Abstract
A battery-powered, wireless gas sensing unit for measuring a gas concentration, the gas sensing unit comprising a first sensor, a second sensor, a battery unit, a wireless transmitter, a processor and a controller. The first sensor is adapted to frequently measure a value of a first parameter. The second sensor and the processor are controlled to measure the gas concentration only when the value of the first parameter or variation of the value of the first parameter exceeds a predefined first parameter threshold. The wireless transmitter is controlled to transmit the gas concentration only when the gas concentration exceeds a predefined concentration threshold.
Claims
1. A battery-powered, wireless gas sensing unit for measuring a gas concentration, said gas sensing unit comprising a first sensor, a second sensor, a battery unit, a wireless transmitter, a processor and a controller, wherein: said first sensor is adapted to frequently measure a value of a first parameter; said second sensor and said processor are controlled to measure said gas concentration only when said value of said first parameter or variation of said value of said first parameter exceeds a predefined first parameter threshold; and said wireless transmitter is controlled to transmit said gas concentration only when said gas concentration exceeds a predefined concentration threshold.
2. A gas sensing unit according to claim 1, wherein said first sensor comprises one or more of the group of: a temperature sensor; a humidity sensor; a presence sensor; a proximity sensor; a movement sensor.
3. The gas sensing unit according to claim 1, wherein said first sensor is adapted to periodically measure said value of said first parameter.
4. The gas sensing unit according to claim 3, wherein said first sensor is adapted to measure said value of said first parameter with a periodicity comprised between at least once per second and at least once per hour.
5. The gas sensing unit according to claim 1, wherein said second sensor comprises a Volatile Organic Compound sensor or VOC sensor.
6. The gas sensing unit according to claim 1, wherein said gas concentration is a CO2 concentration.
7. The gas sensing unit according to claim 1, wherein said processor is configured to calculate said CO2 concentration from output of said VOC sensor.
8. The gas sensing unit according to claim 1, wherein said battery unit comprises a first battery and a second battery, and wherein said second battery is parallel connected to said first battery while said wireless transmitter transmits said gas concentration.
9. The gas sensing unit according to claim 1, wherein said gas sensing unit further comprises a calibration unit adapted to supply an electrical current to said second sensor prior to each measurement of said gas concentration, said electrical current being determined to bring said second sensor at a same operational working point.
10. The gas sensing unit according to claim 1, wherein said gas sensing unit further comprises: an Analog-to-Digital Converter or ADC, adapted to digitize output values of said second sensor; a high impedance current source, having an output coupled to said second sensor and being controlled to supply a current to said second sensor such that output values of said second sensor stay within a limited central interval of the operational range of said ADC; and said processor is configured to consider said current when calculating said gas concentration from said output values of said second sensor.
11. The gas sensing unit according to claim 1, further comprising an encrypting module, adapted to perform encryption prior to transmission.
12. The gas sensing unit according to claim 1, further comprising an error correction unit, adapted to perform error correction prior to transmission.
13. A method for measuring a gas concentration, said method comprising the steps of: frequently measuring a value of a first parameter; measuring said gas concentration only when said value of said first parameter or variation of said value of said first parameter exceeds a predefined first parameter threshold; and wirelessly transmitting said gas concentration only when said gas concentration exceeds a predefined concentration threshold.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] FIG. 1 schematically illustrates an embodiment of a battery-powered, wireless gas sensing unit according to the present invention.
[0055] FIG. 2 schematically illustrates an embodiment of a battery-powered, wireless gas sensing unit, wherein a first sensor comprises a temperature sensor and a humidity sensor.
[0056] FIG. 3 schematically illustrates an embodiment of a battery-powered, wireless gas sensing unit, wherein a second sensor comprises a VOC sensor from which a CO2 concentration is calculated.
[0057] FIG. 4 schematically illustrates an embodiment of a battery-powered, wireless gas sensing unit, wherein a battery unit comprises a first battery and a second battery.
[0058] FIG. 5 schematically illustrates an embodiment of a battery-powered, wireless gas sensing unit comprising a calibration unit.
