Operation Principles

Principle of Logging Activity:
Activity is detected by the motion (infrared) sensor (specifications) and mediated by a flip-flop wiring (a system discriminating exactly two states, for example 0/1, yes/no, true/false, “flip”/”flop”, etc.). The motion sensor is constantly sending a signal to the flip-flop wiring. This signal changes with the varying excitation of the motion sensor caused by a moving object emitting warmth (infrared) radiation within the detection range. Once the flip-flop wiring has received an altered signal, its state changes from the first state (default state, 0) to the second state (1). Not regarding a probably continuing alteration of the signal received from the motion sensor, the flip-flop wiring remains in the second state (1) until it is explicitly reset to the first state (0) by an external pulse. Then, the procedure is initiated again. The present state of the flip-flop wiring is read with a resolution depending on the interval granularity (default setting = 1s) of the recording interval of the data logger. If the flip-flop’s state is 1 because it has received an altered signal triggered by a moving object from the motion sensor at least once, the current activity value is increased by 1 and the flip-flop wiring is reset. This recurs until the period of the recording interval (default setting = 240s = 4min) has passed. The value resulting from this step-by-step increment by 1 is saved to the data logger’s data memory as the final activity value for this recording interval (and afterwards is reset to 0 for the next recording interval).

Principle of Logging Temperature/Relative Humidity:
The feature of logging temperature and relative humidity is well suited to monitor the ambient conditions in animal facility rooms.
The integrated sensors for temperature (specifications) and relative humidity are calibrated high precision sensors. They are mounted on the right inside of the data logger. Small holes in the lateral face of the data logger’s case serve as a linkage to the ambient conditions. The present value of each sensor is read when the period of one record interval (default setting is 240s = 4min) has passed and is immediately saved to the data memory.

Principle of Logging Light Intensity:
The feature of light intensity logging is predominantly designed to monitor the ambient light of animal facilities and to detect potential faults or failures.
The light sensor (specifications) has a high sensitivity (1 to. 20,000 lux) but it is not calibrated. So the measured values present only a general comparative idea of how much light there is in an area (sunlight v. shade, lights on/off, etc.) but not absolute values (also see Frequently Asked Questions). The sensor is mounted on the inside of the data logger, light admission is provided by an opening in the surface. The spectral response of the sensor emulates the human eye. Infrared wavelengths, emitted, for example, by halogen light, potentially interfering with light of the visible range are sharply attenuated. The measured light intensity values are influenced by several parameters. For example, similarly as with the human eye, the values vary with the direction from which the light reaches the sensor. Because of its high sensitivity minor changes in the light intensity may yield significant differences in the measured values. This has to be considered when inspecting the results of light intensity logging.
Light intensity is measured with the period of the interval granularity (default setting is 1s) of one recording interval. Each time, the present value of the light sensor is read 20 times with an interlude of one millisecond between the readings. (This procedure ensures that flickering of a light source caused by the mains voltage doesn’t influence the reading.) The average from these single sensor readings is temporarily stored as an intermediate result. When the period of one recording interval (default setting is 240s = 4min) has passed the average from the number of intermediate values resulting from the scanning rate of a record interval (= 240 in the case of the default settings) is saved as the final result for the light intensity.

Principle of Logging Analog Input (from External Sources):
The connector for external data accepts any input of analog signal sources. The analog-to-digital converter has a resolution of 10Bit and is integrated into the microcontroller running the data logger (specifications).
The analog input is accessed with the time resolution of the interval granularity (default setting = 1s) of the record interval. Each time, the present value of the analog-to-digital converter is read 20 times with an interlude of one millisecond between the readings. The average from these single readings is temporarily stored as an intermediate result. When the period of one record interval (default setting is 240s = 4min) has passed the average from the number of intermediate values resulting from the scanning rate of a record interval (= 240 in the case of the default settings) is saved as the final result of the analog input reading.

Principle of Logging Data from Logger Extensions (under development):
Future versions of the MOUSE-E-MOTION Universal Data Logger will provide the possibility to additionally connect logger extensions which currently are under development. One of these extensions is a unit which monitors the drinking water consumption of laboratory animals. It is based upon weight sensors which measure the (reducing) weight of up to 4 attached drinking bottles during water consumption with high accuracy and resolution.
The present value of a connected logger extension is read when the period of one record interval (default setting is 240s = 4min) has passed and is immediately saved to the data memory.