Note: Descriptions are shown in the official language in which they were submitted.
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PORTABLE RADIOMETRIC DATA ACQUISITION SYSTEM
1 BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to radiometric data
acquisition systems and more particularly to a portable
radiometric data acquisition system that can be used as a
fire sensor.
2 Discussion
Data acquisition systems are employed to detect and
record ambient environmental data such as radiometric,
photometric and temperature data. In addition, data
acquisition systems can be used to collect and record
information from other sensors such as pressure,
acceleration, flow, etc. Prior radiometric data
acquisition systems are generally bulky and do not
function well in harsh environments. These prior
systems typically included a sensor which would be placed
in the desired location to be sensed, with wires
connecting the sensor to an amplifier and further wiring
connecting the amplifier to a recorder. This
configuration results in systems which require
considerable space as well as conditioned power.
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1 These disadvantages have limited the usefulness of
prior radiometric data acquisitions systems. For
example, when prior radiometric data acquisition systems
were placed in a vehicle, the vehicle sometimes could not
be operated in its normal operating mode because the
system would require personnel to monitor it and and also
the system might not withstand the harsh environment of
the vehicle under operation. Another disadvantage is
that the bulk of such systems prevented them from being
used in certain confined areas. Even where space is
available, the cabling necessary to connect the various
components might prevent normal operation of the vehicle.
It is another disadvantage with prior radiometric
data acquisition systems that they require frequent
attention and cannot be left for extended periods of time
unattended.
Thus it would be desirable to provide a radiometric
- data acquisition system which is small and portable so
that it can operate in a confined space. Also it would
be desirable to provide a data acquisition system that
can operate unattended for long periods of time. It is
further desirable to provide a data acquisition system
which can withstand harsh environments and not interfere
with the normal operation of the surrounding apparatus.
Fire sensors are devices which detect radiometric
information from one or more sensors and process this
information to determine if it is indicative of a fire.
Microprocessor controlled fire sensors have been
developed to reduce the size of the system and to refine
the analysis of the sensor data and thereby improve the
detection of fires and the avoidance of false detections.
See, for example, U.S. Patents No. 4,~79,156 and
4,769,775, both issued to M. T. Kern et al. However,
while such systems are able to successfully detect the
existence of fire, once the fire is extinguished, a great
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1 deal of effort goes into trying to determine the
cause of the fire. The fire sensor merely signal~ that
there was a fire but does not provide any information
regarding the cause of the fire. Thus, it would be
desirable to provide a fire sensor which can also provide
information useful in determining the cause of the fires
it detects.
SUMMARY OF THE INVENTIOM
The present invention is a portable radiometric data
acquisition system that is capable of collecting and
storing data from sensors. The sensors may be located in
a single or a plurality of locations and may sense such
environmental information as radiometric, photometric,
and temperature data, and/or other types of information
such as pressure, acceleration, flow, etc. Because of
its small size (a self-contained embodiment may fit in
the palm of one's hand) the present invention can be
placed in areas of difficult access. It can also operate
unattended for extended periods of time without
interfering with the surrounding vehicle or equipment.
The data acquisition system according to the present
invention utilizes a microprocessor with one or more
detectors connected to its input. The detector signal
may be amplified and connected to an analog to digital
converter before being transmitted to the CPU of the
microprocessor. The microprocessor contains read only
memory, random access memory and erasable programmable
read only memory. The program for the CPU may be
contained, in part, in both the read only memory and the
erasable programmable read only memory. Typically,
subroutines will be contained within the read only
memory. The data acquisition system may be programmed
through the erasable programmable read only memory to
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1 accept and store detected data at predetermined intervals
of time. The frequency of the storing of detected data
will depend on the application and may vary widely.
In one embodiment, the portable data acquisition
system is adapted to be used as a fire sensor. In this
embodiment, the detector, or detectors, are chosen and
the detector signals processed to yield the desired
information indicative of a fire. In this way, the
portable radiometric data acquisition system of the
present invention not only can detect a fire but also
record environmental parameters leading up to the fire.
This information is particularly useful to assist in
investigations of the cause of the fire.