[0059] FIG. 6 schematically illustrates an embodiment of a battery-powered, wireless gas sensing unit comprising an Analog-to-Digital Converter and a high impedance current source.
[0060] FIG. 7 schematically illustrates a front view of an embodiment of housing suitable for hosting a battery-powered, wireless gas sensing unit according to the present invention.
DETAILED DESCRIPTION OF EMBODIMENT(S)
[0061] According to an embodiment shown in FIG. 1, a battery-operated, wireless gas sensing unit 1 comprises a first sensor 101, a second sensor 102, a battery unit 103, a wireless transmitter 104, a processor 105, a controller 106 and a memory 130. Crossing lines in FIG. 1 are not to be interpreted as connections. The first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 periodically. The first sensor 101 can for example measure a value 3 of a first parameter 10 every 30 seconds, every minute, every 2 minutes, every 5 minutes, every 10 minutes, every 30 minutes, every hour, every 12 hours, or every 24 hours, etc. According to an alternative embodiment, the first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 several times per minute, or several times per hour, or several times per day, etc. A value 3 of a first parameter 10 may be stored in the memory 130. The controller 106 compares the value 3 of the first parameter 10 measured by the first sensor 101 to a predefined first parameter threshold 4. The predefined first parameter threshold 4 may be programmed in the controller 106. According to an alternative embodiment, the predefined first parameter threshold 4 is remotely received by a wireless transceiver comprising the wireless transmitter 104 and sent to the controller 106.
[0062] According to an alternative embodiment, the predefined first parameter threshold 4 is retrieved from the memory 130. The value of the predefined first parameter threshold 4 may be modified. A value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is equal to or larger than the first parameter threshold 4. According to an alternative embodiment, a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is smaller than or equal to the first parameter threshold 4. Only when a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 does the controller 106 controls the second sensor 102 and the processor 105 to measure a gas concentration 2. A gas concentration 2 may be a carbon monoxide or CO concentration, a Volatile Organic Compounds or VOCs concentration, a radon concentration, etc. A gas concentration 2 may be stored in the memory 130. The controller 106 compares the gas concentration 2 measured by the second sensor 102 to a predefined concentration threshold 5. The predefined concentration threshold 5 may be programmed in the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is remotely received by the wireless transmitter 104 and sent to the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is retrieved from the memory 130. The value of the predefined concentration threshold 5 may be modified. A gas concentration 2 exceeds the predefined concentration threshold 5 when the gas concentration 2 is equal to or larger than the predefined concentration threshold 5. According to an alternative embodiment, a gas concentration 2 exceeds the predefined concentration threshold 5 when the gas concentration 2 is smaller than or equal to the predefined concentration threshold 5. Only when a gas concentration 2 exceeds the predefined concentration threshold 5 does the controller 106 controls the wireless transmitter 104 to transmit the gas concentration 2.
