Upgrading gas processing algorithms

AQMesh gas algorithms are in continual development through ongoing analysis of co-location datasets from all over the world. Our current production standard has now changed from V5.1 to the new V5.3. Existing users can upgrade remotely to the new algorithm, free of charge. V5.3 specifically has been developed from over 140 datasets across four continents in an extremely wide range of environments and conditions over extensive time periods.

Upgrading from V5.1 to V5.3 brings significant benefits to all users.

If users are still processing with V4.2.3 these benefits are even greater still, as they will also be benefitting from the improvements introduced with V5.1, which included improved pod-to-pod precision, “out of the box” accuracy and new QA/QC filters for erroneous data points as a result of extreme climates and sensor destabilisation.

Benefits

• Completely free-of-charge and remote upgrade
• Improved “out of the box” accuracy, including at high temperatures and pushing the limits of the pod’s operating range
• Reduction in the need for seasonal scaling

NO2 improvements:-

• Better linearity/precision at low ppb levels
• Improved performance during high temperatures

SO2 improvements:-

• Clearer detection of short-lived SO2 events

O3 improvements:-

• Better compensation for NO2 interference
• Negatives reduced / eliminated

Implications

1. Absolutely no data will be lost when changing versions
2. Pods will rebase from the point at which the version is changed
3. Scaling will automatically reset to slope = 1 and offset = 0
4. Local scaling will need to be performed again and new values applied
5. There may be a small step in the data (maximum of 5ppb for most gases) due to rebasing, not because of the version change
6. Each timestamped reading carries the version number to ensure traceability

How to upgrade

• The upgrade is a simple setting change on the server and can be carried out at your request
• It is VITAL that pods have not been moved within 48 hours prior to upgrading
• It is VITAL that pods are working in their usual monitoring environment*
• It is VITAL that pods are not turned off during the upgrade
• Users MUST give permission for this change to be made

*Unless in an environmentally controlled environment, AQMesh rebasing requires the sensors to see diurnal changes in temperature/humidity for best results.

V5.3.1

V5.3.1 is a sub-algorithm of V5.3 specifically designed to improve H2S only. All other gas sensors on V5.3.1 use the same data processing as V5.3.

H2S improvements:-

• Better linearity/precision at low ppb levels
• Clearer detection of short-lived H2S events

V5.3.2

V5.3.2 is a sub-algorithm of V5.3 specifically designed to improve CO and TVOC only. All other gas sensors on V5.3.2 use the same data processing as V5.3 & V5.3.1.

CO improvements:-

• Improved “out of the box” accuracy – true background levels are determined to reduce offset bias to a minimum and slope bias adjustment

TVOC improvements:-

• Improved resolution – ppm to ppb
• Better compensation for interferences such as temperature, humidity & CO
• New correction factors for common VOCs

Implications

1. Absolutely no data will be lost when changing versions
2. Pods will rebase from the point at which the version is changed
3. Scaling will automatically reset to slope = 1 and offset = 0
4. Local scaling will need to be performed again and new values applied
5. There may be a small step in the data (maximum of 5ppb for most gases) due to rebasing, not because of the version change
6. Each timestamped reading carries the version number to ensure traceability

How to upgrade

• The upgrade is a simple setting change on the server and can be carried out at your request
• It is VITAL that pods have not been moved within 48 hours prior to upgrading
• It is VITAL that pods are working in their usual monitoring environment*
• It is VITAL that pods are not turned off during the upgrade
• Users MUST give permission for this change to be made

*Unless in an environmentally controlled environment, AQMesh rebasing requires the sensors to see diurnal changes in temperature/humidity for best results.

By default, AQMesh upgrades the gas processing version to the latest production version when a pod is returned for service or repair unless otherwise advised by the user. This provides users with all the same benefits as upgrading in the field, without many of the implications described above. As the pods will automatically go through stabilisation and rebasing after return shipping to the user, there are almost no advantages to be gained from remaining on an out of date gas processing version compared to the accuracy improvements of upgrading to the latest processing version.