CA1197916A - Motion detector signal processing circuit - Google Patents
Motion detector signal processing circuitInfo
- Publication number
- CA1197916A CA1197916A CA000397995A CA397995A CA1197916A CA 1197916 A CA1197916 A CA 1197916A CA 000397995 A CA000397995 A CA 000397995A CA 397995 A CA397995 A CA 397995A CA 1197916 A CA1197916 A CA 1197916A
- Authority
- CA
- Canada
- Prior art keywords
- circuit
- alarm
- motion detector
- accumulator
- gate
- 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
Links
Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/22—Electrical actuation
- G08B13/24—Electrical actuation by interference with electromagnetic field distribution
- G08B13/2491—Intrusion detection systems, i.e. where the body of an intruder causes the interference with the electromagnetic field
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
- G01S15/50—Systems of measurement, based on relative movement of the target
- G01S15/52—Discriminating between fixed and moving objects or between objects moving at different speeds
- G01S15/523—Discriminating between fixed and moving objects or between objects moving at different speeds for presence detection
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/16—Actuation by interference with mechanical vibrations in air or other fluid
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Acoustics & Sound (AREA)
- Computer Networks & Wireless Communication (AREA)
- Burglar Alarm Systems (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A motion detector circuit comprising a trans-mitter for transmitting a detection signal field in an area to be protected. A receiver is provided for sensing the signal field. A signal squaring circuit is connected to the receiver for producing control pulses in response to AC signals caused by movement of an object in said field. A square wave generator produces alarm pulses corresponding to the control pulses. An interval timer circuit and an accumulator circuit is connected to an output of the generator. The interval timer circuit enables the accumulator for a predetermined time interval starting from the presence of a first alarm pulse at the output of the generator. The accumu-lator is connected to an alarm which is activated by operation of the accumulator when a preset threshold value is exceeded within the predetermined time interval that is enable by the timer circuit.
A motion detector circuit comprising a trans-mitter for transmitting a detection signal field in an area to be protected. A receiver is provided for sensing the signal field. A signal squaring circuit is connected to the receiver for producing control pulses in response to AC signals caused by movement of an object in said field. A square wave generator produces alarm pulses corresponding to the control pulses. An interval timer circuit and an accumulator circuit is connected to an output of the generator. The interval timer circuit enables the accumulator for a predetermined time interval starting from the presence of a first alarm pulse at the output of the generator. The accumu-lator is connected to an alarm which is activated by operation of the accumulator when a preset threshold value is exceeded within the predetermined time interval that is enable by the timer circuit.
Description
BACKGROUND_OF_INVENTION:
a. Field of the Invention The present invention relates to a motion ~ detector circuit for use in security applications to detect the presence of intruders into any portion of a protected area.
b. Description of Prior Art Various types of motion detectors are known.
The problem ~ith known motion detectors is that they produce a great deal of false alarms and are very difficult to install and calibrate. The occurrence of false alarms is so great that certain communities impose fines if a user of the alarm has more than one false alarm per month.
~
It is therefore a feature of the present invention to provide a motion detector circuit for security applications ar-d incorporating novel circuitry whereby to greatly reduce false alarms and substantially eliminate same.
Another feature of the present invention is to provide a motion detector circuit having features permitting easy installation and calibration.
According to the above features, from a broad aspect, the present invention provides a motion detector circuit comprising a transmitter for transmitting a detection signal field in an area to be protected. A
receiver is provided for sensing the signal field. A
signal squaring circuit is connected to the receiver for producing control pulses in response to disturbance signals
a. Field of the Invention The present invention relates to a motion ~ detector circuit for use in security applications to detect the presence of intruders into any portion of a protected area.
b. Description of Prior Art Various types of motion detectors are known.
The problem ~ith known motion detectors is that they produce a great deal of false alarms and are very difficult to install and calibrate. The occurrence of false alarms is so great that certain communities impose fines if a user of the alarm has more than one false alarm per month.
~
It is therefore a feature of the present invention to provide a motion detector circuit for security applications ar-d incorporating novel circuitry whereby to greatly reduce false alarms and substantially eliminate same.
Another feature of the present invention is to provide a motion detector circuit having features permitting easy installation and calibration.