BRIEF DESCRIPTION OF THE DRAWINGS
The various advantages of the present invention will
become apparent to one skilled in the art by reading the
following specification and by reference to the following
drawings in which:
FIG. 1 is a block diagram of the preferred
embodiment of the portable data acquisition system of
this invention;
FIG. 2 ~s a flow diagram of the portable data
acquisition system program for storing data; and
FIG. 3 is a flow diagram of a program for the
portable data acquisition system as employed in a fire
detection system.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A data acquisition system according to the present
invention is shown in FIG. 1. The portable data
acquisition system 10 is shown controlled by a
microprocessor 12. This microprocessor 12 may be, for
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1 example, a Motorola MC68HCll. In this embodiment, the
microprocessor 12 is connected to four detectors. First
and second radiometric detectors, 14 and 16,
respectively, are capable of sensing radiation of a
wavelength of a particular spectral band. Theæe
detectors are also capable of producing an anaiog signal
that is proportional to the detected energy. The
detection of two discrete regions of wavelengths may be
accomplished, for example, by utilizing identical
detectors for the first and second detectors 14 and 16,
and then placing appropriate filters 18 and 20 in front
of each detector 14 and 16. Each filter 14 and 16 will
then filter out all but the desired wavelengths of
energy. Alternatively, different kinds of detectors with
inherently different spectral sensitivities may be
employed.
In addition, a temperature sensor 22 is also
connected to the microprocessor 12 input. The
temperature sensor 22 is capable of producing an analog
signal that is proportional to the surrounding
temperature. The data acquisition system 10 also is
capable of accepting signals from a fourth detector ~not
shown) along an external sensor line 24. The external
detector may be located at a point remote from the data
acquisition system 10. Depending on the application, the
external sensor may sense information such as pressure,
acceleration, flow, etc., and transmit an analog signal
to the external sensor line 24.
Since the signal along the external sensor line 24
may not be of sufficient strength for processing by the
microprocessor 12, the signal is amplified by an
amplifier 26 which has its output connected to one input
l~ne 28 of the microprocessor 12.
Likewise, the first detector 14 output is connected
along conductor 30 to an amplifier 32 which is connected
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1 to a microprocessor input 34. The second detector 16
output is connected along conductor 36 to an amplifier 38
which transmits ifs output to a microprocessor input 40.
Finally, the temperature sensor 22 output is fed along
conductor 42 to an amplifier 44 which is connected to an
input 46 of the microprocessor 12.
The analog signals from the detectors must be
digitized for processing by the microprocessor 12. Thus,
a series of analog to digital converters 48, 50, 52 and
54 respectively, are connected to the four input lines
34, 40, 46 and 28. The digitized signals produced by the
analog to digital converters are then transmitted to a
CPU 56 for processing.
As shown in FIG. 1, the microprocessor 12 also
includes a program line 58 which is used to put the CPU
into the programming mode for loading programs into the
microprocessor 12 as will be discussed in more detail
below. The program for the CPU is stored in both a read
only memory (ROM) 60 and an electrically erasable
programmable read only memory (EEPROM) 62. Typically the
ROM 60 will be programmed with the communications program
routines and the EEPROM 62 will contain the programming
routines. By the use of subroutines that are stored in
the ROM 60 the program space required for the EEPROM 62
is kept to a minimum. In addition, a random access
memory (RAM) 64 is provided for storing of both data and
program information.
A serial communication interface 66 is provided in
the microprocessor 12 to input and retrieve data from the
CPU 56. The serial communication interface 66 is
connected to a status/data line 68 and to an
interrogate/data line 70. The serial communication
interface 68 is also connected to the CPU 56.
When the program line 58 is held low, the CPU 56 is
placed under the control of the ROM 60 program and the
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1 serial communication interface 66 can be used to input
and retrieve data from the CPU 56. In addition, with the
program line 58 low, programs can be loaded in the EEPROM
62 by means of an industrial standard RS-232 port from
any external source which is connected to the status/data
line 68. A status line 72 is also provided which can be
programmed to provide an output to external signaling or
activation devices. Power to the Data Acquisition System
10 is provided by a power supply 74 which may be an
internal battery or an external source of electrical
power may be provided. When the program line 58 is not
pulled low (ground potential) the CPU 56 is operated
under program control of the EEPROM 62. The program in
the EEPROM 62 may also make use of subprograms within the
I5 ROM 60 ~o conserve memory locations in the EEPROM 62 for
data storage.
Referring now to FIG. 2, a flow diagram of a program
for the data acquisition system 10 is shown. At the
start, the program monitors the interrogate line 70 and
if the line is not high the program will continue in a
short loop. This interrogate line could be tied to the
master switch of a vehicle in which the data acquisition
system 10 has been installed. In such a case the only
data of concern is that data occurring when the master
switch is on. If the interrogate line is high, the
program will cause the CPU 56 to read the analog to
digital converters 48, 50, 52 and 54. After the analog
to digital converters 48, 50, 52 and 54 are read, the
data is stored in the EEPROM 66.
While not indicated in FIG. 2, it will be
appreciated that the stored data could be compared to the
previous data to determine if this data is higher. If
the new data is higher it can be stored as the peak in
one location within the EEPROM and replaced with new data
when it exceeds this level. The time of the peak could
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1 also be stored. Also at this time, new data could be
averaged in with the previous data and the average
stored. The flow diagram in FI~. 2 shows that samples
are taken every 100 milliseconds. This time could be
changed to almost any value, for example, one every 100
microseconds, or one each year.
Referring now to FIG. 3, a flow diagram of the data
acquisition system 10 programmed to be used as a fire
sensor is shown. At the start of the program, the status
line 72 i~ pulled low (reset). This line is used as a
fire warning output signal line, which will go high in
case of a fire. After the status line 72 is reset
(turned off) the CPU 56 will check the signal level from
the first detector 14. If this signal is over
predetermined threshold then the CPU will check the
signal from the number two detector 16, and if this
signal is also over threshold the CPU 56 will cause the
status line to go high indicating a fire. From there the
CPU will branch back to test the signal levels from the
detectors again. As soon as one detector goes below its
threshold then the CPU will branch back to the start and
reset the status line 72.
It will be appreciated that the program in FIG. 3 is
for a very simple fire sensor which merely requires a
simultaneous signal of sufficient amplitude from two
detectors sensitive to different wavelengths. Much more
complex fire sensor programs could be used such as those
described in U.S. Patent Nos. 4,691,196; 4,639,598;
4,665,390; 4,679,156; 4,769,775; 4,647,776; 4,472,715;
and 4,469,944. It will be appreciated that performing
the more sophisticated signal processing as provided in
some of ~he above patents will require more circuitry
then delineated herein.
It is an important feature that the data acquisition
system 10 can be used both as a fire detector as
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1 described in connection with FIGS. 1 and 3 above and as a
data acquisition system 10 as described in connec~ion
with FIGS. 1 and 2 simultaneously. This may be
accomplished by programming the data acquisition system
10 to perform both the data storage functions, shown in
FIG. 2, as well as the fire detection functions shown in
FIG. 3. It may be useful to have the fire output latch
the memories 60, 62 and 64, so that the data stored
therein is not displaced after the fire. Thus, once a
fire is detected it will be possible to analyze the
status of the detectors for a period of time preceding
the fire. In this way a history of the events leading to
the fire will be recorded. For example, it may be useful
to know what changes took place preceding the fire in
detected parameters such as radiometric, photometric,
temperature, pressure, acceleration, etc. This
- information will be very useful for diagnosing cause of
the fire and will save a great deal of time in conducting
the post fire investigation.
From the foregoing it can be appreciated that the
present invention provides a Data Acquisition System 10
that is portable, occupies little space, can be used in
harsh environments and left for extended period of time
unattended without interfering with the equipment or
vehicle in which it is placed. A further advantage is
that no power is necessary for the Data Acquisition
System 10 to retain the recorded data due to the use of
the EEPROM 62, so that the Data Acquisition Sy~tem 10
could be disconnected from its site and ~ent to another
location for the downloading of data. Those skilled in
the art can appreciate that other advantages can be
obtained from the use of this invention and that
modification may be made without departing from the true
spirit of the invention after studying the specification,
drawings, and following claims.
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