

14. A method of digitally processing digital data provided by a plurality of sensor nodes in a sensor network, the method comprising:

receiving a plurality of serial bit streams from corresponding sensor nodes in the sensor network;

performing separate sigma-delta processing operations on each of said received serial bit streams to generate an output signal; and

analyzing the output signals to determine one or more characteristics of the environment of the sensor network.

15. The method of claim 14 wherein performing separate sigma-delta processing comprises:

filtering the serial bit stream received from a corresponding sensor node; and

decimating the filtered bit stream to generate the output signal.

16. A sensor network comprising:

a plurality of sensor nodes, wherein each sensor node comprises a sigma-delta modulator configured to generate a serial bit stream based on an oversampled sensor input signal; and

a control hub communicatively coupled to the plurality of sensor nodes and comprising a plurality of sigma-delta processors, wherein each sigma-delta processor corresponds to a different sensor node and is configured to generate an output signal based on the serial bit streams received from a corresponding sensor node.

17. The sensor network of claim 16 wherein each of said sensor nodes further comprises:

a sampling circuit configured to oversample the input signal at a predetermined sample rate to generate the oversampled input signal; and

a communication circuit to transmit said serial bit stream to the corresponding sigma-delta processor in the control hub.

18. The sensor network of claim 16 wherein the control hub further comprises a controller configured to analyze the output signals from each sigma-delta processor to determine one or more characteristics of the environment of said sensor network.

19. A method of processing signals in a sensor network comprising a plurality of sensor nodes communicatively coupled to a control hub comprising a plurality of sigma-delta processors, the method comprising:

performing sigma-delta modulation on oversampled input signals to generate a serial bit stream at each sensor node;

transmitting each serial bit stream to a corresponding sigma-delta processor in the control hub;

performing separate sigma-delta processing operations on each serial bit stream received at the control hub to generate an output signal corresponding to each sensor node; and

analyzing the output signals to determine one or more characteristics of the environment of the sensor network.

20. The method of claim 19 wherein each sensor node is configured to sense a different environmental characteristic.