Systems and methods for detecting tampering with privacy notifiers in recording systems

1. A computer-implemented method, comprising:

activating, by a processor, a privacy notifier mechanism in a recording system to transmit a privacy notification signal when a camera in the recording system is in a ready state to capture images, wherein the privacy notifier mechanism includes a light emitting diode, LED;

comparing a measured discharge time of a charge accumulated on parasitic capacitances of the LED with a reference discharge time;

measuring a temperature of the LED in the recording system and temperature compensating a value of the reference discharge time used for comparison with the measured discharge time;

detecting blocking of the transmit of the privacy notification signal when the measured discharge time of the charge accumulated on the parasitic capacitances is greater than the reference discharge time; and

responsive to detecting blocking of the transmit of the privacy notification signal by the processor, disabling the camera.

2. The computer-implemented method of claim 1 , wherein the privacy notifier mechanism comprises a light emitting element which, in a first operation state, transmits the privacy notification signal by emitting light, and in another second operation state is configured to detect blocking of light emitted by the light emitting element.

3. The computer-implemented method of claim 1 , wherein activating, by the processor, the privacy notifier mechanism includes forward biasing the LED to emit light.

4. The computer-implemented method of claim 3 , wherein detecting blocking of the transmit of the privacy notification signal includes detecting blocking of light emitted by the LED.

5. The computer-implemented method of claim 3 , wherein the LED is placed across two general purpose input output (GPIO) pins of a controller, and the method includes: applying logic high-low signals to the GPIO pins for forward biasing the LED to emit light, and for reverse biasing the LED to place the LED in a photodetector mode.

6. The computer-implemented method of claim 5 further including reverse biasing the LED to place the LED in the photodetector mode and detecting blocking of the transmit of the privacy notification signal.

7. The computer-implemented method of claim 6 further including measuring ambient light entering the LED in the photodetector mode and comparing that with ambient light sensed through the camera.

8. The computer-implemented method of claim 5 , wherein measuring the discharge time of the charge accumulated on the parasitic capacitances of the LED in the photodetector mode includes measuring a voltage on a GPIO pin as a function of time and identifying a time it takes the voltage to cross a logic threshold as the discharge time.

9. The computer-implemented method of claim 1 , wherein the privacy notifier mechanism comprises a speaker, and wherein activating, by the processor, the privacy notifier mechanism includes activating the speaker to broadcast a sound signal indicative of a presence of the camera.

10. The computer-implemented method of claim 9 , wherein detecting blocking of the transmit of the privacy notification signal includes comparing speaker sounds received by a microphone with a reference speaker sound.

11. The computer-implemented method of claim 10 , wherein detecting blocking of transmission of the privacy notification signal comprises:

detecting an absence or a reduction in an intensity of the reference speaker sound.

12. A system, comprising:

a camera unit including a camera; and

a controller including:

at least one processor; and

a memory storing instructions that, when executed by the at least one processor, cause the at least one processor to:

activate a privacy notifier mechanism in a recording system to transmit a privacy notification signal when a camera in the recording system is in a ready state to capture images, the privacy notifier mechanism including a light emitting diode, LED;

compare a measured discharge time of a charge accumulated on parasitic capacitances of the LED with a reference discharge time;

measure a temperature of the LED in the recording system and temperature compensate a value of the reference discharge time used for comparison with the measured discharge time;

detect blocking of the transmit of the privacy notification signal when the measured discharge time of the charge accumulated on the parasitic capacitances is greater than the reference discharge time; and

responsive to detecting blocking of the transmit of the privacy notification signal, disable the camera.

13. A system, comprising:

a camera unit including:

a camera; and

a light emitting diode, LED; and

a controller including:

at least one processor; and

a memory storing instructions that, when executed by the at least one processor, cause the at least one processor to:

forward bias the LED to emit light when the camera is in a ready state to capture images;

periodically, reverse bias the LED to place the LED in a photodetector mode to detect blocking of the LED; and

measure a discharge time of a charge accumulated on parasitic capacitances of the LED in the photodetector mode;

compare the measured discharge time of the charge accumulated on parasitic capacitances with a reference discharge time;

measure a temperature of the LED and temperature compensate a value of the reference discharge time used for comparison with the measured discharge time;

detect blocking of the LED when the measured discharge time of the charge accumulated on parasitic capacitances is greater than the reference discharge time; and

responsive to detecting blocking of the LED, disable the camera.

14. The system of claim 13 , wherein the LED is placed across two general purpose input output (GPIO) pins of the controller, and wherein the instructions cause the processor to apply logic high-low signals to the GPIO pins for forward biasing the LED to emit light, and for reverse biasing the LED to place the LED in the photodetector mode.

15. The system of claim 13 , wherein the instructions cause the processor to measure ambient light entering the LED in the photodetector mode.

16. The system of claim 14 , wherein the instructions cause the processor to:

measure the discharge time of the charge accumulated on the parasitic capacitances of the LED in the photodetector mode by measuring a voltage on a GPIO pin as a function of time and identifying a time it takes the voltage to cross a logic threshold as the discharge time.

17. The system of claim 13 , wherein the camera unit further comprises:

a speaker; and

a microphone; and

wherein the instructions cause the processor to activate the speaker to transmit a sound signal indicative of a presence of the camera capable of capturing images of bystanders, and compare speaker sounds picked up by the microphone with a reference speaker sound.

18. The system of claim 17 , wherein the instructions further cause the processor to identify an instance of tampering with the speaker when the speaker sounds picked up by on-board microphone show an absence of, or a reduction in an intensity of the reference speaker sound.