[0063] According to an embodiment shown in FIG. 2, a battery-operated, wireless gas sensing unit 1 comprises a first sensor 101, a second sensor 102, a battery unit 103, a wireless transmitter 104, a processor 105, a controller 106 and a memory 130. Crossing lines in FIG. 2 are not to be interpreted as connections. Components having identical reference numbers to components in FIG. 1 perform the same function. The first sensor 101 comprises a temperature sensor 111 and a humidity sensor 112. According to an alternative embodiment, the first sensor 101 comprises a temperature sensor 111 or a humidity sensor 112. According to an alternative embodiment, the first sensor 101 comprises one or more of the group of a temperature sensor 111, a humidity sensor 112, a presence sensor, a proximity sensor, a movement sensor. A value 3 of the first parameter 10 measured by the first sensor 101 is a value 3 of the temperature of the environment of the gas sensing unit 1. According to an alternative embodiment, a value 3 of the first parameter 10 measured by the first sensor 101 is a value 3 of the humidity of the environment of the gas sensing unit 1. According to an alternative embodiment, the first parameter 10 measured by the first sensor 101 is any combination of the values 3 of the temperature and the humidity of the environment of the gas sensing unit 1. The first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 periodically. The first sensor 101 can for example measure a value 3 of a first parameter 10 every 30 seconds, every minute, every 2 minutes, every 5 minutes, every 10 minutes, every 30 minutes, every hour, every 12 hours, or every 24 hours, etc. According to an alternative embodiment, the first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 several times per minute, or several times per hour, or several times per day, etc. A value 3 of a first parameter 10 may be stored in the memory 130. The controller 106 compares the value 3 of the first parameter 10 measured by the first sensor 101 to a predefined first parameter threshold 4. The predefined first parameter threshold 4 may be programmed in the controller 106. According to an alternative embodiment, the predefined first parameter threshold 4 is remotely received by a wireless transceiver comprising the wireless transmitter 104 and sent to the controller 106. According to an alternative embodiment, the predefined first parameter threshold 4 is retrieved from the memory 130. The value of the predefined first parameter threshold 4 may be modified. A value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is equal to or larger than the first parameter threshold 4. According to an alternative embodiment, a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is smaller than or equal to the first parameter threshold 4. Only when a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 does the controller 106 controls the second sensor 102 and the processor 105 to measure a gas concentration 2. A gas concentration 2 may be a carbon monoxide or CO concentration, a Volatile Organic Compounds or VOCs concentration, a radon concentration, etc. A gas concentration 2 may be stored in the memory 130. The controller 106 compares the gas concentration 2 measured by the second sensor 102 to a predefined concentration threshold 5. The predefined concentration threshold 5 may be programmed in the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is remotely received by the wireless transmitter 104 and sent to the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is retrieved from the memory 130. The value of the predefined concentration threshold 5 may be modified. A gas concentration 2 exceeds the predefined concentration threshold 5 when the gas concentration 2 is equal to or larger than the predefined concentration threshold 5. According to an alternative embodiment, a gas concentration 2 exceeds the predefined concentration threshold 5 when the gas concentration 2 is smaller than or equal to the predefined concentration threshold 5. Only when a gas concentration 2 exceeds the predefined concentration threshold 5 does the controller 106 controls the wireless transmitter 104 to transmit the gas concentration 2.
[0064] According to an embodiment shown in FIG. 3, a battery-operated, wireless gas sensing unit 1 comprises a first sensor 101, a second sensor 102, a battery unit 103, a wireless transmitter 104, a processor 105, a controller 106 and a memory 130. Crossing lines in FIG. 3 are not to be interpreted as connections. Components having identical reference numbers to components in FIG. 2 perform the same function. The first sensor 101 comprises a temperature sensor 111 and a humidity sensor 112. According to an alternative embodiment, the first sensor 101 comprises a temperature sensor 111 or a humidity sensor 112. According to an alternative embodiment, the first sensor 101 comprises one or more of the group of a temperature sensor 111, a humidity sensor 112, a presence