According to the above features, from a broad aspect, the present invention provides a motion detector circuit comprising a transmitter for transmitting a detection signal field in an area to be protected. A
receiver is provided for sensing the signal field. A
signal squaring circuit is connected to the receiver for producing control pulses in response to disturbance signals
- 2 - ~
caused by movement of an object in said field. A square wave generator produces alarm pulses corresponding to the control pulses. An interval timer circuit and an accumulator circuit is connected to an output of the generator. The interval timer circuit enables the accumulator for a predetermined time interval starting from the presence of a first alarm pulse at the output of the generator. The accumulator is connected to an alarrn which is activated by operation of the accumulator when a preset threshold value is exceeded within the predetermined time interval that is enabled by the timer circuit.
BRIE~ DESCRIPTION OF DRAWINGS:
A preferred embodiment of the present inven-tion will now be described with reference to the drawing which is a schematic representation of the motion detector circuit of the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS:
Referring now to the drawing, the motion detector circuit 10 is comprised of the following basic circuits. A power supply 11 provides the basic voltages to various component parts of the system and is of a standard design and no claim of originality is made herein and accordingly its construction will not be described. Similarly, a transmitter 12 is provided to generate a detection signal field in an area to be protected. The transmitter may be of the type producing an electromagnetic wave or, as shown in the drawing, is comprised of an ultrasonic sound generator for transmit-ting a detection field at a doppler frequency resulting rate.
The receiver 13 is herein shown as an ultrasonic receiver having a transceiver input 1~ for detecting any disturbances in the transmitted field, amplifier stages 15 and a phase detection circuit 16. This circuit is also of a conventional design and the details thereof will not be described herein.
A signal squaring circuit 17 is connected to the output of the receiver 13 and is provided to produce control pulses in response to disturbance signals (AC
signals) generated on the output of the receiver and caused by movement of an object in the transmitted field.
A square wave generator 18 is coupled to the squaring circuit 17 through a low pass filter and gate circuit 19.
The square wave generator 18 produces alarm pulses corresponding to ~he control pulses applied at its input.
An interval timer circuit 20 and an accumulator circuit 21 are connected respectively to an output 22 of the square wave generator. The interval timer circuit 20 enables the accumulator 21 for a predetermined time interval starting from the presence of a first alarm pulse at the output of the generator 22. The accumulator 21 is connected to an alarm control circuit 23 which is activated by operation of the accumulator when a preset threshold value is exceeded within the predetermined time interval that is enabled by the timer circuit. A pulse display circuit 2~ is also connected to the output 22 and it will be described in more detail later.
The signal squaring circuit 17 is comprised essentially of two gates, gate 25 and gate 26. Resistance 27 is connected to the power supply and provides a voltage gL~!g7~:~6 to the input of gate 26. When first energized, the output 28 of gate 26 will tend to go low. At the same time resistance 29 will pull the gate input voltage below the threshold of the gate, tending to switch the output high again~ This oscillation is smoothed out by the capacitor 30. As a result of the construction of the circuit, the voltage at the input of gate 26 is at a level which is equal to the threshold voltage of the gate.
Resistances 31 and 32 provide a voltage divider to set the bias of the second gate 25 below its threshold value. Therefore, any doppler signal of significant amplitude caused by disturbances in the field and obtained on the output of the receiver 13 and coupled to the gate 25 through capacitance 33 and the low pass filter formed by resistance 34 and capacitor 35 will trigger the gate 25 and produce at its output square pulses. These pulses are herein defined as controlled pulses which are respon-sive to disturbance signals caused by the movement of an object in the transmitted field.
When a doppler signal is applied to the input of gate 25 9 the resulting relative width of the output pulse of gate 25 is proportional to the doppler signal's amplitude. The narrower the pulse, the higher its harmonic content compared to the doppler signal's fundamental. As a result, the frequency response at the lower end of the overall band pass is proportional to the doppler signal amplitude. For the ultrasonic detector, described herein, typical response for the lower frequency in function of amplitude at input A are:
979~;
6 to 8 M. ~olts ........... Band pass starting at 65 Hertz.
50 to 100 M. Volts...... ~.Band pass starting at 18 Hertz.
The benefit of the above, in the ultrasonic motion detector, is a substantial decrease in susceptibility to air turbulence. Air turbulence usually produces doppler signals of lower amplitude and lower frequency than human movement. With this processing9 a sharp filtering of the upper end of the band pass is possible, inexpensively (Not a function of amplitude).
The control pulses at the output of the signal squaring circuit 17 are filtered again by the low pass filter network constituted by resistance 36, capacitance 37 and control rectifier 38 and these control pulses are applied to the input of a gate 39. This gate controls the functioning of the square wave generator 18.
