Preparation, operation and deployment.

What Tesel is

Tesel is a situational awareness tool for teams. It brings together on one shared map every member's position, what has been marked on the ground (sectors, meeting points, hazards), the team's messages and its alerts. If someone needs help, they press SOS and the whole team knows at once, with their position.

With internet it works like any messaging app. Without internet it keeps working in two ways: with pocket radios that pass messages to each other, or through a command post, a computer with its own Wi-Fi in the area of operations.

Before: get the team ready

An emergency is no time to learn a new tool. Set aside half an hour on a quiet day.

Everyone

1. Open tesel.eu/app in your phone's browser and type your name. No email, phone number or password needed.
2. Add it to your home screen. On Android, with Chrome: menu ⋮ → “Add to Home screen”. On iPhone, with Safari: Share button → “Add to Home Screen”. It then opens like an app and works offline.
3. Download the map of your area: “More” → “Offline maps”, move the map to your area and tap “Download visible area”. In Spain you can also download the topographic and satellite maps. Do it on Wi-Fi, as it takes space.

The coordinator

1. Create the group in “Groups” → “Create a group”. Whoever creates it is its coordinator: they can invite others and send alerts.
2. Tap “Invite” and share the link, or let people scan the QR code. Whoever has the invitation joins the group, so share it only with those who belong.
3. Mark the operation area: “Add” → “Area”, draw it and choose “Operation area”. Each member of the group will be offered “Download” to have its map without a connection.
4. If you are going to use radios, set them up in advance (see Radios).

The whole team

• Agree on a simple plan: a meeting point, who coordinates and what to do without coverage.
• Run a drill: send a message, send a test SOS and cancel it, and if you have radios, repeat it with phones in airplane mode and Bluetooth on.
• Repeat the drill now and then, with charged batteries.
• To learn the app on your own, tap “Groups” → “Practise with a simulated group”. Four simulated teammates move around you, mark what they find, write in the chat and, after two minutes, one of them calls for help with an SOS. They answer if you call the roll or send your own SOS. It all happens on your phone: nothing leaves it. The practice ends with “End practice” or when you close the app.

During an operation

At the bottom are the SOS button and five buttons: Me, Add, Chat, Tasks and More. For everything else, touch the map: press and hold a point, or tap a marker or a member, and you will see what you can do there.

• Share your position in “Me”, with three buttons: “Share”, “Pause” (the group sees where you were) and “Hide”. “Me” also tells you your coordinates and how precise your GPS is: green, good; orange, fair; red, poor.
• Write to the group with the “Chat” button. Keep messages short and clear: over radio they cost less and arrive sooner.
• Mark what matters with “Add”: a marker (a meeting point, a hazard) or a zone (a sector). The whole group sees it at once.
• Share out the work with “Tasks”: “Check the warehouse”, “Bring water to the post”. Only the text is needed; if you like, say who it is for and give it a place by pressing and holding the map → “Task here”. Anyone can add, start and finish tasks, and a number on the button tells you how many are yours. Use them the way that suits your team: for everything, for what matters, or not at all.
• If you need help, press SOS, choose what is happening and send it. It carries your position. When someone sees it they tap “Acknowledge” and you will know. If it is no longer needed, cancel it.
• If you see someone else's SOS, tap “Acknowledge” so they know the group has seen it.
• Coordinators can tap “Send as alert” in the chat: the message stays on everyone’s screen until each person acknowledges it. On Android the phone also vibrates.
• Roll call. The coordinator taps “Call the roll” in the chat and each person gets “Is everyone well?” with two buttons: “I’m well” or “I need help”, which opens the SOS. Whoever called it sees how many have answered and who has not. It works over radio too.

Finding your way

The tools in this section work on the phone itself, with or without a group, and with no connection.

• Where you are. The target button under the zoom shows you on the map and keeps the map centred on you. Move the map with your finger and it stops following; press it again to centre. The GPS is only used while something needs it: sharing your position, this button or guidance.
• Coordinates. Press and hold a point of the map (right click on a computer) to see its coordinates, ready to copy. The format (degrees, DMS, UTM or MGRS) is chosen in the drop-down next to them and remembered. If someone reads you coordinates, type them in “More” → “Go to a coordinate” as you were given them and the app finds them on the map.
• Getting somewhere. A point of the map, a marker or a team member shows how far it is from you and in which direction. With “Guide me”, a card at the top shows the distance and an arrow pointing the way, and a dotted line joins you to the destination. When the destination is a member, it moves with them. While guiding you, the screen stays on.
• Measuring. “More” → “Measure distances”, or “Measure from here” on a point: tap the map point by point to see the total distance and, from three points, the area they enclose. Zones drawn on the map also show their area.
• Map type, trails and layers. With the layers button under the zoom you choose the map by tapping its picture: streets, topographic (contour lines and paths) or satellite (aerial photographs). The last two come from Spain’s Instituto Geográfico Nacional and cover Spain only. Each member leaves a line behind with where they have been in the last hours; with the switches in the same panel you hide members, trails, markers or tasks to see better. Your own position and SOS calls are always shown. With “Relief” on, the map shades hills and valleys and, next to the distance to a place, you see how much the straight way climbs and descends, and its steepest stretch.
• Services. The map marks health centres and hospitals, pharmacies, fire stations, police, helipads, town halls and fuel stations with round icons: the large ones from afar, the rest when zoomed in to street level. Tap one for its name and to be guided there. They come from OpenStreetMap with the map, so they are also there offline in areas downloaded with “Streets” detail. In some villages the map may be incomplete.
• Weather warnings. Official yellow, orange and red warnings (AEMET in Spain, IPMA in Portugal, through MeteoAlarm) tint their region on the map. If your location is on and you are inside one, a card at the top says what it warns of and until when; a long press on any point shows the warnings there. The app keeps them, so without coverage you still see the last ones it received. Hide them with “Weather warnings” in the map layers.
• Who you reach by radio. Tap a member on the map for their details: when something of theirs last reached you by radio, through the server or through the command post. In the group’s list of members, a mast marks those who reach you by radio: from their own radio or passed on by another member.
• Screen on. In “More” → “Screen always on”: with the switch green, the screen does not turn off while Tesel is open. It uses more battery.

