A system 1 for remote sensing of information to be transmitted, said system 1 comprising; an optical time-domain reflectometer, OTDR, 2 adapted to transmit an optical probe signal OPS into an optical fiber 3 and to measure a backscattered signal power; and at least one electro-optical signaling unit 4 connected to said optical fiber 3, wherein the electro-optical signaling unit 4 is configured to change an attenuation and/or a reflection of the optical probe signal OPS depending on at least one signal provided by one or more signal sources 5 in response to the information to be transmitted.

A constant current driving circuit and a corresponding photoelectric smoke alarm circuit are provided. The constant current driving circuit includes a reference voltage source module (1), a linear voltage regulator module (3), a level conversion module (2), a current mirror module (4) and a first NMOS transistor. The linear voltage regulator module (3) may control turning on and turning off thereof according to actual requirements, thus electrical energy loss may effectively be reduced for some periodically used devices. The constant current driving circuit and the corresponding photoelectric smoke alarm circuit may provide a constant current source, so that auxiliary output performance remains stable within a full temperature range, a certain timing sequence requirement is met, no standby power is consumed when not working, performance is stable, power consumption is low, and application range is wide.

A constant current driving circuit and a corresponding photoelectric smoke alarm circuit are provided. The constant current driving circuit includes a reference voltage source module (1), a linear voltage regulator module (3), a level conversion module (2), a current mirror module (4) and a first NMOS transistor. The linear voltage regulator module (3) may control turning on and turning off thereof according to actual requirements, thus electrical energy loss may effectively be reduced for some periodically used devices. The constant current driving circuit and the corresponding photoelectric smoke alarm circuit may provide a constant current source, so that auxiliary output performance remains stable within a full temperature range, a certain timing sequence requirement is met, no standby power is consumed when not working, performance is stable, power consumption is low, and application range is wide.

Embodiments of this disclosure provide a smoke detection method and apparatus. The apparatus includes a processor configured to detect foreground blobs in images of a plurality of frames in a video; determine motion areas of detected foreground blobs; determine a first degree of overlapping of the foreground blobs in images of at least two frames, and/or determine a second degree of overlapping of the foreground blobs and motion areas to which the foreground blobs correspond; determine interfering foreground blobs according to the first degree of overlapping and/or the second degree of overlapping; and extract features from motion areas of remaining foreground blobs with the interfering foreground blobs being removed, and detect smoke according to the features. With the embodiments of this disclosure, accuracy of smoke detection may be increased, and false detection resulted from such interfering objects as water blobs, or light spots, etc., may be avoided.

Embodiments of this disclosure provide a smoke detection method and apparatus. The apparatus includes a processor configured to detect foreground blobs in images of a plurality of frames in a video; determine motion areas of detected foreground blobs; determine a first degree of overlapping of the foreground blobs in images of at least two frames, and/or determine a second degree of overlapping of the foreground blobs and motion areas to which the foreground blobs correspond; determine interfering foreground blobs according to the first degree of overlapping and/or the second degree of overlapping; and extract features from motion areas of remaining foreground blobs with the interfering foreground blobs being removed, and detect smoke according to the features. With the embodiments of this disclosure, accuracy of smoke detection may be increased, and false detection resulted from such interfering objects as water blobs, or light spots, etc., may be avoided.

A fire detection system includes a transmitter including a light source that sends an optical signal and a receiver including a detector that detects the optical signal sent from the light source through a predetermined light propagation section, a signal processing unit that calculates at least one of a first gas concentration, a first smoke concentration, and a first temperature in the light propagation section based on the optical signal, a sensor that acquires at least one of a second gas concentration, a second smoke concentration, and a second temperature in the surroundings, and a determiner that determines whether there is a fire by comparing at least one of the first gas concentration, the first smoke concentration, and the first temperature with at least one of the second gas concentration, the second smoke concentration, and the second temperature in the surroundings.

A fire detection system includes a transmitter including a light source that sends an optical signal and a receiver including a detector that detects the optical signal sent from the light source through a predetermined light propagation section, a signal processing unit that calculates at least one of a first gas concentration, a first smoke concentration, and a first temperature in the light propagation section based on the optical signal, a sensor that acquires at least one of a second gas concentration, a second smoke concentration, and a second temperature in the surroundings, and a determiner that determines whether there is a fire by comparing at least one of the first gas concentration, the first smoke concentration, and the first temperature with at least one of the second gas concentration, the second smoke concentration, and the second temperature in the surroundings.

An electronic device includes a driver circuit embodied on an IC chip. The driver circuit includes a threshold voltage selection circuit that is coupled to receive a horn comparator threshold setting and to use the horn comparator threshold setting to provide a horn comparator threshold voltage. The driver circuit also includes a comparator that has a non-inverting input coupled to a first pin and an inverting input coupled to receive the horn comparator threshold voltage.

An electronic device includes a driver circuit embodied on an IC chip. The driver circuit includes a threshold voltage selection circuit that is coupled to receive a horn comparator threshold setting and to use the horn comparator threshold setting to provide a horn comparator threshold voltage. The driver circuit also includes a comparator that has a non-inverting input coupled to a first pin and an inverting input coupled to receive the horn comparator threshold voltage.

A smoke detector includes a laser light source to provide incident light. The smoke detector also includes a Fabry-Perot etalon to transmit some incoming light, which is produced from the incident light, as transmitted light. Smoke particles in a cavity of the Fabry-Perot etalon affect an intensity of one or more wavelengths of the transmitted light.