Measuring

The Live screen

Everything you need while working sits above the fold. The GPS and DEVICE blocks stay collapsed until you want them.

This is the main screen while connected. The top bar carries the buoy’s device ID on the left with the app version underneath, and Map, Logs and Disconnect on the right.

The state banner

One line, directly under the top bar, saying what the buoy is doing right now. It is colour-coded: amber while counting down, green while measuring, red for an invalid result.

Banner	What it means
Waiting for GPS fix	No usable fix yet, so a measurement cannot start
Ready — press Start to deploy	Waiting for you
Deploy countdown — N s	Grace period before logging begins
Measuring — N s left	Logging the drift
Measurement done	Finished
Done — not enough valid samples	Finished, but rejected on quality
Result ready — new measurement possible	Result stored, ready to go again
Waiting for live data…	Connected, but no packet has arrived yet

Live speed and live direction

The two large tiles show live speed in knots, with m/min underneath, and live direction in degrees with a small arrow.

These are live values, not your result

The tiles update once a second and show what the buoy sees at this instant — including while it drifts unattended, or while you carry it back to the boat. They are not the outcome of a measurement.

Your result is the LAST MEASUREMENT line directly below the tiles, and the day’s results are at the bottom of the screen.

The direction tile’s header states the convention in use, either LIVE DIRECTION (FROM-TO) or LIVE DIRECTION (FROM). See how the app words directions below.

Starting and stopping

The left button reads Start, or New measurement when a result is already stored. The right button reads Stop, or Cancel deploy during the countdown.

Each button is enabled only in the states where the buoy will accept it — Start in Ready and Result ready, Stop during the countdown and while measuring. If a button looks greyed out, the banner above explains why.

If a command does not reach the buoy the app says Command failed — connection problem?. Check the connection and try again.

GPS and DEVICE

Tap anywhere on the header row to expand a block — not just the chevron.

Two blocks, collapsed by default. Tap the header row to expand.

Block	Shows
GPS	Position, fix quality, satellites, HDOP, GPS time in local time
DEVICE	Device ID, firmware, protocol, measure window, minimum samples, HDOP limit, direction mode, start mode, device timezone

Both are read-only. They are the buoy’s own configuration, shown so you can check it without leaving the boat. To change any of it, use the buoy’s screen or its web interface.

Today’s measurements

The bottom of the screen lists the day’s valid measurements, newest first, up to ten. Each row gives the time, date, direction and speed in both knots and m/min.

The app fetches recent results from the buoy in the background, so this section fills in shortly after you connect rather than immediately.

Saved measurements

Every measurement on the buoy's SD card, newest first. Share hands the file to another app; Save writes it to your Downloads folder.

Open Logs from the Live top bar to see the measurement files on the buoy’s SD card, newest first, each with its file name and timestamp.

Control	What it does
Refresh	Re-read the list from the buoy
Share	Download the file, then hand it to any app — mail, Drive, chat
Save	Download the file and write it to Downloads/DrifterBuoy

Save needs Android 10 or newer. On older versions, use Share.

Downloads are checked with a CRC32 checksum, so a transfer that arrives damaged is reported rather than silently saved.

The list stops at 60 files

The buoy lists at most 60 entries. Older measurements stay safely on the SD card but do not appear here — take the card out to reach them.

File access pauses during a measurement

While a measurement is running, the SD card belongs to the logger and the app cannot read files from it. You will see: A measurement is running — the SD card belongs to logging. File access resumes when it finishes.

Stop the measurement or wait for it to finish, then press Refresh.

Files are CSV, one row per GPS sample, with a summary block at the end holding the averages. That footer is what the app reads to draw the map.

Times are always your phone’s times

Every timestamp the buoy produces is UTC, from GPS. Everywhere in the app, times are converted to your phone’s own timezone — the Live screen, today’s measurements, the file list, the map cards and the time-window ranges alike.

The buoy’s timezone setting does not affect the app

The buoy has its own timezone setting, and the app shows it under DEVICE for reference. It drives the buoy’s own display only. The app deliberately never applies it, because doing so on top of your phone’s own timezone would shift every time twice.

How the app words directions

The buoy can word a direction two ways, set by direction mode on the device:

Mode	Means	Example
from-to	The direction the current flows towards	146° = flowing towards the south-east
from	The direction the current comes from	The reciprocal, worded like wind

This is a choice about wording numbers, nothing more. The measurement itself is always stored as the raw GPS course — the direction the water actually moved — so the setting cannot corrupt your data.

What this means in practice:

• Numbers follow the device’s setting, and the label beside them always says which convention is in force: LIVE DIRECTION (FROM-TO), current towards, (from 326°).
• Arrows on the map always point the way the current flows, whatever the setting is. An arrow is a vector, not a label. This holds for measured arrows and for the estimated field alike.
• Changing the setting on the buoy while the app is open is picked up within a second. The numbers change their wording; the arrows do not turn around.
• Opening an older measurement uses the current wording for its numbers. The convention is a display preference rather than a property of the measurement, and the buoy does not store one per file.

If a direction looks 180° wrong

Check whether you are reading a number or an arrow. Numbers follow the setting and are labelled with it; arrows always point downstream.

Next steps

• Map — plotting the day’s measurements
• Troubleshooting
• User Guide — what the measurements mean and how the buoy records them