Recording activity detection
Systems, methods, and techniques for detecting the recording activity of a sensor are described. A monitoring system includes a sensor that is configured to generate sensor data, as well as a failsafe circuit that is configured to monitor an electronic signal of the sensor and determine that the sensor is recording. The system can further include a control unit that receives indication from the failsafe circuit that the sensor is recording and, based on determining that the control unit did not request the sensor to record or that the control unit is not aware that the sensor is recording, the system outputs a signal, e.g. to an indicator light, indicating that the sensor is recording.
1. A monitoring system that is configured to monitor a property, the monitoring system comprising:
a sensor that is configured to:
generate sensor data that reflects an attribute of a property;
encode the sensor data in a signal; and
transmit the signal;
a failsafe circuit that is configured to:
receive the signal;
determine whether the signal includes the sensor data; and
based on determining whether the signal includes the sensor data, generate first data indicating whether the sensor is generating the sensor data; and
a monitor control unit that is configured to:
receive the first data indicating whether the sensor is generating the sensor data; and
based on the first data indicating whether the sensor is generating the sensor data, provide, for output, data indicating whether the sensor is generating the sensor data.
2. The system of claim 1 , wherein the failsafe circuit is included in the sensor.
3. The system of claim 1 , wherein the failsafe circuit is separate from the sensor.
4. The system of claim 1 , wherein the sensor is configured to:
encode data packets that indicate the sensor is communicating with the monitor control unit.
5. The system of claim 4 , wherein the failsafe circuit is configured to:
determine whether the signal includes the sensor data by determining whether the signal encodes (i) the data packets that indicate the sensor is communicating with the monitor control unit and (ii) additional data.
6. The system of claim 1 , wherein:
the failsafe circuit is configured to:
determine whether the signal includes the sensor data by determining that the signal includes the sensor data;
generate first data indicating whether the sensor is generating the sensor data by generating the first data indicating that the sensor is generating the sensor data; and
the monitor control unit is configured to:
receive the first data indicating whether the sensor is generating the sensor data by receiving the first data indicating that the sensor is generating the sensor data.
7. The system of claim 1 , wherein:
the failsafe circuit is configured to:
determine whether the signal includes the sensor data by determining that the signal does not include the sensor data;
generate first data indicating whether the sensor is generating the sensor data by generating the first data indicating that the sensor is not generating the sensor data; and
the monitor control unit is configured to:
receive the first data indicating whether the sensor is generating the sensor data by receiving the first data indicating that the sensor is not generating the sensor data.
8. The system of claim 1 , wherein the failsafe circuit is configured to:
monitor an electronic signal of the sensor by monitoring a voltage of an electronic signal of the sensor;
based on the voltage of the electronic signal of the sensor, generate a voltage value;
compare the voltage value to a voltage threshold;
determine that the voltage value satisfies the voltage threshold; and
determine that the sensor is generating the sensor data based on determining that the voltage value satisfies the voltage threshold.
9. The system of claim 8 , wherein the fail safe circuit is configured to generate the voltage value by generating the voltage value based on a root-mean-square voltage of the electronic signal of the sensor.
10. The system of claim 8 , wherein the failsafe circuit is configured to:
monitor additional data output by the sensor while the failsafe circuit receives an indication that the sensor is generating sensor data; and
based on a voltage of the additional data output by the sensor while the failsafe circuit receives an indication that the sensor is generating sensor data, generate the voltage threshold.
11. The system of claim 1 , wherein the monitor control unit is configured to provide, for output, data indicating that the sensor is generating the sensor data by providing, for output to the sensor, an instruction to activate a notification light of the sensor.
12. The system of claim 1 , wherein the monitor control unit is configured to provide, for output, data indicating that the sensor is generating the sensor data by providing, for output to a resident of the property, a notification that the sensor is generating the sensor data.
13. The system of claim 1 , wherein the failsafe circuit is configured to:
based on monitoring an electronic signal of the sensor:
identify a token packet that indicates the sensor and the monitor control unit are communicating; and
determine that the sensor is generating the sensor data by determining that the electronic signal of the sensor includes the token packet and additional data.
14. A computer-implemented method comprising:
receiving, from a sensor and by a monitoring system that is configured to monitor a property, a signal;
determining, by the monitoring system, whether the signal includes sensor data that reflects an attribute of the property;
based on determining whether the signal includes the sensor data, generating first data indicating whether the sensor is generating the sensor data; and
based on the first data indicating whether the sensor is generating the sensor data, provide, for output, data indicating whether the sensor is generating the sensor data.
15. The method of claim 14 , wherein the sensor is configured to:
encode data packets that indicate the sensor is communicating with the monitoring system.
16. The method of claim 15 , wherein:
determining whether the signal includes the sensor data comprises determining whether the signal encodes (i) the data packets that indicate the sensor is communicating with the monitor control unit and (ii) additional data.
17. The method of claim 14 , wherein:
determining whether the signal includes the sensor data comprises determining that the electrical signal includes the sensor data.
18. The method of claim 14 , wherein:
determining whether the signal includes the sensor data comprises determining that the signal does not include the sensor data.
19. The system of claim 14 , wherein determining whether the signal includes sensor data that reflects the attribute of the property is performed by a failsafe circuit included in the sensor.
20. The method of claim 14 , wherein determining whether the signal includes sensor data that reflects the attribute of the property is performed by a failsafe circuit is separate from the sensor.