sensor, a proximity sensor, a movement sensor. A value 3 of the first parameter 10 measured by the first sensor 101 is a value 3 of the temperature of the environment of the gas sensing unit 1. According to an alternative embodiment, a value 3 of the first parameter 10 measured by the first sensor 101 is a value 3 of the humidity of the environment of the gas sensing unit 1. According to an alternative embodiment, the first parameter 10 measured by the first sensor 101 is any combination of the values 3 of the temperature and the humidity of the environment of the gas sensing unit 1. The first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 periodically. The first sensor 101 can for example measure a value 3 of a first parameter 10 every 30 seconds, every minute, every 2 minutes, every 5 minutes, every 10 minutes, every 30 minutes, every hour, every 12 hours, or every 24 hours, etc. According to an alternative embodiment, the first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 several times per minute, or several times per hour, or several times per day, etc. A value 3 of a first parameter 10 may be stored in the memory 130. The controller 106 compares the value 3 of the first parameter 10 measured by the first sensor 101 to a predefined first parameter threshold 4. The predefined first parameter threshold 4 may be programmed in the controller 106. According to an alternative embodiment, the predefined first parameter threshold 4 is remotely received by a wireless transceiver comprising the wireless transmitter 104 and sent to the controller 106. According to an alternative embodiment, the predefined first parameter threshold 4 is retrieved from the memory 130. The value of the predefined first parameter threshold 4 may be modified. A value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is equal to or larger than the first parameter threshold 4. According to an alternative embodiment, a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is smaller than or equal to the first parameter threshold 4. Only when a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 does the controller 106 controls the second sensor 102 and the processor 105 to measure a gas concentration 2. The second sensor 102 comprises a Volatile Organic Compound sensor 121 or VOC sensor 121. The VOC sensor 121 is for example a microelectromechanical system or MEM. The dimensions of the MEM are for example 2×3 millimetres, or a few millimetres square. The MEMs have a low power consumption, for example less than hundreds of milli-Watt, and preferably even less than tens of milli-Watt. The VOC sensor 121 is heated up to a temperature between 350° C. and 450° C., preferably to 400° C. A gas concentration 2 may be a carbon monoxide or CO concentration, a Volatile Organic Compounds or VOCs concentration, a radon concentration, etc. A gas concentration 2 may be stored in the memory 130. The processor 105 calculates a CO2 concentration 8 from output 7 of the VOC sensor 121. The controller 106 compares the CO2 concentration 8 calculated from output of the VOC sensor 121 to a predefined concentration threshold 5. The controller 106 may also compare a gas concentration 2 measured by the second sensor 102 to a predefined concentration threshold 5. The predefined concentration threshold 5 may be programmed in the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is remotely received by the wireless transmitter 104 and sent to the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is retrieved from the memory 130. The value of the predefined concentration threshold 5 may be modified. A CO2 concentration 8 exceeds the predefined concentration threshold 5 when the CO2 concentration 8 is equal to or larger than the predefined concentration threshold 5. According to an alternative embodiment, a CO2 concentration 8 exceeds the predefined concentration threshold 5 when the CO2 concentration 8 is smaller than or equal to the predefined concentration threshold 5. Only when a CO2 concentration 8 exceeds the predefined concentration threshold 5 does the controller 106 controls the wireless transmitter 104 to transmit the CO2 concentration 8.
[0065] According to an embodiment shown in FIG. 4, a battery-operated, wireless gas sensing unit 1 comprises a first sensor 101, a second sensor 102, a battery unit 103, a wireless transmitter 104, a processor 105, a controller 106 and a memory 130. Crossing lines in FIG. 4 are not to be interpreted as connections. Components having identical reference numbers to components in FIG. 3 perform the same function. The first sensor 101 comprises a temperature sensor 111 and a humidity sensor 112. According to an alternative embodiment, the first sensor 101 comprises a temperature sensor 111 or a humidity sensor 112. According to an alternative embodiment, the first sensor 101 comprises one or more of the group of a temperature sensor 111, a humidity sensor 112, a presence sensor, a proximity sensor, a movement sensor. A value 3 of