Afterwards: the diary

“More” → “Operation diary” tells everything that has happened in the group, in order: who joined, the messages, alerts and SOS calls, who received them, and every marker or zone added, changed or deleted. “Download the diary” gives it to you as a text file for the report, with coordinates in your format.

In the same panel you can save a copy of the group’s log: all its events, encrypted, readable only by members. Loaded on another device of the group, it brings that device whatever it is missing. Use it as a backup, or to carry to the command post, on a memory stick, what a phone lived through by radio only.

When there is no internet

First of all: you do not need to change anything in the app. Tesel uses whatever link there is. What you write offline is kept and goes out as soon as there is one.

At the top, next to the logo, Tesel always says what it is connected through: “WiFi”, “4G/5G” or “LoRa”, or several at once (“WiFi · LoRa”), with a green dot; “Connecting…” with an orange dot, or “No connection” with a red one. Where the phone does not say whether it uses Wi-Fi or mobile data (on iPhone, for instance), it shows “WiFi/5G”. Tap it for a card per connection.

If you have a radio

Tap the connection indicator at the top, and in “Connections” tap “Connect radio”. From then on your messages, position and SOS go out by radio and the group's reach you, and the indicator says “LoRa”. The radio does not need to be in sight: it can stay in your backpack.

If there is a command post nearby

Join its Wi-Fi (whoever set it up has the name and password) and open Tesel as usual. At the top you will see “WiFi” and, if you tap it, “Connected to a command post”: you are in touch with the group. The next section explains it.

If you have neither

The downloaded map keeps working and you can write: messages go out by themselves when the connection returns or when you get near a command post. If someone in your group has a radio, stay close to them.

The command post

A command post is a computer that someone in the team brings to the area of operations. It does three things:

1. It creates its own Wi-Fi. It works without internet or phone masts, like a home Wi-Fi with no connection to the outside.
2. It is the team's server. Phones on its Wi-Fi pass messages through it, even without a radio. This is how people with only an iPhone, or no radio, stay included.
3. It is a bridge. With a radio connected at the post, what arrives by radio reaches the Wi-Fi and the other way round. And when the post gets internet back (by cable, satellite or a phone with data), it sends everything to the Tesel server and collects what the rest of the organisation wrote.

How to join a command post

• If you already have Tesel and are in the group: join the post's Wi-Fi and open the app. That is all. You will see “WiFi” at the top; tap it for “Connected to a command post”.
• If you do not have Tesel: join the post's Wi-Fi, open the address you are given in the browser (for example puesto.tesel.eu/app), choose your name and in “Groups” → “Join a group” tap “Scan QR code” to read the coordinator's invitation.
• If your phone says the Wi-Fi “has no internet”, that is expected: choose to stay connected. If you still have mobile data and the app does not reach the post, turn mobile data off while you are there.

Who sets up the post

Someone comfortable with computers prepares it in advance. Once prepared, in the area of operations it only needs switching on. It needs internet at least once every two months to renew its security certificate.

Radios

Tesel uses MeshCore radios: small devices that connect to your phone by Bluetooth and send messages to each other over LoRa, a radio signal that travels very far on very little power. In Europe they use the licence-free 868 MHz band.

• Which models: we are validating radios in the field and will publish recommended models here once testing is done.
• Setting it up: done once, from a computer with Chrome, with the official MeshCore web flasher and the “Companion Bluetooth” firmware.
• Range: from about a kilometre in a city to tens of kilometres between high places. Radios repeat each other's messages, so the more there are, the further messages travel. A radio on a high balcony or by a window helps the whole team.
• Why it is slower: the radio sends very little data, and the law limits how long it may transmit. Tesel puts urgent things first: SOS calls, then alerts, then messages and finally positions.
• MeshCore messages: if someone nearby uses the MeshCore app, their messages appear in the chat's “MeshCore” tab so they are not lost. To answer, use the MeshCore app.

If you have an iPhone

Over the internet Tesel works the same on iPhone. What Safari does not allow is connecting a radio by Bluetooth. Until the native app arrives, in an emergency you have two options:

• Join a command post.
• Try the Bluefy browser, which does allow Bluetooth. It is a stopgap we are still checking.

Privacy and security

• Everything in the group is encrypted with a key only its members have. Neither the server nor a command post can read the messages.
• The invitation is the key to the group. Whoever has it gets in. If it was shared with the wrong person, the coordinator can create a new group and invite everyone again.
• The group's keys are stored on your phone. Protect it with a screen lock. Leaving a group deletes it from the phone.
• Over radio the encryption is simpler: it keeps out casual listeners, not someone with means and determination. Do not send by radio what you would not say aloud in a public place.
• Your position is shared only when you choose.

If something does not work