CA1285636C - Optical collision avoidance system - Google Patents
Optical collision avoidance systemInfo
- Publication number
- CA1285636C CA1285636C CA000540185A CA540185A CA1285636C CA 1285636 C CA1285636 C CA 1285636C CA 000540185 A CA000540185 A CA 000540185A CA 540185 A CA540185 A CA 540185A CA 1285636 C CA1285636 C CA 1285636C
- Authority
- CA
- Canada
- Prior art keywords
- pulsed light
- light sources
- detection
- light source
- aircraft
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000003287 optical effect Effects 0.000 title claims 7
- 238000001514 detection method Methods 0.000 claims abstract description 26
- 230000000903 blocking effect Effects 0.000 claims description 6
- 230000003449 preventive effect Effects 0.000 claims 3
- 238000001429 visible spectrum Methods 0.000 claims 1
- 238000012545 processing Methods 0.000 abstract description 4
- 230000000007 visual effect Effects 0.000 abstract description 3
- 238000000034 method Methods 0.000 abstract description 2
- 240000007320 Pinus strobus Species 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000035945 sensitivity Effects 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000003455 independent Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Landscapes
- Traffic Control Systems (AREA)
- Geophysics And Detection Of Objects (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A proximity detecting and warning system for use in collision avoidance, particularly with aircraft. The system responds to pulsed light sources within a selected frequency band and particularly the frequency of aircraft strobe and rotating beacon light sources while disregarding any other natural steady state light sources as well as man-made light sources such as street lighting and ground lighting sources. The system detects pulsed light sources on aircraft or vehicles within the proximity pilot or operator. The alarm occurs when another aircraft is within the detection envelope which typically extends in an elliptical pattern around the transmitter in all directions with a detection range of up to approximately three miles. The circuit is designed to detect the strobe or rotating beacons having frequencies standardized by Federal Regulation which also requires that these sources be illuminated at all times during flight. The proximity sensing system has a light pulse detector, a circuit for limiting the response of the device to the particular frequencies selected, and processing circuits which process received signals to discriminate between the selected frequencies and activates the visual and audible alarms.
A proximity detecting and warning system for use in collision avoidance, particularly with aircraft. The system responds to pulsed light sources within a selected frequency band and particularly the frequency of aircraft strobe and rotating beacon light sources while disregarding any other natural steady state light sources as well as man-made light sources such as street lighting and ground lighting sources. The system detects pulsed light sources on aircraft or vehicles within the proximity pilot or operator. The alarm occurs when another aircraft is within the detection envelope which typically extends in an elliptical pattern around the transmitter in all directions with a detection range of up to approximately three miles. The circuit is designed to detect the strobe or rotating beacons having frequencies standardized by Federal Regulation which also requires that these sources be illuminated at all times during flight. The proximity sensing system has a light pulse detector, a circuit for limiting the response of the device to the particular frequencies selected, and processing circuits which process received signals to discriminate between the selected frequencies and activates the visual and audible alarms.
Description
Field of the Invention This invention is related to collision avoidance systems and is more particularly rela-ted to proximity detec-tion, warning and aircraft collision avoidance systems sensi-tive to pulsed light soufces.
Back~round of the Invention Collision avoidance systems presently in use are expensive, sophisticated, complex and often require interaction with other systems to be effective. Even the very sophistica-ted electronic systems available today have not been comple-tely successful in avoiding midair collisions of aircraft, particu-larly with small aircraft. Most midair accidents in recent history could have been avoided if there had been some device or system on board either aircraft to alert the pilot of the near proximity of the other aircraf-t. Sophisticated systems utilize radar or radio signals that can activate similarly equipped aircraEt. However, these devices are active in nature, meaning that they must transmit and receive certain signals in order to provide a warning. Thus, to be effective all aircraEt must be equipped with the same system for the :
overall system to function effectively. Further, o~ners of small aircraft cannot afford the thousands of dollars to install this equipment in a relatively inexpensive aircraft which may cost less ~than the collision avoidance system.