The square wave generator 18 is comprised of two gates 40 and 41 and associated resistance 42 and capacitor 43~ The continued action of an average DC
component at the output of the gate 39, when pulsing, and the voltage drop across resistor 44 will bring 5a-9~;
the input of gate 40 above its threshold value allowing the generator to produce square waves of 2 to 4 Hertz per second. When there is no signal at the output of the gate 39 the pulse generator is blocked as the voltage drop between resistors 44 and 45 brings the input of gate - 40 below its threshold value.
As previously mentioned the output 22 of the generator 18 is connected to a reset interval timer 20 and an accumulator circuit 21. Under normal conditions, the reset interval timer 20 is inactive. That means that the input of gate 46 is low and the output of the gate is high. Therefore, the input of the other gate 47 is also high and it is coupled to the output of gate 46 through a control rectifier 48 and resistance ~9. The output of gate 47 is in a low state.
The accumulator 21 also is comprised of a gate 50 and its input is also low through the coupling via control rectifier 51. When the generator generates an output pulse, herein referred to as an alarm pulse, this signal is connected to the input of gate 46 via control rectifier S2 and resistance 63. Therefore, the output of gate 46 becomes low and the input of gate 47 is also low. A positive voltage is therefore produced at the output of gate 47 and it is fed to a charging circuit constituted by capacitor 54 which charges through control rectifier 55 and resistance 56. This charging takes place in a delay of approximately 25 seconds and at which time the charge on the capacitor is such that the input of gate 46 is lower than the threshold thereby causing the output of gate 47 to again reset to zero thereby discharging capacitor 54 through control recti-fier 57.
~1979~L E;
It is also noted that the output of the square wave generator 18 is connected to the accumulator 21 and the alarm pulse starts charging the capacitor 58 which forms part of an adjustable charging circuit in combination with variable resistance 59. The number of pulses necessary to change the state of gate 50 will be dependent on the adjustment of variable resistance 59.
The charge of capacitor 58 results from a number of these alarm pulses and the num~er of these pulses required to trigger the gate will depend on the adjustment of the resistance 59. If there are not enough pulses to charge the capacitor 58 within the predetermined time interval which is set by the charging of capacitor 54 , then capacitor 58 will discharge as capacitor 54 discharges.
The discharge path for capacitor 58 is through resis-tance 60 and control rectifier 51.
Under normal conditions, with the state of the gate 50 unchanged by the charging circuit, the output of the gate 50 is high (positive) keeping transistor 61 of the alarm control circuit 23 conducting and the relay 62 energized. When the output of the gate 50 is low (negative), transistor 61 opens and places the relay 62 in an alarm condition. The positive voltage present at the collector 63 of transistor 61 forces, through resistor 64, the gate 47 to close and discharge capacitor 54. Capacitor 65 of the alarm control circuit 23 in conjunction with resistance 66 will keep the alarm condition for approxi-mately 3 seconds. The collector 63 of transistor 61 is also applied to transistor 67 of the pulse display circuit through control rectifier 68 whereby to provide an alarm indication of the same amount of time.
~9t7~
The pulse display circuit is provided with a light emitting diode 69 to provide visual display of an alarm and also to display the occurrence of alarm pulses at the output 22 of the generator 18. These alarm pulses are connected to the transistor 67 through control rectifier 70. Control recti~ier diode 71 and resistance 72 are provided for the connection of an audible alarm device. The purpose of the light emitting diode 69 is to provide a display each time an alarm pulse is generated by the generator. This greatly facilitates the installation of the motion detector device and helps detect the range of the field generated thereby. This way, the installer knows what is happening before the alarm point is reached. The range of the unit can then be determined with accuracy and any non-human movements which might cause false alarms can be identified and remedial action taken.
It can be seen that with the combination of the reset interval timer and accumulator circuit that any false movement within the field will not cause an alarm as the gate 50 will not be triggered due to a non-repetitive generation of alarm pulses whereby ~fter a delay of approximately 25 seconds, the capacitors 54 and 58 will dischar~e without the triggering of an alarm.
When the alarm pulses are repetitive the capacitance 58 will charge to the threshold value of the gate 50 thereby triggering an alarm.
It is within the ambit of the present inventlon to cover any obvious modifications of the example of the preferred embodiment described herein provided such modifications fall within the scope of the appended claims.