the first parameter 10 measured by the first sensor 101 is a value 3 of the temperature of the environment of the gas sensing unit 1. According to an alternative embodiment, a value 3 of the first parameter 10 measured by the first sensor 101 is a value 3 of the humidity of the environment of the gas sensing unit 1. According to an alternative embodiment, the first parameter 10 measured by the first sensor 101 is any combination of the values 3 of the temperature and the humidity of the environment of the gas sensing unit 1. The first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 periodically. The first sensor 101 can for example measure a value 3 of a first parameter 10 every 30 seconds, every minute, every 2 minutes, every 5 minutes, every 10 minutes, every 30 minutes, every hour, every 12 hours, or every 24 hours, etc. According to an alternative embodiment, the first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 several times per minute, or several times per hour, or several times per day, etc. A value 3 of a first parameter 10 may be stored in the memory 130. The controller 106 compares the value 3 of the first parameter 10 measured by the first sensor 101 to a predefined first parameter threshold 4. The predefined first parameter threshold 4 may be programmed in the controller 106. According to an alternative embodiment, the predefined first parameter threshold 4 is remotely received by a wireless transceiver comprising the wireless transmitter 104 and sent to the controller 106. According to an alternative embodiment, the predefined first parameter threshold 4 is retrieved from the memory 130. The value of the predefined first parameter threshold 4 may be modified. A value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is equal to or larger than the first parameter threshold 4. According to an alternative embodiment, a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is smaller than or equal to the first parameter threshold 4. Only when a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 does the controller 106 controls the second sensor 102 and the processor 105 to measure a gas concentration 2. The second sensor 102 comprises a Volatile Organic Compound sensor 121 or VOC sensor 121. A gas concentration 2 may for example be a CO2 concentration 8. According to alternative embodiments, a gas concentration 2 may be a carbon monoxide or CO concentration, a Volatile Organic Compound or VOC concentration, a radon concentration, etc. A gas concentration 2 may be stored in the memory 130. The processor 105 calculates a CO2 concentration 8 from output 7 of the VOC sensor 121. The controller 106 compares the CO2 concentration 8 calculated from output of the VOC sensor 121 to a predefined concentration threshold 5. The controller 106 may also compare a gas concentration 2 measured by the second sensor 102 to a predefined concentration threshold 5. The predefined concentration threshold 5 may be programmed in the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is remotely received by the wireless transmitter 104 and sent to the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is retrieved from the memory 130. The value of the predefined concentration threshold 5 may be modified. A CO2 concentration 8 exceeds the predefined concentration threshold 5 when the CO2 concentration 8 is equal to or larger than the predefined concentration threshold 5. According to an alternative embodiment, a CO2 concentration 8 exceeds the predefined concentration threshold 5 when the CO2 concentration 8 is smaller than or equal to the predefined concentration threshold 5. Only when a CO2 concentration 8 exceeds the predefined concentration threshold 5 does the controller 106 controls the wireless transmitter 104 to transmit the CO2 concentration 8. The battery unit 103 comprises a first battery 131 and a second battery 132. The second battery 132 is parallel connected to the first battery 131 while the wireless transmitter 104 transmits the CO2 concentration 8. According to an alternative embodiment, the second battery 132 is parallel connected to the first battery 131 while the wireless transmitter 104 transmits the gas concentration 2.
[0066] According to an embodiment shown in FIG. 5, a battery-operated, wireless gas sensing unit 1 comprises a first sensor 101, a second sensor 102, a battery unit 103, a wireless transmitter 104, a processor 105, a controller 106, a memory 130 and a calibration unit 107. Crossing lines in FIG. 5 are not to be interpreted as connections. Components having identical reference numbers to components in FIG. 4 perform the same function. The first sensor 101 comprises a temperature sensor 111 and a humidity sensor 112. According to an alternative embodiment, the first sensor 101 comprises a temperature sensor 111 or a humidity sensor 112. According to an alternative embodiment, the first sensor 101 comprises one or more of the group of a temperature sensor 111, a humidity sensor 112, a