FIELD OF THE INVENTION
The present invention relates to a method of automatic calibration and
configuration of acoustic sensors for steam tube leak detection in power and
process plants.
The invention further relates to an apparatus for automatic calibration and
configuration of acoustic sensors to provide a secure means to perform the
configuration and calibration operations.
BACKGROUND OF THE INVENTION
Acoustic sensors are used to detect leaks in advance to enable corrective
measures to avoid secondary damages in power or process plants. Tube failures
are considered as one of the major causes for any boiler outage. If the leakage
of steam from the boiler tube could be detected at an early stage of operation, a
planned series of correction measures can be taken up to avoid serious
secondary damages.
To cover the entire plant, a multitude of sensors, usually 12-30, are employed all
over the plant structure. There is a need for configuring the sensors (sensor id,
network address, settings sensor type, etc) at the time of initial installation as
well as at the time of replacement of a sensor.

Periodic calibration of the sensors is required for effective functioning of the leak
detection system. The process of calibration may become tedious and error
prone when the multiple sensors at different locations and/or different calibration
intervals are considered. Further, problems are faced while replacing one faulty
sensor with a new replacement sensor. The configuration data from a faulty
sensor may need to be fed to the new sensor which interalia requires one to
have the faulty sensor online, note down the configuration data, remove the
faulty sensor, introduce the new sensor and copy all the configuration data to
the new sensor. Additionally, managing the multitude of sensors via calibration
or maintenance schedules require logging/tracking of data as to when the
sensors were configured/ calibrated. The present invention deals with
automating and easing the configuration and calibration processes.
Patent Application WO 2005071371 Al, describes an automatic calibration .
method of a sound level meter and its, system in which calibration of a sound
level meter can be carried out accurately and reliably. In the system for
calibrating the sound level meter automatically by means of an acoustic
calibrator, the acoustic calibrator comprises a means for generating a code signal
by sound, and a means for generating a calibrated sound pressure, and the
sound level meter comprises a means for identifying the code signal, a means for

making a switch to a calibration mode based on a code signal identified by the
code signal identifying means, a means for regulating the gain of an amplifier
such that an indicated value in the calibration mode corresponds to the level of a
calibrated sound pressure, and a means for recording the data of calibration, the
calibrated sound pressure, the type and production number of the acoustic
calibrator, and the like.
Patent Application, EP 2626755 Al, describes a calibration method, calibration
device and measurement device, wherein : a calibration is brought into close
proximity of the measurement device such that a data communication link is
established between the measurement device and the calibration device; wherein
the following steps are performed while the calibration device and the
measurement device are in close proximity of each other: the calibration device
performs a measurement of at least one physical phenomenon; the
measurement device performs a measurement of the same physical
phenomenon; the result of the measurement by the measurement device is
compared with the result of the measurement of the calibration device; and
calibration parameters are computed based on a difference between the result of
the measurement by the measurement device and the result of the
measurement by the calibration device.

Patent Application, WO 2009044228 A2, describes a device and a method for
programming the read/writeable memory of the Radio Frequency Identification
(RFID) circuitry by communications between either RF antenna or bus
communications port controller interface or both. In a peripheral device, an
Electronically Erasable Programmable Read Only Memory (EEPROM), bus
communications controller interface, Near Field Communication (NFC) interface,
antenna and logic controller operate to receive and transmit configuration and
calibration data between a Bluetooth circuit and an external device. The dual
interfaced EEPROM shares or partitions its EEPROM between the Bluetooth circuit
and the external device.
Patent Application, WO 2006133204 A2, describes powering devices using RF
energy harvesting, an apparatus for an application including a core device for the
application. The apparatus includes a power (preferably RF energy) harvester
connected to the core device to power the core device. Also disclosed is a
method for an application. The method includes the steps of converting RF
energy into usable energy. There is the step of powering the core device with
the usable energy.

Thus, the prior arts disclose of methods for automatic calibration of sound level
meters, calibration using proximity, dual port memory and energy harvesting
individually. The present invention deals with a method and apparatus for
automatic configuration and calibration of acoustic sensors using Radio
Frequency Identification (RFID) / Near Field Communication (NFC) technology in
a dual port memory with energy harvesting.
OBJECTS OF THE INVENTION
It is an object of the invention to propose a method of automatic calibration and
configuration of acoustic sensors for leak detection in power and process plant.
Another object of the invention is to propose a method of automatic calibration
and configuration of acoustic sensors for leak detection in power and process
plant which eases sensor replacement by allowing configuration of the sensor
even without its power supply.
A further object of the invention is to provide a secure means to perform the
configuration and calibration.