It is also foreseen that the circuit can be connected to various other types of alarm devices such as fire alarms whereby to produce alarm pulses at the output of a generator similarly trigger the circuit. ~he fire detecting devices would have to produce continuous output signals whereby to trigger the alarm and any ; unsustained signals would not cause the alarm to be triggered, such as is the case when smoke detectors are activated by smoke from ~igarettes or burned toast.
caused by movement of an object in said field. A square wave generator produces alarm pulses corresponding to the control pulses. An interval timer circuit and an accumulator circuit is connected to an output of the generator. The interval timer circuit enables the accumulator for a predetermined time interval starting from the presence of a first alarm pulse at the output of the generator. The accumulator is connected to an alarrn which is activated by operation of the accumulator when a preset threshold value is exceeded within the predetermined time interval that is enabled by the timer circuit.
BRIE~ DESCRIPTION OF DRAWINGS:
A preferred embodiment of the present inven-tion will now be described with reference to the drawing which is a schematic representation of the motion detector circuit of the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS:
Referring now to the drawing, the motion detector circuit 10 is comprised of the following basic circuits. A power supply 11 provides the basic voltages to various component parts of the system and is of a standard design and no claim of originality is made herein and accordingly its construction will not be described. Similarly, a transmitter 12 is provided to generate a detection signal field in an area to be protected. The transmitter may be of the type producing an electromagnetic wave or, as shown in the drawing, is comprised of an ultrasonic sound generator for transmit-ting a detection field at a doppler frequency resulting rate.
The receiver 13 is herein shown as an ultrasonic receiver having a transceiver input 1~ for detecting any disturbances in the transmitted field, amplifier stages 15 and a phase detection circuit 16. This circuit is also of a conventional design and the details thereof will not be described herein.
A signal squaring circuit 17 is connected to the output of the receiver 13 and is provided to produce control pulses in response to disturbance signals (AC
signals) generated on the output of the receiver and caused by movement of an object in the transmitted field.
A square wave generator 18 is coupled to the squaring circuit 17 through a low pass filter and gate circuit 19.
The square wave generator 18 produces alarm pulses corresponding to ~he control pulses applied at its input.
An interval timer circuit 20 and an accumulator circuit 21 are connected respectively to an output 22 of the square wave generator. The interval timer circuit 20 enables the accumulator 21 for a predetermined time interval starting from the presence of a first alarm pulse at the output of the generator 22. The accumulator 21 is connected to an alarm control circuit 23 which is activated by operation of the accumulator when a preset threshold value is exceeded within the predetermined time interval that is enabled by the timer circuit. A pulse display circuit 2~ is also connected to the output 22 and it will be described in more detail later.
The signal squaring circuit 17 is comprised essentially of two gates, gate 25 and gate 26. Resistance 27 is connected to the power supply and provides a voltage gL~!g7~:~6 to the input of gate 26. When first energized, the output 28 of gate 26 will tend to go low. At the same time resistance 29 will pull the gate input voltage below the threshold of the gate, tending to switch the output high again~ This oscillation is smoothed out by the capacitor 30. As a result of the construction of the circuit, the voltage at the input of gate 26 is at a level which is equal to the threshold voltage of the gate.
Resistances 31 and 32 provide a voltage divider to set the bias of the second gate 25 below its threshold value. Therefore, any doppler signal of significant amplitude caused by disturbances in the field and obtained on the output of the receiver 13 and coupled to the gate 25 through capacitance 33 and the low pass filter formed by resistance 34 and capacitor 35 will trigger the gate 25 and produce at its output square pulses. These pulses are herein defined as controlled pulses which are respon-sive to disturbance signals caused by the movement of an object in the transmitted field.
When a doppler signal is applied to the input of gate 25 9 the resulting relative width of the output pulse of gate 25 is proportional to the doppler signal's amplitude. The narrower the pulse, the higher its harmonic content compared to the doppler signal's fundamental. As a result, the frequency response at the lower end of the overall band pass is proportional to the doppler signal amplitude. For the ultrasonic detector, described herein, typical response for the lower frequency in function of amplitude at input A are:
979~;
6 to 8 M. ~olts ........... Band pass starting at 65 Hertz.
50 to 100 M. Volts...... ~.Band pass starting at 18 Hertz.
