Device and method for a sensor

A combined sensing device, comprising:

• a first sensor, directed substantially vertically down in relation to an identified orientation of the combined sensing device;
• at least one second sensor, directed substantially diagonally forward in relation to said identified orientation of said combined sensing device;
• and
• at least one hardware processor, electrically connected to said first sensor and said at least one second sensor and adapted to:
• receive at least one first signal from said first sensor or said at least one second sensor indicating a person's presence in a monitored premises;
• and
• until receiving at least one second signal from said first sensor or said at least one second sensor indicating an absence of said person from said monitored premises:
• during a predetermined delay time after receiving said first signal, determine whether one or more expected signals are received from said first sensor or said at least one second sensor;
• and
• determine an alarm system operation to be taken subject to said one or more expected signals not being received, according to said determination.