Taking into consideration both the high cost and the inconsis-tent reliability a different approach to aviation collision :
~;~ avoidance and proximity warning systems is needed.
It is therefore one object of the present invention to provide a proximity detection and warning system which is low in cost buk reliable.
::;
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~ , ' ' , ~ ' " ' ~ ' . ~ .
~2~51~
~2599-~47 ~ nother object of the present invention is to provide a proximity detection and warning system that operates indepen-dent of dedicated systems in other aircraft.
Still another object of the present invention is to provide a proximity detector and warning system which is sensi-tive to a characteristic nearly all aircraf-t have which will provide a warning when such an aircraft is within a predeter-mined distance.
Still another object of the presen-t invention is to provide a proximity detection and warning system which is sensitive to pulsed light sources within the envelope of the detection system.
Still another object of the present invention is -to provide a proximity warning and detection system tuned to the frequency of pulsed light emitted from an object while reject-ing all other sources of light.
Brief Description of the Invention The purpose of the presen-t invention is to provide a proximity detection and warning system which alerts an operator of an object with which it could potentially collide within the envelope of the detection system. Such a system can be useful for aircraft, ambulances, fire truck and police vehicles as well as private vehicles to enable an operator to detect the - presence of a vehicle or aircraft and take evasive action.
The proximity warning and detection system is comprised of a detec-tor sensi-tive to the pulsed light from strobe lights or flashing lights on vehicles or aircraft. The output o-f the detector is processed through a blocking circuit to block ambient, man-made or any other non-pulsing light.
Filter circuits limit the sensitivity oE the system to light .~ - 2 -~5~
~25g9-147 frequency selected. Frequency discrimination is provided by a band pass filter whose limits respond to liyht sour~es within the frequency of -the filter. Further processing in the detec-tion circuit determines whether the light pulse signals are the type of pulse from flashing lights and whether the signal is sufficient to trigger a warning alarm or indicator.
~ he light detector is selected to detect light in a preselected portion of the frequency spectrum and provide a signal processed b-y a coordinate convertor to determine the angle and relative distance -to -the detected target. The co-ordinate convertor is an X, Y coordinate convertor w'hich samples the detected pulse levels from several sensors and provides an output indicating the direction and relative distance.
One version of the system is sufficiently sensitive to be directed towards general aviation VFR (visual flight rules) aircraft application. A two to three mile range is suitable for that purpose. A less sensitive system could have a range of 1,000 to 1,500 feet which would be suitable ~or control of traffic signals by emergency vehicles. For example, am'~ulances, fire trucks and police vehicles with flashing strobes or beacons can automatically turn traffic signals red at the selected distance to stop non-emergency traffic. An even less sensitive system with a range of perhaps 500 feet could be useful in automobiles to enable a driver to detec-t the presence of emergency vehicles despite closed windows, air-conditioners and a blaring radio.
; The above and other features of the invention will be fully understood from the following detailed description and t'he accompanying drawings, in which:
.
~s~
Figure I is a block diagram of a pro~imity de-tection and warning system.
Figure 2 is a semi-schematic circuit diagram for the pro~imity detection and warning system for Figure 1.
Detailed Description of _he Invention A proximity detection and warning system is illustra-ted in the block diagram of Figure 1. A light pulse detector 10 is provided which is a specially selected photo transistor sensitive to a light band within a wide spec-trum which includes pulsed light sources. rrhat is it is selected for sensitivity in the .5 micron to 1.0 micron wavelength light region. To prevent light pulse detector 10 from responding -to pulsing strobes on the host vehicle blanking circuit 12 is provided which inhibits the light pulse detect photo transistor 10 -from operating when the host vehicle or aircraft's own lights are flashing. Each flash of the host's lights causes an output ~rom blanking circuit 12 which interrupts operation of light pulse detector 10.
When photo transistor or light pulse de-tector 10 deteats a light pulse in the wavelength it is sensitive to, it provides an output to DC blocking circuit 14. DC block circui-t 14 is comprised of a resistor and capacitor combination network which blocks transfer of all output -Erom phototransistor 10 not produced by pulsed light sources. ~hus DC block circuit 14 allows only pulsed light to pass to the subsequent processing circuitry. rrhe output of the DC block circuit is -then fed to a band pass filter 16 which strips away all fre~uency response not in the pass band of the fil-ter. rrhis effectively elimi-nates all pulsed light sources o-ther than those selected for detection.
5~ i5 ~2599-147 Protection against other unwanted pulse light sources is further provided by pulse width discriminator 18 which wilL
eliminate unwanted momen-tary light pulsed siynals such as lightning, sunlight, moonlight, random flashes, etc. Discrimi-nation circuit 18 further increases the sensitivity of the system to only the pulse light sources selected for detection.
Threshold de-tect circuit 20 ad]usts the processing circuit sensitivity to the range (i.e., distance) desired.
Detected signals which are not above a pre~set threshold of detector 20 will not trigger any warning. Thus the detection range can be selec-ted by appropria-te adjustment of threshold detect circuit 20. The more sensitive the circuit the greater the range. As indicated previously for aircraEt this may be up to three miles, while for land based private vehicles it may be as low as 500 feet. When a signal in the proper Erequency having the proper intensity to activate threshold detect circuit 20 is detected the output ac-tivates an audio warning device 22 which may be any type oE horn, bell or any suitable audio warning system.
The output from the threshold detector is also connected to X, Y coordinate convertor 24 which receives out-puts from one or more additional detect channels 26. The X, Y
coordinate convertor determines the angle and relative distance to the detected target by sampling and comparing the detected pulse levels from several sensors of the additional detector channels. The output of the X, Y coordinate convertor acti-vates a LED or LCD or other visual indicator display 28. The entire system can be operated by a power supply 30 which can be an on-board battery or power supply or from a separate power supply~
~ - 5 -In use on an aircraft several light pulse detectors and associa-ted circuitry can be positioned on the fuselage and wings of an aircraft to detect other approaching aircraft. On an aircraft at least two and preferably three to four of the detection devices and associated circuitry would be desirable.
The modest cost and relative simplicity of the circuitry will permit the use of several channels even on smal] aircraft.
For emergency and private land based vehicles a single detector would probably be sufficient as the range and direction information is not rea:lly as critical as with air-craft.
In the semi-schematic circuit diagram of Fig. 2 a circuit suitable for use in the proximity de-tection and warning system is shown. Part numbers are given by way of example for suitable components for use in -the system circuit.
Blan~sing circuit 12 is comprised of an RCA 3140 amplifier Al configured to provide a blanking pulse as shown at 13, synchronized to the strobe pulses of the host aircraft lights which inhibits a response to the host aircraft's own flashing lights. Pulse 13 inhibits operations o-E light pulse detectcr Ql which may be a FPT 100 phototransistor. DC block-ing and pulse width discrimination circuits 14, 18 are provided by transistor Q2 (2N2222) and its associated circuitry which - limits detection to only selected pulsed light sources. Band-~;~ pass filtering is provided by an RCA* 3130 amplifier A2 and its associated circuitry configured to strip away all frequencies not in the pass band of filter 16.
Preferably also included with the system is a control and test unit 15 (Figure 1). This unit contains all the con-trols and associated circuitry for built in operation and *Trade-mark .~
~'~
sys-tem checkout testiny.
Threshold detect and pulse coun-ting circuit 20 is comprised of an Intersil* 7208 integrated circuit (IC) 23 and Intersil* 7207A clock 21 as a master timer controlled by capacitors C, C2 and crystal ~C. The output of -threshold de-tect circuit is connected to an X-Y coordinate converter for display on a digital display. ~s shown in Figure 1 the X-Y
coordinate converter also receives inputs from other detec-t channels processes them and display the position of the approaching target or aircraft on digital display 28 which may be a common cathode LED display.
This invention is not to be limited by the embodiment showing the drawings and described in the description which is given by way of example and not of limitation but only in accordance with the scope o~ the appended claims.
.
.
:; :
*Trade-mark - 6a -~:
~,
Back~round of the Invention Collision avoidance systems presently in use are expensive, sophisticated, complex and often require interaction with other systems to be effective. Even the very sophistica-ted electronic systems available today have not been comple-tely successful in avoiding midair collisions of aircraft, particu-larly with small aircraft. Most midair accidents in recent history could have been avoided if there had been some device or system on board either aircraft to alert the pilot of the near proximity of the other aircraf-t. Sophisticated systems utilize radar or radio signals that can activate similarly equipped aircraEt. However, these devices are active in nature, meaning that they must transmit and receive certain signals in order to provide a warning. Thus, to be effective all aircraEt must be equipped with the same system for the :
overall system to function effectively. Further, o~ners of small aircraft cannot afford the thousands of dollars to install this equipment in a relatively inexpensive aircraft which may cost less ~than the collision avoidance system.
Taking into consideration both the high cost and the inconsis-tent reliability a different approach to aviation collision :
~;~ avoidance and proximity warning systems is needed.
It is therefore one object of the present invention to provide a proximity detection and warning system which is low in cost buk reliable.
::;
:: ~
~ , ' ' , ~ ' " ' ~ ' . ~ .
~2~51~
~2599-~47 ~ nother object of the present invention is to provide a proximity detection and warning system that operates indepen-dent of dedicated systems in other aircraft.
Still another object of the present invention is to provide a proximity detector and warning system which is sensi-tive to a characteristic nearly all aircraf-t have which will provide a warning when such an aircraft is within a predeter-mined distance.
Still another object of the presen-t invention is to provide a proximity detection and warning system which is sensitive to pulsed light sources within the envelope of the detection system.
Still another object of the present invention is -to provide a proximity warning and detection system tuned to the frequency of pulsed light emitted from an object while reject-ing all other sources of light.
Brief Description of the Invention The purpose of the presen-t invention is to provide a proximity detection and warning system which alerts an operator of an object with which it could potentially collide within the envelope of the detection system. Such a system can be useful for aircraft, ambulances, fire truck and police vehicles as well as private vehicles to enable an operator to detect the - presence of a vehicle or aircraft and take evasive action.
The proximity warning and detection system is comprised of a detec-tor sensi-tive to the pulsed light from strobe lights or flashing lights on vehicles or aircraft. The output o-f the detector is processed through a blocking circuit to block ambient, man-made or any other non-pulsing light.
Filter circuits limit the sensitivity oE the system to light .~ - 2 -~5~
~25g9-147 frequency selected. Frequency discrimination is provided by a band pass filter whose limits respond to liyht sour~es within the frequency of -the filter. Further processing in the detec-tion circuit determines whether the light pulse signals are the type of pulse from flashing lights and whether the signal is sufficient to trigger a warning alarm or indicator.
~ he light detector is selected to detect light in a preselected portion of the frequency spectrum and provide a signal processed b-y a coordinate convertor to determine the angle and relative distance -to -the detected target. The co-ordinate convertor is an X, Y coordinate convertor w'hich samples the detected pulse levels from several sensors and provides an output indicating the direction and relative distance.
One version of the system is sufficiently sensitive to be directed towards general aviation VFR (visual flight rules) aircraft application. A two to three mile range is suitable for that purpose. A less sensitive system could have a range of 1,000 to 1,500 feet which would be suitable ~or control of traffic signals by emergency vehicles. For example, am'~ulances, fire trucks and police vehicles with flashing strobes or beacons can automatically turn traffic signals red at the selected distance to stop non-emergency traffic. An even less sensitive system with a range of perhaps 500 feet could be useful in automobiles to enable a driver to detec-t the presence of emergency vehicles despite closed windows, air-conditioners and a blaring radio.
; The above and other features of the invention will be fully understood from the following detailed description and t'he accompanying drawings, in which:
.
~s~
Figure I is a block diagram of a pro~imity de-tection and warning system.
Figure 2 is a semi-schematic circuit diagram for the pro~imity detection and warning system for Figure 1.
Detailed Description of _he Invention A proximity detection and warning system is illustra-ted in the block diagram of Figure 1. A light pulse detector 10 is provided which is a specially selected photo transistor sensitive to a light band within a wide spec-trum which includes pulsed light sources. rrhat is it is selected for sensitivity in the .5 micron to 1.0 micron wavelength light region. To prevent light pulse detector 10 from responding -to pulsing strobes on the host vehicle blanking circuit 12 is provided which inhibits the light pulse detect photo transistor 10 -from operating when the host vehicle or aircraft's own lights are flashing. Each flash of the host's lights causes an output ~rom blanking circuit 12 which interrupts operation of light pulse detector 10.
When photo transistor or light pulse de-tector 10 deteats a light pulse in the wavelength it is sensitive to, it provides an output to DC blocking circuit 14. DC block circui-t 14 is comprised of a resistor and capacitor combination network which blocks transfer of all output -Erom phototransistor 10 not produced by pulsed light sources. ~hus DC block circuit 14 allows only pulsed light to pass to the subsequent processing circuitry. rrhe output of the DC block circuit is -then fed to a band pass filter 16 which strips away all fre~uency response not in the pass band of the fil-ter. rrhis effectively elimi-nates all pulsed light sources o-ther than those selected for detection.
5~ i5 ~2599-147 Protection against other unwanted pulse light sources is further provided by pulse width discriminator 18 which wilL
eliminate unwanted momen-tary light pulsed siynals such as lightning, sunlight, moonlight, random flashes, etc. Discrimi-nation circuit 18 further increases the sensitivity of the system to only the pulse light sources selected for detection.
Threshold de-tect circuit 20 ad]usts the processing circuit sensitivity to the range (i.e., distance) desired.
Detected signals which are not above a pre~set threshold of detector 20 will not trigger any warning. Thus the detection range can be selec-ted by appropria-te adjustment of threshold detect circuit 20. The more sensitive the circuit the greater the range. As indicated previously for aircraEt this may be up to three miles, while for land based private vehicles it may be as low as 500 feet. When a signal in the proper Erequency having the proper intensity to activate threshold detect circuit 20 is detected the output ac-tivates an audio warning device 22 which may be any type oE horn, bell or any suitable audio warning system.
The output from the threshold detector is also connected to X, Y coordinate convertor 24 which receives out-puts from one or more additional detect channels 26. The X, Y
coordinate convertor determines the angle and relative distance to the detected target by sampling and comparing the detected pulse levels from several sensors of the additional detector channels. The output of the X, Y coordinate convertor acti-vates a LED or LCD or other visual indicator display 28. The entire system can be operated by a power supply 30 which can be an on-board battery or power supply or from a separate power supply~
~ - 5 -In use on an aircraft several light pulse detectors and associa-ted circuitry can be positioned on the fuselage and wings of an aircraft to detect other approaching aircraft. On an aircraft at least two and preferably three to four of the detection devices and associated circuitry would be desirable.
The modest cost and relative simplicity of the circuitry will permit the use of several channels even on smal] aircraft.
For emergency and private land based vehicles a single detector would probably be sufficient as the range and direction information is not rea:lly as critical as with air-craft.
In the semi-schematic circuit diagram of Fig. 2 a circuit suitable for use in the proximity de-tection and warning system is shown. Part numbers are given by way of example for suitable components for use in -the system circuit.
Blan~sing circuit 12 is comprised of an RCA 3140 amplifier Al configured to provide a blanking pulse as shown at 13, synchronized to the strobe pulses of the host aircraft lights which inhibits a response to the host aircraft's own flashing lights. Pulse 13 inhibits operations o-E light pulse detectcr Ql which may be a FPT 100 phototransistor. DC block-ing and pulse width discrimination circuits 14, 18 are provided by transistor Q2 (2N2222) and its associated circuitry which - limits detection to only selected pulsed light sources. Band-~;~ pass filtering is provided by an RCA* 3130 amplifier A2 and its associated circuitry configured to strip away all frequencies not in the pass band of filter 16.
Preferably also included with the system is a control and test unit 15 (Figure 1). This unit contains all the con-trols and associated circuitry for built in operation and *Trade-mark .~
~'~
sys-tem checkout testiny.
Threshold detect and pulse coun-ting circuit 20 is comprised of an Intersil* 7208 integrated circuit (IC) 23 and Intersil* 7207A clock 21 as a master timer controlled by capacitors C, C2 and crystal ~C. The output of -threshold de-tect circuit is connected to an X-Y coordinate converter for display on a digital display. ~s shown in Figure 1 the X-Y
coordinate converter also receives inputs from other detec-t channels processes them and display the position of the approaching target or aircraft on digital display 28 which may be a common cathode LED display.
This invention is not to be limited by the embodiment showing the drawings and described in the description which is given by way of example and not of limitation but only in accordance with the scope o~ the appended claims.
.
.
:; :
*Trade-mark - 6a -~:
~,
Claims (10)
1. An optical proximity system mounted on a first body comprising:
optical detecting means responsive to a pulsed light source in the visible and near visible range mounted on a second body detection preventive means preventing detection of unwanted light sources; said detection preventive means preventing detection of all light from sources other than a prescribed pulsed light source on a second body distance determining means for determining the relative distance of a detected pulsed light source;
direction determining means determining the relative direction of a detected pulsed light source;
indicating means indicating the relative direction of said detected pulsed light source; and alarm indicating means indicating the detection of a prescribed pulsed light source within a distance determined by said distance determining means.
optical detecting means responsive to a pulsed light source in the visible and near visible range mounted on a second body detection preventive means preventing detection of unwanted light sources; said detection preventive means preventing detection of all light from sources other than a prescribed pulsed light source on a second body distance determining means for determining the relative distance of a detected pulsed light source;
direction determining means determining the relative direction of a detected pulsed light source;
indicating means indicating the relative direction of said detected pulsed light source; and alarm indicating means indicating the detection of a prescribed pulsed light source within a distance determined by said distance determining means.
2. The system according to claim 1 in which said detection preventive means includes:
blocking means connected to said optical detecting means for blocking steady state light sources.
blocking means connected to said optical detecting means for blocking steady state light sources.
3. The system according to claim 2 in which said discriminating means includes band pass filter means receiving the output of said blocking means; said band pass filter means rejecting all pulsed light sources outside the pass band of said filter means.
4. The system according to claim 3 in which said discriminating means includes pulse width discriminating means for rejecting unwanted momentary pulsed light signals.
5. The system according to claim 1 in which said distance determining means includes light amplitude detecting means for detecting whether the amplitude of said detected pulsed light source is sufficient to trigger said alarm indicator.
6. The system according to claim 5 in which said amplitude detector comprises a threshold detector.
7. The system according to claim 1 in which said direction determining means includes location detection means for detecting the location of said selected pulsed light source.
8. The system according to claim 7 in which said location detector means comprises:
a plurality of said optical detecting sources;
coordinate converting means for comparing and converting the output of said plurality of optical detecting means;
display-means receiving and displaying the output of said coordinate converting means.
a plurality of said optical detecting sources;
coordinate converting means for comparing and converting the output of said plurality of optical detecting means;
display-means receiving and displaying the output of said coordinate converting means.
9. The system according to claim 1 in which said optical detecting means includes a photo-transistor sensitive to light sources in the visible spectrum.
10. The system according to claim 9 in which said photo-transistor is sensitive to frequencies in the range of 0.5 to 1.0 microns.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000540185A CA1285636C (en) | 1987-06-19 | 1987-06-19 | Optical collision avoidance system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000540185A CA1285636C (en) | 1987-06-19 | 1987-06-19 | Optical collision avoidance system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1285636C true CA1285636C (en) | 1991-07-02 |
Family
ID=4135949
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000540185A Expired - Lifetime CA1285636C (en) | 1987-06-19 | 1987-06-19 | Optical collision avoidance system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1285636C (en) |
-
1987
- 1987-06-19 CA CA000540185A patent/CA1285636C/en not_active Expired - Lifetime
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| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |