Frequency shift compensation, such as for use in a wireless utility meter reading environment

• US 8,395,528 B2
• Filed: 08/08/2011
• Issued: 03/12/2013
• Est. Priority Date: 03/30/2004
• Status: Active Grant

• Current Assignee: Itron, Inc.
• Original Assignee: Itron, Inc.
• Inventors: Cahill-O'Brien, Barry, Cornwall, Mark K.
• Primary Examiner(s): WONG, ALBERT KANG
• Application Number:
  US13/205,081
• Publication Number:
  US 20110291856A1
• Time in Patent Office: 582 Days
• Field of Search: 34087002-87003, 455/266, 334/40, 375/240, 375/344
• US Class Current: 340/870.03
• CPC Class Codes: G01D 4/002 Remote reading of utility meters
• CPC Class Codes: H04L 1/0036 arrangements specific to the receiver
• CPC Class Codes: H04L 2027/0065 Frequency error detectors H04L2027/0067 takes precedence
• CPC Class Codes: H04L 27/14 Demodulator circuits; Receiver circuits
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 20/30 Smart metering, e.g. specially adapted for remote reading

Abstract

Methods and apparatus for computing the carrier frequency of a transmitter using frequency modulated digital data to compensate for frequency shifting of the transmitter and the receiver local oscillators and for bandwidth adjustment of the receiver'"'"'s filter. In particular, methods and apparatus are disclosed for binary systems transmitting “1” and “0” data using decoded or undecoded received signals.

Claims

1. In a wireless communication network, a method comprising:

receiving a first signal representing a first coded value, wherein the first signal is transmitted at a transmitter carrier frequency, and wherein a transmitted signal includes coded values to modulating the transmitter carrier frequency;

mixing the first signal with a receiver carrier frequency, wherein the receiver carrier frequency an estimation of the transmitter carrier frequency;

receiving a second signal representing a second coded value;

mixing the second signal with the receiver carrier frequency;

computing a difference between the transmitter carrier frequency and the receiver'"'"'s carrier frequency based only on the two mixed signals without need for an initial training period; and

adjusting a bandwidth of a receiver variable filter around the receiver carrier frequency.

2. The method of claim 1, wherein the coded values are binary, and wherein the method further comprises centering the receiver carrier frequency to match the transmitter carrier frequency.

3. The method of claim 1, wherein one of the first and second mixed signals is a baseband in-phase signal and the other first and second mixed signal is a baseband quadrature signal.

4. In a utility meter data transmission system, a variable bandwidth receiver comprising:

a receiver module for receiving two binary data signals or a single data symbol signal, wherein data values are frequency modulated by adding to and subtracting from a transmitter carrier frequency in case of the two binary data signals and are frequency modulated by adding to or subtracting from a transmitter carrier frequency in case of the single data symbol signal;

a variable filter for filtering received signals;

a mixer for down- or IF-converting the received signals;

a processor for computing a difference between the transmitter carrier frequency and the receiver carrier frequency based on the down- or IF-converted signals without need for an initial training period; and

a controller for generating compensation signal for adjusting the filter bandwidth based on the computed difference.

5. The variable bandwidth receiver of claim 4, wherein adjusting the bandwidth comprises:

centering the bandwidth around a frequency substantially similar to the transmitter'"'"'s frequency;

narrowing the bandwidth; and

transmitting subsequent data at a higher rate than a previous data rate.

6. The variable bandwidth receiver of claim 4, wherein a transmitter transmits the at least one or two signals at a first data rate, during an initial adjustment period, and subsequently transmits data at a higher data rate than the first data rate, during a normal data transfer period, and wherein the receiver widens the receiver filter bandwidth during the initial adjustment period and narrows the bandwidth during the normal data transfer period.