Field

This disclosure relates to a gas detector, for detecting carbon dioxide or other gases, that is suitable for use in a container or vehicle. In particular, but not exclusively, the disclosure relates to alerting the presence of people in an enclosed space such as a vehicle or shipping/haulage container. Background

Current guidance from the United Kingdom Home Office requires haulage firms and drivers to take adequate steps to avoid stowaways gaining access to their vehicles. In particular, where hauliers are found entering the United Kingdom with illegal migrants on board, they are liable for civil penalties. This requirement can lead to practical and financial burdens on haulage firms and their drivers, since additional precautions may be needed, beyond the security measures in force at ports and border crossings.

Additionally, the presence of stowaways in vehicles and containers can result in damage of goods being transported. Summary

According to a first aspect, a portable gas detector includes a sensor configured to determine an amount of one or more gases in an enclosed space and to generate an alert in response to an alarm condition, a location module, device or chip configured to determine a location of the gas detector, and a communication module, device or chip configured to, in response to the generation of the alert, transmit the alert and the location to a base station.

The sensor may comprise a light source, a light detector arranged to receive light from the light source, where the received light has passed through gases from the enclosed space and a spectrum analyser configured to analyse an absorption spectrum of the received light to determine the amount of the one or more gases in the enclosed space. In some embodiments, the light source may be adjustable to allow a wavelength of the light from the light source to be varied, to facilitate testing for different types of gases. The one or more gases may include carbon dioxide. As carbon dioxide is present in exhaled breath, testing for that gas may be used to detect the presence of people in the enclosed space. Additionally, or alternatively, the one or more gases may include oxygen.

The alarm condition may be met when the amount of the one or more gases exceeds a threshold, or when a rate of change of the amount of the one or more gases exceeds a threshold. In some embodiments, the alarm condition may be met when a rate of change of a first one of the one or more gases exceeds a first threshold and a rate of change of a second one of the one or more gases exceeds a second threshold. For example, in an embodiment for detecting the presence of people, an alarm condition may be met when a carbon dioxide level is increasing, or exceeds a give threshold and an oxygen level is determined to be decreasing. The portable gas detector may be configured to wake periodically from a sleep state to perform determining the amount of the one or more gases. Such a configuration reduces power consumption and can, therefore, extend the useful lifetime of a battery that supplies power to the detector. The portable gas detector may, optionally, include a proximity sensor, configured to detect a presence of a person within a predetermined distance of the detector. This can be used to detect potential tampering with the detector.

This aspect also provides a container comprising a portable gas detector as described above, wherein the enclosed space is inside the container.

This aspect also provides a vehicle comprising a portable gas detector as described above, wherein the enclosed space is inside the vehicle. Such a container or vehicle may include a repeater mounted on the outside of the container or vehicle, configured to receive data transmitted from the communications module, device or chip and to forward the data to the base station. By using a wireless link between the detector and the repeater, the need for a wired connection between the detector and an antenna outside the vehicle may be avoided. This may facilitate installation of the detector, since apertures for the wires in the walls of the container or vehicle might not be needed. This may also assist in concealing the location of the detector and may, therefore, reduce the likelihood of tampering.

Where the detector is located in a vehicle, an alarm device may be arranged to provide an audio and/ or visual alarm to a driver of the vehicle. Alternatively, or additionally, the detector may be configured to transmit the alert signal and the location to the police or to a government authority.

According to a second aspect of the disclosure there is provided a gas detector for alerting the presence of people in an enclosed space, the gas detector comprising:

a sensor configured to determine concentrations of oxygen and carbon dioxide gases in the enclosed space and to generate an alert in response to an alarm condition comprising a rate of increase in concentration of carbon dioxide gas exceeding a first threshold and a rate of decrease in concentration of oxygen gas exceeding a second threshold;

a location module, device or chip configured to determine a location of the gas detector; and

a communication module, device or chip configured to, in response to the generation of the alert, transmit the alert and the location to a base station.

The sensor may comprise:

a light source; and

a light detector arranged to receive light from the light source, where the received light has passed through gases from the enclosed space; and

a spectrum analyser configured to analyse an absorption spectrum of the received light to determine the concentration of the oxygen and carbon dioxide gases in the enclosed space.

The light source may be adjustable to allow a wavelength of the light from the light source to be varied.

The gas detector may be configured to wake periodically from a sleep state to determine the concentrations of the oxygen and carbon dioxide gases.

The gas detector may comprise a proximity sensor, configured to detect a presence of a person within a predetermined distance of the detector. Another aspect provides a container comprising a gas detector as above, wherein the enclosed space is inside the container. The container may comprise a repeater mounted outside the container, configured to receive data transmitted from the communications module, device or chip and to forward the data to the base station, wherein the communications module, device or chip is configured for wireless communication with the repeater. An additional aspect provides a vehicle comprising a gas detector as above, wherein the enclosed space is inside the vehicle.

The vehicle may comprise a repeater mounted outside the enclosed space, configured to receive data transmitted from the wireless communications module, device or chip and to re-transmit the data to the base station, wherein the communications module, device or chip is configured for wireless communication with the repeater.

The vehicle may comprise an alarm device arranged to provide an audio and/ or visual alarm to a driver of the vehicle.

The wireless communications module, device or chip may be configured to transmit the alert signal and the location to a government authority.

Another aspect of the disclosure provides a method of alerting the presence of people in an enclosed space, the method comprising:

using a gas detector, determining concentrations of oxygen and carbon dioxide gases in the enclosed space and generating an alert in response to an alarm condition comprising a rate of increase in concentration of carbon dioxide gas exceeding a first threshold and a rate of decrease in concentration of oxygen gas exceeding a second threshold;

determining a location of the gas detector; and

in response to the generation of the alert, transmitting the alert and the location to a base station. Determining the concentrations of oxygen and carbon dioxide gases may comprise: detecting light using a light detector arranged to receive light from a light source, where the received light has passed through gases from the enclosed space; and analysing an absorption spectrum of the received light to determine the concentrations of oxygen and carbon dioxide in the enclosed space.

According to another aspect, a method of detecting the presence of people in a container or vehicle includes, using a gas detector, determining an amount of one or more gases in an enclosed space and to generate an alert in response to an alarm condition, wherein the one or more gases are indicative of the presence of people, determining a location of the gas detector and, in response to the generation of the alert, transmitting the alert and the location to a base station.

Determining the amount of the one or more gases may include detecting light using a light detector arranged to receive light from a light source, where the received light has passed through gases from the enclosed space, and analysing an absorption spectrum of the received light to determine the amount of the one or more gases in the enclosed space. Optionally, the method may further include adjusting the light source to change a wavelength band of light emitted by the light source and analysing the absorption spectrum of the received light to determine the amount of another gas in the enclosed space.

According to yet another aspect, a method of detecting of the presence of explosives includes, using a gas detector, determining an amount of one or more gases in an enclosed space and to generate an alert in response to an alarm condition, wherein the one or more gases are indicative of the presence of explosives, determining a location of the gas detector and, in response to the generation of the alert, transmitting the alert and the location to a base station.

According to a further aspect, a method of monitoring the condition of perishable items includes, using a gas detector, determining an amount of one or more gases in the container and to generate an alert in response to an alarm condition, wherein the one or more gases are indicative of deterioration of the perishable items, determining a location of the gas detector and, in response to the generation of the alert, transmitting the alert and the location to a base station. In one example, the perishable items are food items and the one or more gases are indicative of rotting of the food items.

Brief description of the drawings

Example embodiments will now be described with reference to the accompanying drawings, of which:

Figure ι depicts a portable gas detector in accordance with an embodiment;

Figure 2 is a block diagram of the portable gas detector of Figure l;

Figure 3 depicts part of a sensor in the portable gas detector of Figure 1;

Figure 4 is a flowchart of a method of operating the portable gas detector of Figure 1, according to an embodiment;

Figure 5 depicts a vehicle according to another embodiment; and

Figure 6 depicts a container according to yet another embodiment.

Detailed description

In brief, this specification discloses a gas detector that is configured for alerting the presence of people in an enclosed space. A sensor is configured to determine concentrations of oxygen and carbon dioxide gases in the enclosed space. If it is determined that a condition of a rate of increase in concentration of carbon dioxide gas exceeding a first threshold and a rate of decrease in concentration of oxygen gas exceeding a second threshold is present, an alert is generated. A location module, device or chip is configured to determine a location of the gas detector, and a communication module, device or chip is configured to, in response to the generation of the alert, transmit the alert and the location to a base station.

Figures 1 and 2 depict a portable gas detector 1 according to an embodiment. In this embodiment, the portable gas detector 1 includes a housing 2, which may be mounted on a wall of an enclosed space within a container, a vehicle or other structure. The portable gas detector 1 may also be removable from the wall, to allow it to be easily redeployed in different locations.

The housing includes a port 3 through which ambient air can enter for detection of gases by a gas sensor 4. In this particular example, the detector 1 is powered by a rechargeable battery 5, such as a lithium-polymer (LiPo) battery, and is equipped with a charging port 6 for receiving a connector (not shown) for receiving power from a power source (not shown) to charge the battery 5 via charging circuitry 7, and an indicator 8 for, such as a light emitting diode (LED), for indicating a status of the battery 5 at least during charging.

The detector 1 also includes a location module, device or chip 9, such as a Global Positioning Systems (GPS) unit or a Galileo unit, an associated antenna 10, and a communications module, device or chip 11, such as a Global System for Mobile (GSM) unit or a Universal Mobile Telecommunications Service (UMTS) unit, and a

corresponding antenna 12. In this particular embodiment, the antennas 10, 12 are located within the housing 2 of the portable gas detector 1. In other embodiments, the antennas 10, 12 may be provided external to the housing 2. Optionally, the portable gas detector 1 may include one or more additional

communications units (not shown), such as a Wi-Fi unit or Bluetooth® unit.

In this particular embodiment, the portable gas detector 1 also includes a proximity sensor 13. The proximity sensor 13 may detect movement of a person or object in the vicinity of the portable gas detector 1, for example, by emitting infra-red radiation from a LED (not shown) through an aperture 14 in the housing 1, detecting reflections of the infra-red radiation returned through the aperture 14 using a photodetector (not shown) and determining whether there has been a change in the reflections arising from such movement. The proximity sensor 13 can, therefore, be used to generate an alarm in the event of a person tampering with the portable gas detector 1.

A controller 15 is arranged to control operation of the sensors 4, 13, location module, device or chip 9, communication module, device or chip 11 and charging circuitry 7. The controller 15 may be in the form of one or a plurality of processors, such as a microprocessor, controlled by software and/ or firmware stored in one or more memory units 16.

To conserve battery power, the controller 15 may be configured to keep one or more of the sensor 4, location module, device or chip 9 and communication module, device or chip 11 in a "sleep" mode, and to "wake" those components periodically when a test for a gas in the enclosed space is required. For example, the controller 15 may be configured to wake those components to perform a test every 5, 10 or 20 minutes. A suitable time period may be chosen according to the purpose of the tests.

The sensor 4 includes a light source 17, a light detector 18 and a spectrum analyser 19. Although the spectrum analyser 19 is depicted in Figure 2 as being separate from the controller 15, the controller 15 may be used to perform the functions of the spectrum analyser 19 described hereinbelow.

As shown in Figure 3, the light source 17 and a light detector 18 are arranged so that light emitted from the light source 17 passes through ambient air that has entered a cell chamber 20 in the housing 2 of the portable gas detector 1, via the port 3.

In this example, the light source 17 includes a plurality of LEDs, configured to emit light within a waveband suitable for detecting a predetermined gas using one or more distinctive features in the absorption spectrum of that gas. For example, the absorption spectrum of carbon dioxide shows significant absorption of light between 4200 nm and 4300 nm. Where the portable gas detector 1 is configured to detect carbon dioxide, the light source 17 may include LEDs emitting light in a waveband encompassing that range. Examples of sensing module, device or chips including a light source 17 and light detector 18 suitable for detecting carbon dioxide include flow-through sensors such as the Telaire® 6613 CO2 module, device or chip and the Telaire® 6713 Series CO2 module, device or chip, manufactured by Amphenol Advanced Sensors.

In some embodiments, the controller 15 is configured to adjust the wavelength of the light emitted by the light source 17, so that the portable gas detector 1 can be used to detect, and estimate the amount of, different gases. A command may be sent to the controller 15 to adjust the wavelength of the light via the communications module, device or chip 11 or, where provided, the other communications module, device or chip (not shown). The controller 15 could then control the light source 17 to use selected ones of the plurality of LEDs 21 so that light in a suitable waveband for detecting another gas is emitted. The spectrum analyser 19 and the controller 15 may also be reconfigured accordingly, for example, by changing algorithms used by the spectrum analyser 19 and/ or controller 15 to estimate the amount of a gas or by configuring the spectrum analyser 19 and/or controller 15 to utilise a look-up table corresponding to the other gas. Alternatively, multiple gases could be monitored in an enclosed space by providing a plurality of portable gas detectors 1, configured to detect different gases.

A method of detecting a gas using the portable gas detector 1 will now be described, with reference to Figure 4.

Starting at S4.0, the controller 15 wakes the sensor 4, location module, device or chip 9 and communications module, device or chip 11 from a sleep state (S4.1). If a warm-up period is required for the sensor 4, the controller 15 waits until the warm-up period has elapsed before proceeding further.

To test for the presence of a gas, light is emitted by the light source 17 (S4.2) and received by the light detector, after having passed through the chamber 20. The spectrum of the light received by the light detector 18 are then analysed by the spectrum analyser 19 (S4.3). For example, in this particular embodiment, the spectrum analyser 19 is configured to detect significant absorption features in the spectrum of the light received by the light detector 18, determine the wavelengths or frequencies corresponding to those absorption features and output data regarding the wavelengths and the magnitudes of those absorption features to the controller 15.

The controller 15 receives the data output by the spectrum analyser 19 and, based on the wavelengths of the absorption features, identifies whether a particular gas is present and estimates the amount of that gas in the enclosed space (S4.4). The controller 15 may use one or more look up tables stored in the memory unit 16 to obtain an estimated the amount based on the received magnitudes. In another embodiment, the controller 15 uses an algorithm corresponding to the gas being detected to determine the amount of that gas that is present in the enclosed space. The controller 15 then determines whether an alarm condition has been met (S4.5). The alarm condition may be met if the estimated amount of the gas exceeds a predetermined threshold. Table 1 is a list of carbon dioxide concentrations, where a normal atmospheric level of CO2 is presumed, an example amount of excess CO2 needed to trigger an alarm condition and example time intervals needed for the alarm condition to be triggered where there is one occupant of the enclosed space. When calculating the excess CO2 amount for an alarm condition and the example time intervals in Table 1, a volume of the enclosed space of 1000 cubic feet (approximately 28.32 cubic metres) and a rate of production of carbon dioxide for a single person in an enclosed space of 1.7 ft ³ /hr (approximately 0.05 ms/hr) were assumed.

Table 1

Table 2 is a list of carbon dioxide concentrations, a rate of production of carbon dioxide for five people in an enclosed space of 1000 cubic feet (approximately 28.32 cubic metres), an example amount of excess CO2 needed to trigger an alarm condition and a length of time needed for the alarm condition to be triggered where there are five occupants of the enclosed space. When calculating the excess CO2 amount for an alarm condition and the example time intervals in Table 2, a volume of the enclosed space of looo cubic feet (approximately 28.32 cubic metres) and a rate of production of carbon dioxide for each person in an enclosed space of 1.7 fts/hr (approximately 0.05 ms/hr) were assumed, giving a total rate of production of carbon dioxide for five people in an enclosed space of 8.5 ft ³ /hr (approximately 0.25 ms/hr).

Table 2

Alternatively, or additionally, the alarm condition may depend on a rate of change of an amount of the gas being detected. For example, an alarm may be triggered in response to a significant increase in the amount or concentration of carbon dioxide in a given period of time. For example, to trigger an alarm when a single person is detected in an enclosed space of 1000 cubic feet (approximately 28.3 cubic metres), the alarm condition may be defined as an increase in the amount of carbon dioxide of 0.3 cubic feet (approximately 0.008 cubic metres) or greater, over a time period of ten minutes.

The alarm condition may include multiple criteria. For example, the alarm condition may be defined based on an amount of gas exceeding a predetermined threshold in addition to a rate of change exceeding a second predetermined threshold.

In embodiments where the light source 17 is adjustable to vary a wavelength at which light is emitted, or where multiple portable gas detectors 1 are provided, the alarm condition may depend on the amounts and/or the rates of change of more than one gas in the enclosed space. Where the portable gas detector 1 is used to detect the presence of people, an alarm condition may be met when it is determined that the amount of carbon dioxide in the enclosed space is increasing at a significant rate while the amount of oxygen in the enclosed space is decreasing.

If it is determined that an alarm condition has been met (S4.5), then a location of the portable gas detector 1 is obtained using the location module, device or chip 9 (S4.6) and an alert is generated (S4.7). The alert is transmitted via the communications module, device or chip 11 to a base station or other external apparatus. For example, the alert may be transmitted, via a cellular telephone network, to a company that owns a container or vehicle in which the enclosed space is located. Alternatively, or additionally, the alert may be transmitted to a government authority. Where the enclosed space is in a vehicle, the alert may be transmitted to a driver of the vehicle. If the alarm condition was not met (S4.5) or following the generation of an alert (S4.7), the controller 15 determines whether the sensor 4 should be adjusted to monitor a different gas (S4.8). This determination may be based on whether a command to adjust the sensor 4 has been received. Alternatively, the determination may be based on an algorithm performed by the controller 15, for example, to switch periodically between detection of different gases and/or to switch to another gas in response to an alarm condition or a threshold being met by the gas currently being detected.

If the sensor is to be adjusted (S4.8), then the controller 15 changes the way it controls the light source 17, so that a different selection of LEDs 21 are illuminated in subsequent tests (S4.9). The controller 15 also makes adjustments to the algorithms it uses to analyse test results and may also control the spectrum analyser 19 so that it makes adjustments to its processing of the output from the light detector 18 (S4.10). Another test is then made to detect and estimate the amount of another gas in the enclosed space (S4.2 to S4.8). If adjustment of the sensor 4 is not required (S4.8), and monitoring of the enclosed space is to continue (s4.11), then the controller 15 places the sensor 4, location module, device or chip 9 and communications module, device or chip 11 into a sleep state (S4.12) for a time period T, after which the controller 14 wakes those components (S4.1) to perform another test.

If monitoring of the enclosed space has been completed (s4.11), for example, if the portable gas detector 1 is being powered down or if a command has been received by the controller 15 to stop monitoring, the process ends (S4.13). Figure 5 depicts an example of a vehicle 22 according to an embodiment, in which the portable gas detector 1 is used to monitor an enclosed space. In this particular example, the vehicle 22 is a lorry and the enclosed space is a container portion 23 of the lorry. A portable gas detector 1 is located at a relatively low position in the container portion 23, to facilitate carbon dioxide detection.

A repeater 24 is provided in the vehicle 22, to transmit and receive signals to and from the communications module, device or chip 11. The provision of the repeater 24 means that the communications module, device or chip 11 need only transmit data over relatively small distances, reducing the power consumption of the portable gas detector 1. In particular, where wireless signals are not easily transmitted through the walls of the container portion 23, for example, where the container portion 23 is a refrigerated section with thick metallic walls, then the use of a repeater 24 may also improve reliability of communications. In addition, the use of the repeater 24 can avoid the need for a wired connection to an antenna outside the container portion 23. As well as allowing the portable gas detector 1 to be self-contained, the provision of such a wireless connection can make the portable gas detector 1 relatively easy to install and remove, facilitating use of the same portable gas detector 1 in different vehicles. In addition, the portable gas detector 1 can be more easily concealed, since its location would not be indicated by the presence of wires leading to the outside of the container portion 23. The communications module, device or chip 11 and/or the other communications module, device or chip, where provided, may be configured to transmit data to a device 25 in a driver's section 26 of the vehicle 22 via a cellular network or, where provided for, a Wi-Fi connection, a Bluetooth® connection or similar. For example, the device 25 may be a modem that may be used in place of, or in addition to, the repeater 24. In one embodiment, the device 25 is a mobile telephone carried by the driver, configured to notify the driver of an alert and to transmit the alert and the location information to another destination via a mobile telephone network. In another embodiment, the device 25 simply notifies the driver of an alert by providing a visual and/or audio alarm.

Depending on the purpose of the gas detection, the alert and the current location of the vehicle 22 may be transmitted to the driver and/or to another destination. For example, where the portable gas detector 1 is used to detect the unauthorised presence of stowaways, based on carbon dioxide and/ or oxygen monitoring, the alert and current location of the vehicle may be transmitted to an authority, such as the police and/ or an immigration authority.

Figure 6 depicts an example of a container 27 equipped with a portable gas detector 28 according to another embodiment. The portable gas detector 28 and its operation is similar to that described above with reference to Figures 1 to 4. However, in this particular embodiment, the housing of the portable gas detector 28 does not contain the antennas associated with the location module, device or chip 9 and communications module, device or chip 11. Instead, external antennas 29, 30 are provided for the location module, device or chip 9 and the communications module, device or chip 11 on the outside of the container 27. The location module, device or chip 9 and the communications module, device or chip 11 are connected to their respective antennas 29, 30 via wired connections 31, 32. The portable gas detector 28 may be configured to provide alerts to one or more destinations, as described above in the examples discussed with reference to Figure 5.

The specific embodiments are intended to provide examples of ways in which the present teaching may be implemented and are not intended to further limit the scope of the accompanying claims. In particular, it is noted that the portable gas detector and the gas detection methods may be used to detect gases other than carbon dioxide and/ or oxygen, or other combinations of gases. While the example shown in Figure 5 relates to a lorry having a self-contained portable gas detector 1 and Figure 6 depicts a container 27 having a portable gas detector 28 with external antennas 29, it is noted that such portable gas detectors may be used in other types of vehicles and structures. For example, a portable gas detector maybe used to monitor a cargo hold of a ship or an aeroplane, or the trunk of a car. Also, in other embodiments, wired connections 31, 32 and external antennas 29, 30 may be used for portable gas sensors 28 in vehicles, while a structure such as a container may be provided with a self-contained portable gas detector 1.

Also, the step of determining and/ or transmitting the location is optional and may be omitted.

In addition, there are other instances where it is beneficial to analyse other conditions within a lorry load or container. In some embodiments, the portable gas detector 1 is used to detect deterioration of perishable items, such as food. Such deterioration may be detected by monitoring one or more of carbon dioxide, methane and hydrogen sulphide levels in the container portion 23. In these embodiments, the alert maybe transmitted to a company that owns the vehicle 22 and/or the items.

In other embodiments, the portable gas detector 1 is used to detect the presence of explosives in the contents of a lorry or container. In these embodiments, the alert and current location of the vehicle may be transmitted to the driver, a company that owns the vehicle and/or cargo and the police.