A still further object of the invention is to propose a method of automatic
calibration and configuration of acoustic sensors for leak detection in power and
process plant which allows maintenance/ inventory management of the sensors.
SUMMARY OF THE INVENTION
Accordingly there is provided a method and an apparatus for automatic
configuration and calibration of acoustic sensors. The apparatus and the sensor
having wireless interface, especially, Radio Frequency Identification (RFID) or
Near Field Communication (NFC), and microcontrollers at both ends - sensor as
well as the apparatus. The near field wireless communication is utilized for
communicating the test conditions and a feedback between the sensor and the
apparatus.
The sensor has an energy harvesting sub-circuit, specifically Radio Frequency
(RF) energy harvesting and a RF interface connection to the microcontroller. The
energy harvesting is used to power up sensors even when taken off-line and the
apparatus reads off the configuration- parameters. The apparatus can now
configure a replacement sensor with configuration data read from an off-line

sensor. The replacement sensor can be powered using the energy harvesting
feature again. Thus the complexity of replacing sensors and configuring
replacement sensors is eliminated.
The apparatus has means of generating single/ multiple test condition(s) and
communicating the current test condition to the sensor using the RF interface.
The sensor adjusts its gain using this information automatically and provides a
calibration complete feedback through the RF interface. This leads to an
automatic calibration procedure.
After the configuration/ calibration is complete, the date, time and sensor IDs
can be logged in the apparatus and stored locally and/or sent to a PC/ remote
control system using wired/ wireless communication means. This helps in
tracking the changes made to the sensor and helps in inventory/ maintenance
management. * '
The RF interface between the sensor and the apparatus being near field
communication state, the apparatus provides a primary level securing. Further,
by having a password protected/ encrypted, the communication interface
between the sensor and the apparatus, additional security is ensured.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 illustrates an apparatus of an exemplary embodiment of the invention;
Figure 2 illustrates another embodiment apparatus of the invention;
Figure 3 illustrates a flow chart of one aspect of the configuration according to
method of the invention.
Figure 4 illustrates a flow chart of another aspect of the calibration of the
method.
Figure 5 illustrates a flow chart of still another aspect of automatic replacement-
configuration of the method.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF THE
INVENTION
The system for automatic configuration and calibration of acoustic sensors is
shown in Figure 1. The apparatus (100) of the system consists of a
microcontroller/ processor (101) interfaced to a transducer (102), a wireless/ RF
transceiver (103), a display (104), a keypad (105), a memory device (106) and a

secondary interface (107). The display (104) and the keypad (105) are used in
selected modes such as configuration, calibration, and replacement-
configuration. The memory device (106) is used to log the configuration/
calibration events. The secondary interface (107) may be a wired interface- such .
as but not limited to USB, RS232, RS485 or wireless interface- Wifi, Bluetooth,
and used to transfer the logs, to a remote control device or a PC for further
processing/ management. During the configuration mode, the parameters stored
in the memory or the parameters derived after modifications using the display
and keypad, are transferred to the sensor (109) via the wireless interface (107).
During the calibration mode, the controller (101) with the transducer (102) is
able to generate different test patterns or sequence, each having a
corresponding digital code which gets shared via the wireless interface (107) for
performing auto calibration. During the replacement-configuration mode, the
apparatus first reads configuration data from the sensor (109) to be replaced
and stores it in its memory (106) and then proceeds to configuration mode to
configure the replacement sensor. The apparatus stores logs of all events with
fields for example, sensor ID, sensor address, type, date, and time. The
apparatus optionally includes, a Real Time clock for logging data, time of events.
A coupling (108), is provided for coupling of the apparatus to the sensor (109).

The sensor, (109) consists of a microcontroller/ processor (110) interfaced to the
sensor element (111), with its associated amplification circuitry (112), an analog
to Digital Converter (113), a programmable gain adjuster (114), a wireless/ RF
transceiver (115), a display or indication (117) and a memory device (118). The
sensor (109) can be powered using conventional means as well as and energy
harvesting means (116). The display/ indication are used to indicate the user,
the mode of operation, measured parameter or status. The memory device is
used to store the parameters, log errors/ status information and the
configuration/ calibration events. The sensor operates in its normal mode while
polling for wireless communication at intervals / waiting for an interruption from
the wireless transceiver (115). Once communication with the apparatus is
established, the mode of operation set at the apparatus is entered. During the
configuration mode, the sensor (109) gets programmed with the configuration
parameters obtained via the wireless interface (107). During the calibration
mode, the sensor (109) is informed about the test pattern/ sequence code and
the sensor (109) processes the input from the sensor element (11) and tries to
match the levels pre-defined by the test code by using the programmable gain
adjuster (114). During the replacement-configuration mode, the sensor (109)
allows the calibrator to read its configuration information. The sensor (109) may
also include a Real Time clock for logging date, time of events. The sensor may
also include a keypad for input provision.