presence sensor, a proximity sensor, a movement sensor. A value 3 of the first parameter 10 measured by the first sensor 101 is a value 3 of the temperature of the environment of the gas sensing unit 1. According to an alternative embodiment, a value 3 of the first parameter 10 measured by the first sensor 101 is a value 3 of the humidity of the environment of the gas sensing unit 1. According to an alternative embodiment, the first parameter 10 measured by the first sensor 101 is any combination of the values 3 of the temperature and the humidity of the environment of the gas sensing unit 1. The first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 periodically. The first sensor 101 can for example measure a value 3 of a first parameter 10 every 30 seconds, every minute, every 2 minutes, every 5 minutes, every 10 minutes, every 30 minutes, every hour, every 12 hours, or every 24 hours, etc. According to an alternative embodiment, the first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 several times per minute, or several times per hour, or several times per day, etc. A value 3 of a first parameter 10 may be stored in the memory 130. The controller 106 compares the value 3 of the first parameter 10 measured by the first sensor 101 to a predefined first parameter threshold 4. The predefined first parameter threshold 4 may be programmed in the controller 106. According to an alternative embodiment, the predefined first parameter threshold 4 is remotely received by a wireless transceiver comprising the wireless transmitter 104 and sent to the controller 106. According to an alternative embodiment, the predefined first parameter threshold 4 is retrieved from the memory 130. The value of the predefined first parameter threshold 4 may be modified. A value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is equal to or larger than the first parameter threshold 4. According to an alternative embodiment, a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is smaller than or equal to the first parameter threshold 4. Only when a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 does the controller 106 controls the second sensor 102 and the processor 105 to measure a gas concentration 2. The second sensor 102 comprises a Volatile Organic Compound sensor 121 or VOC sensor 121. A gas concentration 2 may for example be a CO2 concentration 8. According to alternative embodiments, a gas concentration 2 may be a carbon monoxide or CO concentration, a Volatile Organic Compound or VOC concentration, a radon concentration, etc. A gas concentration 2 may be stored in the memory 130. The processor 105 calculates a CO2 concentration 8 from output 7 of the VOC sensor 121. The controller 106 compares the CO2 concentration 8 calculated from output of the VOC sensor 121 to a predefined concentration threshold 5. The controller 106 may also compare a gas concentration 2 measured by the second sensor 102 to a predefined concentration threshold 5. The predefined concentration threshold 5 may be programmed in the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is remotely received by the wireless transmitter 104 and sent to the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is retrieved from the memory 130. The value of the predefined concentration threshold 5 may be modified. A CO2 concentration 8 exceeds the predefined concentration threshold 5 when the CO2 concentration 8 is equal to or larger than the predefined concentration threshold 5. According to an alternative embodiment, a CO2 concentration 8 exceeds the predefined concentration threshold 5 when the CO2 concentration 8 is smaller than or equal to the predefined concentration threshold 5. Only when a CO2 concentration 8 exceeds the predefined concentration threshold 5 does the controller 106 controls the wireless transmitter 104 to transmit the CO2 concentration 8. The battery unit 103 comprises a first battery 131 and a second battery 132. The second battery 132 is parallel connected to the first battery 131 while the wireless transmitter 104 transmits the CO2 concentration 8. According to an alternative embodiment, the second battery 132 is parallel connected to the first battery 131 while the wireless transmitter 104 transmits the gas concentration 2. Prior to each measurement of a gas concentration 2 by the second sensor 102, the calibration unit 107 supplies an electrical current 70 to the second sensor 102. According to an alternative embodiment, the calibration unit 107 supplies an electrical current 70 to the VOC sensor 121 prior to each measurement of a gas concentration 2 by the second sensor 102. The electrical current 70 is determined to bring the second sensor 102 at the same operational point. The electrical current 70 may be determined by the controller 106. According to an alternative embodiment, the electrical current 70 may be determined by the processor 105. According to an alternative embodiment, the electrical current 70 may be remotely programmed.
