panormos/teamProject Panormos: GPS handbook
The project will have at least 4x GPSes:-
- 2x Garmin Monterra
- 2x Garmin eTrex 20
Garmin Monterra (Data logger and GPS)
The Garmin machines are used as both advanced GPS and data logging devices. They run a version of Android OS which is familiar from many modern smartphones. Currently, the Monterras use Android 4.1 which is older than that used in new phones (4.4 KitKat or 5 Lollipop are now typical, as of Jul 2015), but is still stable version and can run a wide range of modern software required for the survey.
Since the android smartphone user interface is increasingly familiar to most users, a detailed explanation is not required here. It is worth noting, however, for those less familiar with Android, that one should take care with accidentally moving icons around on the ‘home screens’.
Gear
- Monterra
- USB cable (charging/data transfer)
- USB charger
- Spare battery
- Lanyard (the hook attached to device which allows you to hang it from a belt etc.)
Basic usage
Power on/wake+sleep: the power button is on the right of the screen. To switch power on or off this must be held down for a few seconds. To save battery the screen switched off automatically after a short period of inactivity. The same button is therefore used to wake the screen (and send the screen to sleep) when the device is one.
Charging: charging is done by a standard mini-USB cable and 5-volt charger. The port is hidden under a rubber flap on the back of the device.
Batteries: the device uses a rechargeable Li-ion battery which is standard in many smartphones today. This should last a full day of normal usage, but must be charged daily. Batteries can be replaced used the twist-lock on the back. Users should ensure that spare batteries are also charged ahead of time. In an emergency, 3 standard AA batteries can be used instead to replace the Li-ion battery.
Battery life: GPS and Wifi: the GPS module and the Wifi module consume battery power quite quickly. It is therefore very important to switch the Wifi OFF when in the field to maximise battery. When back at base, the device should be plugged into charger and wifi should be switched on to ensure automatic backup of collected data. Wifi can be switched on/off from the Wifi 'Toggle button’ on the home screen, or in 'Settings’.
Battery life: Screen: the most battery intensive part of the device is the screen. Try to avoid keeping screen brightness higher than necessary.
GPS start up time: the GPS can take a few minutes to get a lock on satellites.
Apps: the apps most likely to be of usage have been placed on the primary home screen. Other apps can be found by clicking on the circle with 6 dots).
App Usage: Map
This Garmin app is a multi-purpose navigation app. It will have a custom satellite image (WorldView-2 image) of the survey area and Guide points registered as POIs. Waypoints can be added (and will be shown in this map) with the standard Garmin 'Mark Waypoint’ app.
App Usage: AlpineQuest
This is a more sophisticated multi-purpose map app. It can download tiles from various online mapping services (including Bing, Gmaps and Yahoo) to allow a range of possible base maps, display POIs, take way-points as well as 'photo way points’.
Garmin Map and AlpineQuest can both be used to mark points of interest, view an area from above and establish that the survey team is in the right place to start extensive field walking, based on guide points. Only testing will reveal which is the better 'in-the-field’ tool.
App Usage: ODK Collect
This app allows the user to enter standardised data into pre-designed forms, as 'born-digital’ (i.e. in a way which can skip paper-forms and unnecessary digitisation).
Panormos forms will be pre-installed on the device, though the latest version (if changes are made), can be downloaded by using the 'Get Blank Form’ menu item.
At recording time, new forms must be opened by choosing 'Fill Blank Form’:
Tracts: when each tract is finished, the user will need to open a new tract form. Questions are designed to create the minimal amount of input required to provide full information. Photos and GPS points can also be (optionally) included in each form.
POI: points of interest (sometimes 'sites’, sometimes other feature of interest) should be entered at the 'centre point’ to include the best GPS point included. Photos can (optionally) be taken with the form.
Automatic data transfer. Data collected with ODK will be automatically uploaded to the central (ODK Aggregate) database server for Panormos when the Monterra device is reconnected to the internet via Wifi. (It is therefore important that the devices are connected nightly to the internet whilst charging).
App Usage: Satellite
This app allows you to see the number of satellites that the device can see and is using to calculate position. It also gives the degree of precision of the current GPS read-out (in metres). Accuracy/precision of 3-5m is good, above 10-15m is not ideal for taking points unless a very large area is indicated. Areas with clear skies will give better reception. Buildings, electrical wires and trees will interfere with the signal.
App Usage: Camera
Garmin eTrex 20 (GPS)
This is a basic GPS model, but very compact and of sufficient degree of accuracy for field walking.
The device will be prepared with a satellite basemap (Worldview-2 image) of the survey area for navigation, and the guide points will be uploaded as POIs.
Batteries: This device relies on 2 AA batteries, rechargeable on non-rechargeable can be used. With average field walking use, the device is likely to last 1-3 days on one set of full batteries depending on battery capacity. Spares should always be carried, and rechargeables will probably need to be charged nightly.