Figure 2, illustrates a preferred embodiment of the invention, where the primary
differences from figure 1 are: usage of a NFC dual port EEFROM with energy
harvesting (115), in place of the memory, RF transceiver and energy harvesting
sub-sections in Figure 1; usage of a speaker as the transducer and a microphone
as the sensor element. One part which is suitable for (115) is STMicro electronics
M24LRxxE series of dual port memories. Other equivalents/ combinations may
also be employed to achieve energy harvesting with RF interface. The RF
transceivers may involve a password protected/ encrypted means to ensure
security whereby communication is established only if the password is correct.
Figure 3 illustrates the flow chart of steps in the automatic configuration mode
of operation. First the apparatus is powered on and the mode set to
configuration using the display and keypad. The sensor and the apparatus are
brought into close proximity so as to establish communication between them.
The sensor stops normal mode of operation and enters into configuration mode.
The apparatus now sends configuration data via the wireless interface and the
sensor gets programmed with the same. The sensor now gives a configuration
complete feedback to the apparatus which then logs the date, time, sensor ID,
etc. of the configured sensor. The sensor is now removed from close proximity to
the calibrator and the sensor reverts to normal mode of operation.

Figure 4, illustrates the flow chart of steps in the automatic calibration mode of
operation. First the apparatus is powered on and the mode set to calibration
using the display and keypad. The sensor and the apparatus are brought into
close proximity so as to establish a communication between them. The sensor
stops normal mode of operation and enters into calibration mode. The test
pattern/ sequence is selected at the apparatus which now sends corresponding
digital code via the wireless interface and the sensor gets knowledge of the input
level. The apparatus generates the selected test pattern/ sequence using its
transducer/ speaker and the sensor processes this input after it passes its gain,
, ADC stages. The sensor adjusts the programmable gain/ coefficients to get the
known level. The sensor now give a calibration complete feedback to the
calibrator which then logs the date, time, sensor ID, etc. of the configured .
sensor. The sensor is now removed from close proximity to the apparatus and
the sensor reverts to normal mode of operation.
Figure 5, illustrates the flow chart of steps in the automatic replacement-
configuration mode of operation. First the apparatus is powered on and the
mode set to replacement-configuration using the display and keypad. The sensor
to be replaced and the apparatus are brought into close proximity so as to
establish a communication between them. The sensor stops normal mode of
operation and enters replacement mode. The sensor allows the apparatus to
read the configuration parameters. The apparatus stores the parameters in its

memory. The sensor to be replaced is now removed from close proximity of the
apparatus and the sensor reverts to normal mode of operation. The replacement .
sensor and the apparatus are brought jnto close proximity so as to establish a
communication between them. The sensor stops normal mode of operation and
enters into configuration mode. The apparatus now sends the stored
configuration data via the wireless interface and the sensor gets programmed
with the same. The sensor now gives a configuration complete feedback to the
apparatus which then logs the date, time, sensor ID, etc of the configured
sensor. The sensor is no removed from close proximity of the apparatus and the
sensor reverts to normal mode of operation.

WE CLAIM :
1. A method for automatic configuration of acoustic sensors comprising the
steps of: ,
- selecting a configuration mode in an apparatus having a wireless
interface;
- placing the sensor having a matching wireless interface in proximity to the
apparatus;
- establishing a communication between the sensor and the apparatus;
- allowing the sensor to switch over from operational mode to configuration
mode;
- configuring the sensor based on the configuration data derived from the
apparatus;
- receiving configuration - completion feed back signal from the sensor;
- logging of date, time, sensor ID, of the configured sensor at the
apparatus;
- removing the sensor from proximity of the apparatus; and
- causing the sensor to revert to normal mode of operation.

2. A method for automatic calibration of acoustic sensors comprising the
steps of :
- selecting a calibration mode at an apparatus having an wireless
interface;
- placing the sensor having a corresponding wireless interface in proximity
of the apparatus;
- establishing a communication between the sensor and the apparatus;
- allowing the sensor to switch over from operational mode to calibration
mode;
- selecting a test pattern/ sequence at the apparatus and communicating
the test pattern/ sequence code to the sensor;
- generating the selected test pattern/ sequence at the apparatus and
processing the test pattern/ sequence as input at the sensor;
- adjusting of gain/ coefficients at the sensor based on the processed test
pattern and the signal input;

- transmitting a calibration complete feedback from the sensor to the
apparatus;
- logging of date, time, sensor ID, of the calibrated sensor at the apparatus;
and
- removing the sensor to revert to normal mode of operation.
3. A method for automatic replacement-configuration of acoustic sensors
comprising the steps of:
- setting a replacement mode at an apparatus having an wireless interface;
- placing the sensor to be replaced having equivalent wireless interface in
proximity to the apparatus;
- establishing a communication between the sensor and the apparatus;
- allowing the sensor to switch over from normal mode of operation to the
replacement mode;

- saving the configuration date from the original sensor at the apparatus
including removing the sensor from the proximity of the apparatus;
- placing the replacement sensor in proximity of the apparatus;
- establishing a communication between this sensor and the apparatus and
allowing the new sensor to switch over to configuration mode;
- programming the sensor with configuration data from apparatus and
receiving a configuration completion report from the new sensor;
- logging of date, time, sensor ID, of the replaced/ configured sensor at the
apparatus; and
- removing the replaced sensor from proximity of the apparatus and
causing the sensor to revert to normal mode of operation.
4. The method as claimed in any of the preceding claims further including a
step of providing a security through encrypted/ password protected
communication between the sensor and the apparatus.

5. The method as claimed in any of claims 1 to 3, comprising an energy
harvesting means at the sensor to have configuration, calibration,
configuration on replacement without being powered on.
6. The method as claimed in any of claims 1 to 3, comprising a logging
means.
7. The method as claimed in any of claims 1 to 3, comprising a step of
configuring Real Time Clock at the sensor through a wireless interface
of the apparatus.
8. A system for automatic configuration and calibration of acoustic
sensors comprising:-
at least a sensor with wireless interface and a microcontroller having
means to automatically adjust gains/ coefficients based on a test
pattern/ sequence including a processed input from a sensor element
of said sensor;
an apparatus with an wireless interface; microcontroller having multiple
test patterns/ sequences for each test condition, means to select a

mode of operation from a group consisting of configuration, calibration,
and replacement wherein the test pattern/ sequence is input to the
sensor for calibration; and a speaker for generation of the selected test
pattern/ sequence.
9. A system for automatic configuration and calibration of acoustic
sensors as claimed in claim 8, wherein the sensor comprises a dual
port memory to achieve the RF interface and store logs and diagnostic
information.
10. A system for automatic configuration and calibration of acoustic
sensors as claimed in claim 8, wherein the sensor comprises an energy
harvesting sub circuit, enabling configuration/ calibration/ replacement
without having power supply.
11. A system for automatic configuration and calibration of acoustic
sensors as claimed in claim 8, wherein the RF interface is Near Field
Communication enabling diagnostics via mobile applications.

12. A system for automatic configuration and calibration of acoustic
sensors as claimed in claim 8, wherein apparatus and/or sensor has
memory device to store configuration/ calibration replacement logs,
diagnostic etc.
13. A system for automatic configuration and calibration of acoustic
sensors as claimed in claim 8, wherein the apparatus and/or sensor
has real time clocks to log time events.
14. A system for automatic configuration and calibration of acoustic
sensors as claimed in claim 8, wherein the apparatus has means to
transfer the stored logs to a remote control system.

ABSTRACT

The invention relates to a method and a system for automatic configuration and
calibration of acoustic sensors employing acoustic sensors and an apparatus with
a wireless/ RF interface. The sensor has an energy harvesting sub-circuit, to
power up faulty sensor modules even when taken off-line while the apparatus
can read off the configuration parameters and programs the replacement sensor
through the wireless interface. The apparatus has means for generating single/
multiple test condition(s) and communicating the current test condition to the
sensor using the wireless interface. The sensor adjusts its gain using this
information automatically and provides a calibration complete feedback through
the wireless interface. After the configuration/ calibration is complete, the date,
time and sensor IDs can be logged in the apparatus and stored locally and/or
sent to a PC/ remote control device using wired/ wireless communication means.
Further by having a password protected/ encrypted communication interface
between the sensor and calibrator, a secure means of automatic configuration
and calibration is made possible.