A device, comprising: a first signal source located at a first place, wherein the first signal source is configured to emit a first light beam to a surface of a living body; a first signal detecting device located at a second place, wherein the first signal detecting device is configured to detect a first signal reflected by the living body, the first signal being associated with a first penetration depth of the first light beam penetrating into the living body; a second signal detecting device located at a third place, wherein the second signal detecting device is configured to detect a second signal reflected by the living body, the second signal being associated with a second penetration depth of the first light beam penetrating into the living body but different from the first signal, each of the first signal source, the first signal detecting device, and the second signal detecting device being at a distance above the surface of the living body, wherein the first penetration depth of the first light beam penetrating into the living body relates to a distance between the first place and the second place; the second penetration depth of the first light beam penetrating into the living body relates to a distance between the first place and the third place, the distance between the first place and the second place is greater than the distance between the first place and the third place, and the first penetration depth is deeper than the second penetration depth; each of the first signal and the second signal includes a vital sign component and a motion component of the living body, a ratio of the vital sign component included in the first signal being larger than a ratio of the vital sign component included in the second signal; and a processor configured to determine the vital signal of the living body by performing, based on the first signal and the second signal, correction with respect to the motion using an adaptive filter. a first signal source located at a first place, wherein the first signal source is configured to emit a first light beam to a surface of a living body; a first signal detecting device located at a second place, wherein the first signal detecting device is configured to detect a first signal reflected by the living body, the first signal being associated with a first penetration depth of the first light beam penetrating into the living body; a second signal detecting device located at a third place, wherein the second signal detecting device is configured to detect a second signal reflected by the living body, the second signal being associated with a second penetration depth of the first light beam penetrating into the living body but different from the first signal, each of the first signal source, the first signal detecting device, and the second signal detecting device being at a distance above the surface of the living body, wherein the first penetration depth of the first light beam penetrating into the living body relates to a distance between the first place and the second place; the second penetration depth of the first light beam penetrating into the living body relates to a distance between the first place and the third place, the distance between the first place and the second place is greater than the distance between the first place and the third place, and the first penetration depth is deeper than the second penetration depth; each of the first signal and the second signal includes a vital sign component and a motion component of the living body, a ratio of the vital sign component included in the first signal being larger than a ratio of the vital sign component included in the second signal; and the first penetration depth of the first light beam penetrating into the living body relates to a distance between the first place and the second place; the second penetration depth of the first light beam penetrating into the living body relates to a distance between the first place and the third place, the distance between the first place and the second place is greater than the distance between the first place and the third place, and the first penetration depth is deeper than the second penetration depth; each of the first signal and the second signal includes a vital sign component and a motion component of the living body, a ratio of the vital sign component included in the first signal being larger than a ratio of the vital sign component included in the second signal; and a processor configured to determine the vital signal of the living body by performing, based on the first signal and the second signal, correction with respect to the motion using an adaptive filter.