The benefit of the above, in the ultrasonic motion detector, is a substantial decrease in susceptibility to air turbulence. Air turbulence usually produces doppler signals of lower amplitude and lower frequency than human movement. With this processing9 a sharp filtering of the upper end of the band pass is possible, inexpensively (Not a function of amplitude).
The control pulses at the output of the signal squaring circuit 17 are filtered again by the low pass filter network constituted by resistance 36, capacitance 37 and control rectifier 38 and these control pulses are applied to the input of a gate 39. This gate controls the functioning of the square wave generator 18.
The square wave generator 18 is comprised of two gates 40 and 41 and associated resistance 42 and capacitor 43~ The continued action of an average DC
component at the output of the gate 39, when pulsing, and the voltage drop across resistor 44 will bring 5a-9~;
the input of gate 40 above its threshold value allowing the generator to produce square waves of 2 to 4 Hertz per second. When there is no signal at the output of the gate 39 the pulse generator is blocked as the voltage drop between resistors 44 and 45 brings the input of gate - 40 below its threshold value.
As previously mentioned the output 22 of the generator 18 is connected to a reset interval timer 20 and an accumulator circuit 21. Under normal conditions, the reset interval timer 20 is inactive. That means that the input of gate 46 is low and the output of the gate is high. Therefore, the input of the other gate 47 is also high and it is coupled to the output of gate 46 through a control rectifier 48 and resistance ~9. The output of gate 47 is in a low state.
The accumulator 21 also is comprised of a gate 50 and its input is also low through the coupling via control rectifier 51. When the generator generates an output pulse, herein referred to as an alarm pulse, this signal is connected to the input of gate 46 via control rectifier S2 and resistance 63. Therefore, the output of gate 46 becomes low and the input of gate 47 is also low. A positive voltage is therefore produced at the output of gate 47 and it is fed to a charging circuit constituted by capacitor 54 which charges through control rectifier 55 and resistance 56. This charging takes place in a delay of approximately 25 seconds and at which time the charge on the capacitor is such that the input of gate 46 is lower than the threshold thereby causing the output of gate 47 to again reset to zero thereby discharging capacitor 54 through control recti-fier 57.
~1979~L E;
It is also noted that the output of the square wave generator 18 is connected to the accumulator 21 and the alarm pulse starts charging the capacitor 58 which forms part of an adjustable charging circuit in combination with variable resistance 59. The number of pulses necessary to change the state of gate 50 will be dependent on the adjustment of variable resistance 59.
The charge of capacitor 58 results from a number of these alarm pulses and the num~er of these pulses required to trigger the gate will depend on the adjustment of the resistance 59. If there are not enough pulses to charge the capacitor 58 within the predetermined time interval which is set by the charging of capacitor 54 , then capacitor 58 will discharge as capacitor 54 discharges.
The discharge path for capacitor 58 is through resis-tance 60 and control rectifier 51.
Under normal conditions, with the state of the gate 50 unchanged by the charging circuit, the output of the gate 50 is high (positive) keeping transistor 61 of the alarm control circuit 23 conducting and the relay 62 energized. When the output of the gate 50 is low (negative), transistor 61 opens and places the relay 62 in an alarm condition. The positive voltage present at the collector 63 of transistor 61 forces, through resistor 64, the gate 47 to close and discharge capacitor 54. Capacitor 65 of the alarm control circuit 23 in conjunction with resistance 66 will keep the alarm condition for approxi-mately 3 seconds. The collector 63 of transistor 61 is also applied to transistor 67 of the pulse display circuit through control rectifier 68 whereby to provide an alarm indication of the same amount of time.
~9t7~
The pulse display circuit is provided with a light emitting diode 69 to provide visual display of an alarm and also to display the occurrence of alarm pulses at the output 22 of the generator 18. These alarm pulses are connected to the transistor 67 through control rectifier 70. Control recti~ier diode 71 and resistance 72 are provided for the connection of an audible alarm device. The purpose of the light emitting diode 69 is to provide a display each time an alarm pulse is generated by the generator. This greatly facilitates the installation of the motion detector device and helps detect the range of the field generated thereby. This way, the installer knows what is happening before the alarm point is reached. The range of the unit can then be determined with accuracy and any non-human movements which might cause false alarms can be identified and remedial action taken.
It can be seen that with the combination of the reset interval timer and accumulator circuit that any false movement within the field will not cause an alarm as the gate 50 will not be triggered due to a non-repetitive generation of alarm pulses whereby ~fter a delay of approximately 25 seconds, the capacitors 54 and 58 will dischar~e without the triggering of an alarm.
