Tutorials

Instrument Overview

In this video, Christoph gives an overview of the components that make up a NOVAC scanning DOAS instrument. The video discusses a 3^rd generation instrument which uses a MOXA embedded computer for data acquisition.

Field Access

This video describes how users can connect to a NOVAC scanning DOAS instrument in the field. This allows testing/troubleshooting as well as manual downloading of collected data.

Common Failures

In this video, Christoph describes three common modes of failure that can occur with NOVAC scanning DOAS instruments: (1) Failure of the power supply, (2) Failure of the ‘Octopus’ electronics box, and (3) Failure of the scanner due to corrupt configuration or displaced end switch.

NOVAC Checks From Observatory

This video describes a few simple instrument checks that can be performed from any computer with access to the NOVAC scanning DOAS station, e.g. from the volcano observatory. Viewers learn how to identify whether the scanner is stepping, whether the spectrometer communication is working, whether spectra are being saved in the station, and what the exposure time of the measurements is.

SD2000 Serial Test

This video describes a simple way to check whether an SD2000 spectrometer is still working. Christoph  powers the spectrometer using a USB cable, then communicates with it over a serial connection just as the NOVAC embedded computer would also do.

Troubleshooting the Scanner End Switch

In this video, we troubleshoot a common failure with the NOVAC scanners: a loose or incorrectly positioned end switch. When working properly, the end switch defines the reference position of the scanner and tells the instrument which way is up. Problems with the end switch can cause the scanner to rotate indefinitely without the measurement ever starting, or make the instrument scan the ground rather than the sky.

Calibrating a new Avantes AvaSpec Mini with Mobile DOAS

The latest version of Mobile DOAS has a feature that automatically creates reference cross sections at the beginning of a measurement. In this short video, we use this feature to calibrate a new Avantes AvaSpec Mini spectrometer and generate reference cross sections for later use.

Reference guides for NOVAC and MobileDOAS instrument preparation, calibration, and troubleshooting

In addition to the videos above, Allan and Christoph have written the following guides to provide details for preparing both NOVAC and MobileDOAS instruments and for addressing some common issues with accessing, calibrating, and troubleshooting the instruments. These reference guides can be printed out and brought to the field for use at instrument sites and during measurements.

NOVAC reference guide: This reference guide provides instructions for preparing and configuring NOVAC instruments, scanners, and on-board computers. This document also contains additional guides for A) connecting to the on-board NOVAC computer via ethernet and setting network IP and configuration files, B) manually downloading and viewing NOVAC data, C) calibrating the NOVAC spectrometer, D) accessing and tightening the scanner reference switch, and E) a photo guide for troubleshooting scanner issues, including reference switch tightening and motor alignment issues:

MobileDOAS reference guide: This tutorial provides details on A) configuring a computer for MobileDOAS use, B) calibrating the spectrometer and enabling automatic calibrations, C) assembling the MobileDOAS telescope, and D) wiring the UPS connection for the GPS:

MobileDOAS quickstart guide: A 2-page quick reference guide for conducting MobileDOAS measurements:

And, of course, don’t forget to look at the full NOVAC and MobileDOAS user manuals (within NOVAC github page) for more thorough information:

NOVAC user manual: https://github.com/NOVACProject/NOVACProgram/tree/master/doc

MobileDOAS manual: https://github.com/NOVACProject/MobileDOAS/tree/master/doc

Please forward any questions you might have about these guides (or suggestions for other information) to ckern@usgs.gov and alerner@usgs.gov. Thanks!