[0067] According to an embodiment shown in FIG. 6, a battery-operated, wireless gas sensing unit 1 comprises a first sensor 101, a second sensor 102, a battery unit 103, a wireless transmitter 104, a processor 105, a controller 106, a memory 130, a calibration unit 107, an Analog-to-Digital Converter or ADC 108, a high impedance current source 109, an encryption module 110 and an error correction unit 120. Crossing lines in FIG. 6 are not to be interpreted as connections. Components having identical reference numbers to components in FIG. 5 perform the same function. The first sensor 101 comprises a temperature sensor 111 and a humidity sensor 112. According to an alternative embodiment, the first sensor 101 comprises a temperature sensor 111 or a humidity sensor 112. According to an alternative embodiment, the first sensor 101 comprises one or more of the group of a temperature sensor 111, a humidity sensor 112, a presence sensor 113, a proximity sensor 114, a movement sensor 115. A value 3 of the first parameter 10 measured by the first sensor 101 is a value 3 of the temperature of the environment of the gas sensing unit 1. According to an alternative embodiment, a value 3 of the first parameter 10 measured by the first sensor 101 is a value 3 of the humidity of the environment of the gas sensing unit 1. According to an alternative embodiment, the first parameter 10 measured by the first sensor 101 is any combination of the values 3 of the temperature and the humidity of the environment of the gas sensing unit 1. The first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 periodically. The first sensor 101 can for example measure a value 3 of a first parameter 10 every 30 seconds, every minute, every 2 minutes, every 5 minutes, every 10 minutes, every 30 minutes, every hour, every 12 hours, or every 24 hours, etc. According to an alternative embodiment, the first sensor 101 frequently measures a value 3 of a first parameter 10. For example, the first sensor 101 measures a value 3 of a first parameter 10 several times per minute, or several times per hour, or several times per day, etc. A value 3 of a first parameter 10 may be stored in the memory 130. The controller 106 compares the value 3 of the first parameter 10 measured by the first sensor 101 to a predefined first parameter threshold 4. The predefined first parameter threshold 4 may be programmed in the controller 106. According to an alternative embodiment, the predefined first parameter threshold 4 is remotely received by a wireless transceiver comprising the wireless transmitter 104 and sent to the controller 106. According to an alternative embodiment, the predefined first parameter threshold 4 is retrieved from the memory 130. The value of the predefined first parameter threshold 4 may be modified. A value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is equal to or larger than the first parameter threshold 4. According to an alternative embodiment, a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 when the value 3 is smaller than or equal to the first parameter threshold 4. Only when a value 3 of the first parameter 10 exceeds the predefined first parameter threshold 4 does the controller 106 controls the second sensor 102 and the processor 105 to measure a gas concentration 2. The second sensor 102 comprises a Volatile Organic Compound sensor 121 or VOC sensor 121. A gas concentration 2 may for example be a CO2 concentration 8. According to alternative embodiments, a gas concentration 2 may be a carbon monoxide or CO concentration, a Volatile Organic Compound or VOC concentration, a radon concentration, etc. A gas concentration 2 may be stored in the memory 130. The processor 105 calculates a CO2 concentration 8 from output 7 of the VOC sensor 121. The controller 106 compares the CO2 concentration 8 calculated from output of the VOC sensor 121 to a predefined concentration threshold 5. The controller 106 may also compare a gas concentration 2 measured by the second sensor 102 to a predefined concentration threshold 5. The predefined concentration threshold 5 may be programmed in the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is remotely received by the wireless transmitter 104 and sent to the controller 106. According to an alternative embodiment, the predefined concentration threshold 5 is retrieved from the memory 130. The value of the predefined concentration threshold 5 may be modified. A CO2 concentration 8 exceeds the predefined concentration threshold 5 when the CO2 concentration 8 is equal to or larger than the predefined concentration threshold 5. According to an alternative embodiment, a CO2 concentration 8 exceeds the predefined concentration threshold 5 when the CO2 concentration 8 is smaller than or equal to the predefined concentration threshold 5. Only when a CO2 concentration 8 exceeds the predefined concentration threshold 5 does the controller 106 controls the wireless transmitter 104 to transmit the CO2 concentration 8. The battery unit 103 comprises a first battery 131 and a second battery 132. The second battery 132 is parallel connected to the first battery 131 while the wireless transmitter 104 transmits the CO2 concentration 8. According to an alternative embodiment, the second battery 132 is parallel connected to the first battery 131 while the wireless transmitter 104 transmits the gas concentration 2. Prior to each measurement of a gas concentration 2 by the second sensor 102, the calibration unit 107 supplies an electrical current 70 to the second sensor 102. According to an alternative embodiment, the calibration unit 107 supplies an electrical current 70 to the VOC sensor 121 prior to each measurement of a gas concentration 2 by the second sensor 102. The electrical current 70 is determined to bring the second sensor 102 at the same operational point. The electrical current 70 may be determined by the controller 106. According to an alternative embodiment, the electrical current 70 may be determined by the processor 105. According to an alternative embodiment, the electrical current 70 may be remotely programmed. The ADC 108 digitizes output values 6 of the second sensor 102. The high impedance current source 109 has an output coupled to the second sensor 102. The controller 106 controls the high impedance current source 109 to supply a current 90 to the second sensor 102 such that output values 6 of the second sensor 102 stay within a limited central interval of the operational range of the ADC 108. The processor 105 considers the current 90 when calculating the gas concentration 2 from the output values 6 of the second sensor 102. According to an alternative embodiment, the ADC 108 digitizes output values 6 of the VOC sensor 121. The high impedance current source 109 has an output coupled to the VOC sensor 121. The controller 106 controls the high impedance current source 109 to supply a current 90 to the VOC sensor 121 such that output values 7 of the VOC sensor 121 stay within a limited central interval of the operational range of the ADC 108. The processor 105 considers the current 90 when calculating the CO2 concentration 8 from the output values 7 of the VOC sensor 121. The encryption module 110 performs encryption prior to transmission by the wireless transmitter 104. For example, the encryption module 110 encrypts a gas concentration 2 and/or a CO2 concentration 8 prior to transmission. The error correction unit 120 performs error correction techniques prior to transmission by the wireless transmitter 104. The error correction unit 120 for example performs error correct techniques such as Forward Error Correction or FEC, Read Solomon Coding or RS, turbocoding, Hamming Oriented Error Correction.
[0068] The gas sensing unit 1 shown in FIG. 6 is designed such that the leakage currents are minimized, such that for example the leakage currents are as low as 2 μA in sleep mode. This further reduces the usage of the battery unit 103. Prior to the measurement of a gas concentration 2, and particularly prior to the measurement of a CO2 concentration 8, a battery level of the first battery 131 is measured in order to determine if the measurement of the gas concentration 2, and particularly the measurement of the CO2 concentration 8, can be performed.
[0069] According to an embodiment shown in FIG. 7, a housing 200 is suitable for hosting a battery-powered, wireless gas sensing unit according to any of FIGS. 1 to 6. As depicted in FIG. 7, the housing 200 may demonstrate a box-alike shape. According to alternative embodiments, the housing 200 may be a cube, a sphere, or any or suitable shape. The housing depicted in FIG. 7 for example has a height 201 of 15 millimetres, a length 202 of 50 millimetres and a width 203 of 30 millimetres. The housing 200 comprises an opening 100 adapted to allow an air circulation in the gas sensing unit 1. In other words, the opening 100 allows air to freely flow in the housing 200. The gas sensing unit 1 can then for example measure a temperature, a humidity, a gas concentration, etc. of the air in the environment of the gas sensing unit 1. According to an alternative embodiment, the opening 100 may be positioned on any surface of the housing 200, or on any corner or edge of the housing 200, even overlapping a surface of the housing 100. The opening 100 of the housing 200 depicted in FIG. 7 is half circular. According to alternative embodiments, the opening 100 is circular, square, triangular, rectangular, or can have any suitable shape. The housing 200 may comprise means for holding on for example a machine, a wall, a ceiling, etc.
[0070] Although the present invention has been illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied with various changes and modifications without departing from the scope thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. In other words, it is contemplated to cover any and all modifications, variations or equivalents that fall within the scope of the basic underlying principles and whose essential attributes are claimed in this patent application. It will furthermore be understood by the reader of this patent application that the words “comprising” or “comprise” do not exclude other elements or steps, that the words “a” or “an” do not exclude a plurality, and that a single element, such as a computer system, a processor, or another integrated unit may fulfil the functions of several means recited in the claims. Any reference signs in the claims shall not be construed as limiting the respective claims concerned. The terms “first”, “second”, third“, “a”, “b”, “c”, and the like, when used in the description or in the claims are introduced to distinguish between similar elements or steps and are not necessarily describing a sequential or chronological order. Similarly, the terms “top”, “bottom”, “over”, “under”, and the like are introduced for descriptive purposes and not necessarily to denote relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and embodiments of the invention are capable of operating according to the present invention in other sequences, or in orientations different from the one(s) described or illustrated above.