When the alarm pulses are repetitive the capacitance 58 will charge to the threshold value of the gate 50 thereby triggering an alarm.
It is within the ambit of the present inventlon to cover any obvious modifications of the example of the preferred embodiment described herein provided such modifications fall within the scope of the appended claims.
It is also foreseen that the circuit can be connected to various other types of alarm devices such as fire alarms whereby to produce alarm pulses at the output of a generator similarly trigger the circuit. ~he fire detecting devices would have to produce continuous output signals whereby to trigger the alarm and any ; unsustained signals would not cause the alarm to be triggered, such as is the case when smoke detectors are activated by smoke from ~igarettes or burned toast.
Claims (12)
1. A motion detector circuit comprising a transmitter for transmitting a detection signal field in an area to be protected, a receiver for sensing said signal field, a signal squaring circuit connected to said receiver for producing control pulses in response to disturbance signals caused by movement of an object in said field, a square wave generator for producing alarm pulses corresponding to said control pulses, an interval timer circuit and an accumulator connected to an output of said generator, said interval timer circuit enabling said accumulator for a predetermined time interval starting from the presence of a first alarm pulse at said output of said generator, said accumulator being connected to alarm means which is activated by operation of said accumulator when a preset threshold value is exceeded within said predetermined time interval that is enabled by said timer circuit.
2. A motion detector as claimed in claim 1 wherein said accumulator comprises a gate having an adjustable input charging circuit provided with adjustable means to adjust the operational threshold value of said gate.
3. A motion detector as claimed in claim 2 wherein said internal timer circuit is provided with a charging circuit having a predetermined charging time during which it enables said accumulator to permit said alarm pulses to charge said charging circuit of said accumulator.
4. A motion detector as claimed in claim 3 wherein said charging circuit comprises a charge accumulating capacitor connected in series with a variable resistance, said variable resistance constituting said adjustable means, and a discharge path for said charge accumulating capacitor.
5. A motion detector as claimed in claim 4 wherein said charging circuit of said interval timer circuit comprises a timing capacitor connected to said generator output and being charged for said predetermined period of time by said alarm pulses, and a gate circuit connected to said capacitor to discharge said timing capacitor and said charge accumulating capacitor to discharge.
6. A motion detector as claimed in claim 4 wherein said alarm means is connected to the output of said gate of said accumulator, said alarm means having a control circuit which is connected to said interval timer to discharge said charge accumulating capacitor to reset said gate and maintain an alarm condition for a set time interval.
7. A motion detector as claimed in claim 6 wherein said control circuit is also connected to a pulse display circuit to provide an alarm indication for the same amount of time as said set time interval.
8. A motion detector as claimed in claim 5 wherein said signal squaring circuit is a gate circuit having a voltage bias below its switching threshold so that small AC signals caused by movement in said field can produce a full voltage swing which are transformed into said control pulses.
9. A motion detector as claimed in claim 5 wherein said square wave generator is comprised of two gates and a CR components to produce uniform square waves of 2 to 4 Hz/sec when triggered by said control pulses.
10. A motion detector as claimed in claim 7 wherein said pulse display circuit is also connected to the output of said generator and is provided with a light emitting diode to provide a visual indication of each alarm pulse generated by said generator to help in the determination of the effective range of said detection signal field.
11. A motion detector as claimed in claim 1 wherein said transmitter is an electromagnetic wave transmitter.
12. A motion detector as claimed in claim 1 wherein said transmitter is an ultrasonic sound generator for transmitting a detection field at a doppler frequency rate;
said receiver being an ultrasonic receiver having a transducer receiver, amplifying stages and a phase detec-tion circuit.
said receiver being an ultrasonic receiver having a transducer receiver, amplifying stages and a phase detec-tion circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000397995A CA1197916A (en) | 1982-03-10 | 1982-03-10 | Motion detector signal processing circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000397995A CA1197916A (en) | 1982-03-10 | 1982-03-10 | Motion detector signal processing circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1197916A true CA1197916A (en) | 1985-12-10 |
Family
ID=4122258
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000397995A Expired CA1197916A (en) | 1982-03-10 | 1982-03-10 | Motion detector signal processing circuit |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1197916A (en) |
-
1982
- 1982-03-10 CA CA000397995A patent/CA1197916A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |