MOP

1Welcome

MOP is a complete digital messaging network for FM: its own high-speed modem, a mesh that builds itself, and delivery you can trust, on the radio you already own. No internet, no repeater, and no central station needed.

Short bursts, not phone calls

Most digital modes on FM work like a telephone call: connect, shake hands, send, wait, disconnect. That's fine for one long email to one gateway. For a short message it means seconds of setup before the first word goes out, and while that call is running, everyone else on the frequency waits. MOP works the way radio is at its best: like a broadcast.

Think of text messaging on a phone, except the cell towers are the MOP stations themselves. You pick a callsign, type, and press Enter. MOP finds the way: straight to the other station if it can hear you, or hopping through other MOP stations if it can't. When the message arrives, the other station confirms it and you see ✓ delivered, even when it took three hops to get there. If the other station is switched off, your message waits and goes out by itself the moment they're back on the air.

Every MOP station sends a short beacon now and then: "I'm here, this is where I am, and these are the stations I can hear." From those beacons, and from everything else it hears, every MOP station learns the map of who can reach whom. That map is the mesh, and it repairs itself when stations come and go.

What's inside

How MOP compares

You probably know one or more of these. Each is good at its own job; here's where MOP fits.

MOP doesn't replace your other modes: you can keep packet and VARA FM set up next to it. Only one program can use the sound card at a time, so close the others while MOP is connected.

What you need

• A computer with Windows 10 or 11.
• Your FM radio (2 m, 70 cm, or any FM channel you're licensed for).
• A connection between radio and computer. That's either an interface (a Digirig, a SignaLink, an AIOC cable…) or simply the radio's own USB cable (FT-991A, IC-7300, IC-705 and similar have a sound card built in).
• Your amateur radio license and callsign.
• Someone to talk to: a friend with MOP, or a second radio of your own.

You do not need any other software. MOP brings its own modem.

How to read this manual

Words in a grey box, like ▶ Connect, are exactly what you'll see on the screen: a button, a tab, or a choice in a list. Keys on your keyboard look like Enter. Steps are numbered; do them in order.

2Install MOP

About five minutes. MOP comes as one zip file; there's no installer to click through.

Download

1. Open your web browser and go to mopx.duckdns.org/download.
2. Click the big orange ⬇ Download MOP button. Your browser saves a file called something like MOP-0.19.2-windows.zip in your Downloads folder. It's large (a few hundred MB), so give it a minute or two.

Unpack

3. Open File Explorer: the yellow folder on the taskbar at the bottom of the screen. Click Downloads on the left.
4. Right-click the MOP zip file and choose Extract All….
5. A box opens showing where the files will go. The Desktop is a good place: click Browse…, pick Desktop, then click Extract.
6. A new folder opens, called MOP-0.19.2. It holds many files. The one that matters is MOP.exe, with the MOP icon (coloured bars with dots on top).

Make a Desktop shortcut

7. Right-click MOP.exe. On Windows 11, click Show more options first.
8. Choose Send to → Desktop (create shortcut).

From now on you start MOP by double-clicking MOP on your Desktop.

The first start

Double-click MOP. The first time, Windows may show a blue box:

After a few seconds the MOP window opens. On to the tour.

3The MOP window

One bar along the top, five tabs below it.

The five tabs

Settings at a glance

Click ⚙️ Settings. On the left is a list of five sections. Each has a coloured dot:

Click a section to see it. At the bottom right is one button, 💾 Save and apply, which saves all sections at once. Nothing you change counts until you press it.

4Your station

Who you are on the mesh, what equipment you use, and where you are.

Where: ⚙️ Settings → Station

🪪 Identity

1. Station ID: type your callsign in the first box, for example KO6IKR.
2. In the box next to it, pick an SSID only if you run more than one MOP station (for example 1 for your second station). One station? Leave it at (none).
3. Role: leave it on station.
   relay means "I'm on a good hill, pass messages along for others". gateway means "this station also shares what it hears on the internet map".
4. Key Status: click Generate, then Yes. MOP makes your personal signing key. You only do this once.

📻 Equipment

5. Radio: open the list and pick your radio, for example Yaesu FT-991A. Not in the list? Just type its name.
6. Interface: pick what connects radio and computer, for example Digirig Mobile, or Radio's built-in USB audio if you only use the radio's USB cable.

These two go into your beacon, so other operators see what you're running, on their map and in their Stations list. They don't change how MOP works.

📍 Position

Where your station is, so it shows on the map.

7. Source: choose Manual only, unless a GPS receiver is plugged in (see below).
8. Latitude and Longitude: type your position in degrees, for example 34.10413 and -118.20832. West and south are negative.
9. Beacon: how precisely your position goes out on the air. Everyone can read it.

   Exact position (~1 m)	Your exact spot
   Rounded ~100 m	Your street, not your house. A good choice at home
   Rounded ~1 km	Your neighbourhood
   Grid square only	Only your Maidenhead grid square

10. Leave Set Grid from position ticked: MOP works out your grid square for you.

Below the position, MOP shows the Ground elevation here, in metres and feet. It looks this up on the internet from NASA and USGS elevation maps. No internet? It says so, and fills it in later.

With a GPS receiver

Set Source to GPS (manual if no fix). Pick the GPS's GPS port (press 🔄 to look again for newly plugged-in devices) and its Baud (usually 4800 or 9600), then click ▶ Connect GPS. Once it has a fix, MOP uses it; ⬇ Use GPS fix copies that position into the Latitude and Longitude boxes, so it stays even when the GPS is unplugged.

Press 💾 Save and apply before you move on.

5Connect your radio

The most important chapter. MOP needs two things: sound in and out, and a way to key the transmitter (push-to-talk, or PTT).

Where: ⚙️ Settings → Radio

Before you start: plug the interface (or the radio's USB cable) into the computer and switch the radio on. Windows only shows devices that are plugged in.

🔊 Sound

1. Input (RX): open the list and pick your interface's microphone. It's usually called USB Audio Device, USB Audio CODEC or USB PnP Sound Device. Do not pick your computer's own microphone.
2. Output (TX): pick the same interface's speakers (same kind of name).
3. Look for a ✓ next to each one. A ✗ means Windows has that device at the wrong setting. Appendix B fixes it in two minutes.

🎙️ Push-to-talk

4. Method: pick how MOP keys your radio. Find your setup in the table below.
5. Fill in the boxes that appear under it. Most methods only ask for a Port (like COM5; Appendix A shows how to find yours) and sometimes a Speed.
6. Tune the radio to a clear frequency, or connect a dummy load, and press 🔴 Test PTT (1 s). Your radio should transmit for one second.

Recipes

Find your setup and do just that one. Each recipe ends with 💾 Save and apply.

🚫 Keep the sound clean: no processing

On the radio: switch these OFF (for transmit)

On the radio: switch these OFF (for receive)

Radios differ: look in your radio's manual for the menu names. If you can, use a DATA mode and the data port (6-pin mini-DIN) or the radio's USB audio: those paths skip most voice processing. In the microphone jack, also keep MIC GAIN moderate: too high squashes the tones just like a compressor.

On the computer: switch off Windows sound effects

Windows can "improve" the interface's sound as well. Turn that off, once, for both directions. Appendix B shows where: in the same Properties windows where you set 48 kHz.

• Enhancements tab (or Audio enhancements in Windows 11): Off / tick Disable all enhancements. That includes noise suppression, echo cancellation, and loudness equalization.
• Any "sound booster", headset or gaming audio program (Realtek Audio Console, Nahimic, Dolby, Sonic Studio…): off for the interface.

📊 Levels

Leave TX drive at 70 % and RX gain at 100 % to start with.

📶 Modem

Click Modem in the list on the left. It should say Backend: ofdm and Level: Auto. Leave it like that: MOP picks the fastest speed the path allows by itself.

Now press 💾 Save and apply. A box says Settings saved; click OK.

6On the air

Connect, send a beacon, and see the other station appear.

1. Tune both radios to the same simplex frequency your group uses for MOP, in FM wide (not narrow; see chapter 5).
2. Click ▶ Connect at the top right. The status turns green: ● Connected.
3. Go to ⚙️ Settings → Beacons & Internet and click 📡 Beacon Now. Your radio transmits a short burst, about a second. That's your station announcing itself.
4. Ask the other station to do the same. When their beacon arrives, they appear in the 👥 Stations tab and on the 🗺 Map.

Automatic beacons

In ⚙️ Settings → Beacons & Internet, Enable beacons sends a beacon by itself every Interval (2 hours unless you change it). MOP also learns about stations from everything it hears, so after a while stations appear without anyone pressing anything.

7Messages

Like texting on a phone: one conversation per station, with ticks that tell you when it arrived.

Where: 💬 Messages

The list on the left has three parts:

Send your first message

1. Under STATIONS, click the other station's callsign. Not there yet? Click + at the top of the list and type their callsign, for example KO6IKS-2.
2. Type your message in the box at the bottom, for example Hello from MOP! 73.
3. Press Enter, or click Send. For a new line without sending, press Shift + Enter.
4. Your radio transmits. Watch the mark next to your message.

What the marks mean

📣 CQ / Bulletins

Click 📣 CQ / Bulletins and type: your message goes to every station in range, and relays repeat it a few hops further. Nobody confirms a bulletin, so there's no ✓.

🚨 Emergency

Only for real emergencies. A message here travels through the whole mesh: every station passes it on, and every MOP alerts its operator. MOP asks you to confirm before it sends.

📎 Files, pictures and your position

• 📎 next to the message box attaches a file or picture. Pictures are made smaller automatically. Keep files small: radio is slow compared to the internet.
• 📍 attaches your position, which the other station can open on their map.
• Files you receive are kept in Documents\MOP\attachments.

More

• The bar above each conversation shows how well you hear each other, the speed level, and buttons for the Map and a Level test.
• Right-click a conversation to delete it.
• Prefer the classic mailbox view (Inbox, Outbox, Sent, Trash)? Click Folders at the top of the list; Conversations brings you back.

8Groups

One message to several stations, for a net, a club, or an ARES team.

A group message goes out once; every member in range receives it and confirms it, one after the other. Members who are out of range get their own copy, through relays or later.

Make a group from the Stations list (easiest)

1. Click the 👥 Stations tab.
2. Click the first station you want in the group.
3. Hold Ctrl and click each of the others. (Or hold Shift and click to pick everything between two stations.) The panel on the right lists who you picked.
4. Click 👥 Create group at the top right.
5. Type a name, for example ARES LAX-NE, check the ticked members, and click OK.
6. MOP jumps to 💬 Messages. Your group is under GROUPS, ready for its first message.

Or from Messages

Under GROUPS, click ＋ New group…, type a name, tick the members, and click OK. A member who's never been heard? Type their callsign in the box at the bottom and click Add.

Change a group

• Add stations: in 👥 Stations, pick them, right-click, and choose Add to group → the group.
• Rename, add or remove members: open the group in Messages and click Members.
• Delete: right-click the group in Messages → Delete group…. Its messages stay.

Members learn about the group with your first message to it. From then on, anyone in the group can write to all members.

9Stations

Every station MOP knows: heard on the air, passed along by relays, or saved as a contact.

Where: 👥 Stations

Click a station and the panel on the right shows everything about it: route, signal both ways, position, ground elevation, the radio and interface they use, who they hear, and which of your groups they're in.

• Message opens your conversation with them (double-clicking the row does the same).
• Map shows them on the map.
• Name and Notes, then Save contact, keep them in your contacts.
• Add contact (top right) adds a station you haven't heard yet.
• The search box finds a callsign, name or grid.

10The map

Where everybody is, and who can hear whom.

Where: 🗺 Map

• Every station heard is a dot. Lines between stations are links, coloured by signal quality.
• Click a station for its details. The box stays open until you click again.
• 📍 Me brings you back to your own position.
• Dark and Map switch between a dark background and a normal street map.
• As you zoom in, the Maidenhead grid appears, down to 8 characters.
• Map pictures you've looked at are kept on your computer, so those areas still show without internet.

Map data © OpenStreetMap contributors.

11The public map & updates

Optional: share what your station hears on the MOP-IS map, which anyone can watch in a browser.

Share what you hear

Where: ⚙️ Settings → Beacons & Internet, the 🌐 Internet box

1. Tick Share what this station hears on the public MOP-IS map.
2. Leave Server empty (MOP uses https://mopx.duckdns.org) and Every as it is.
3. Press 💾 Save and apply, and make sure MOP is ● Connected.
4. The status line shows ✓ uploaded after the first upload, or press ⬆ Upload now. 🌍 Open map opens the map in your browser.

Updates

With Check for MOP updates ticked (it is, unless you untick it), MOP asks the server once a day whether there's a newer version. If there is, an orange ⬆ MOP … available button appears at the top.

1. Click it. Your browser opens the download page.
2. Download and Extract All… the new zip, exactly as in chapter 2.
3. Start MOP.exe from the new folder, and make a new Desktop shortcut (delete the old one).
4. Happy with the new version? Delete the old MOP-… folder.

Your callsign, settings, messages and key carry over by themselves (chapter 12 explains why).

12Your files & backups

MOP keeps the program and your things in two separate places.

Inside Documents\MOP

Back up your key

1. Open File Explorer, click Documents on the left, and double-click MOP.
2. Find the file named after your callsign, ending in .key.
3. Copy it to a USB stick (right-click → Copy, then on the stick right-click → Paste).

13When something's wrong

Find what you see in the left column.

🚦 MOP won't start

🎙️ Radio

💬 Messages

🌍 The public map

🆘 Still stuck? Send the log

1. Click the 📡 Radio tab. The Activity Log on the right lists everything MOP did.
2. Click inside the log, press Ctrl + A (select all), then Ctrl + C (copy).
3. Paste it (Ctrl + V) into an email to whoever gave you MOP, and say what you expected to happen.

14Where MOP is going

MOP is young and growing fast. Here's what it can do today, where you are on the road, and what's coming. Plans can change; your feedback helps decide what comes first.

1. Done

   A modem of its own

   32 tones in one FM voice channel, from a tough 1,050 bit/s up to 9,450 bit/s on a clean path. MOP picks the speed for each station by itself.

2. Done

   A mesh that finds its own way

   • Beacons, routes, and relays that pass messages along, with the ✓ coming back the same way.
   • Messages wait for stations that are off the air (store-and-forward).
   • Conversations, groups, CQ bulletins, and the emergency channel; files, pictures, positions.
   • Every message signed; compressed when that makes it shorter.
3. Done

   Ready for your shack

   • Push-to-talk for practically every radio and interface.
   • The public MOP-IS map, the download page, and automatic update notices.
   • Radio, interface and ground elevation for every station; this manual.
4. You are here MOP 0.19

   The first testers on the air

   That's you. Every beacon, delivered message, and problem you report shows what works on real radios, real antennas and real hills. When something goes wrong, send the Activity Log (chapter 13).

5. Next

   The EmComm tab

   A sixth tab for emergency and public-service work, built on the forms and net tools served agencies already know. See the sketch below.

6. Next

   Mesh islands, linked: coast to coast

   Gateways pass messages between separate MOP meshes over the internet, directly from gateway to gateway, with no central server. A message from Los Angeles reaches a mesh in New York, and the ✓ still comes back. See the story below.

7. Later

   Faster and further

   • Big files in fewer transmissions.
   • Shorter messages through smarter compression, tuned to ham traffic.
   • Signed beacons, and the published on-air specification.
8. Goal

   MOP 1.0

   A dependable mesh that any served agency, club, or ARES group can put on the air and count on when the phones and the internet are down.

A first look at the EmComm tab

A design sketch, not the finished screen. It brings back and improves the EmComm tools from an earlier MOP, on top of today's mesh:

The bigger picture

Coming next: a message from Los Angeles to New York

How a message will cross the country once gateways are linked. Callsigns are made up.

1. W6QQQ in Los Angeles writes to K1ZZZ in New York. Her MOP doesn't know K1ZZZ, but from the beacons it hears it knows a gateway nearby, KO6IKR-GW, that has internet.
2. MOP sends the message as one short burst, about a second on the air. No connecting, no handshake.
3. A relay on a hill hears it and passes it on toward the gateway.
4. The LA gateway doesn't have K1ZZZ nearby, but it has heard from the New York gateway, W1ABC-GW, that K1ZZZ is one of its stations.
5. The LA gateway sends the message straight to the New York gateway over the internet. Gateway to gateway, no central server. The signature travels with it, so New York can check it really came from W6QQQ.
6. K1ZZZ's radio is off. The New York gateway holds the message and waits.
7. K1ZZZ switches on. As soon as his station is heard, the gateway sends him the message.
8. K1ZZZ's MOP confirms, and the confirmation travels all the way back. In Los Angeles, W6QQQ's message turns to ✓ delivered.

Everything up to step 3, and steps 6 to 8 inside one mesh, works today. Steps 4 and 5, the gateways talking to each other, are what's being built next.

AFinding your COM port

When an interface or radio connects over USB, Windows gives it a number like COM5. MOP needs that number to key your radio.

1. Plug in the interface or radio, and switch the radio on.
2. Press the Windows key (bottom-left of the keyboard, with the Windows logo), type device manager, and click Device Manager.
3. Find Ports (COM & LPT) and click the little arrow › in front of it.
4. Look for a line like these, and write down the number in brackets:

BSetting your sound card to 48 kHz

MOP's modem needs the interface's sound card set to 48 kHz, both directions. Two minutes.

Speaker side (MOP → radio)

1. Right-click the speaker icon 🔊 at the bottom-right of the screen, next to the clock.
2. Click Sound settings.
3. Scroll down and click More sound settings (Windows 11) or Sound Control Panel (Windows 10). A small window with tabs opens.
4. On the Playback tab, click your interface once (USB Audio Device, USB Audio CODEC or USB PnP Sound Device).
5. Click Properties, then the Advanced tab.
6. Under Default Format, choose 2 channel, 16 bit, 48000 Hz (DVD Quality), or 1 channel if that's all it offers. Click OK.

Microphone side (radio → MOP)

7. In the same small window, click the Recording tab.
8. Click your interface's microphone once, then Properties → Advanced.
9. Choose … 48000 Hz again, and click OK, then OK to close.

Give your interface its own name

With more than one USB sound card plugged in (a Digirig for each radio, a USB headset, a webcam), they often all have the same name. Windows lets you rename them, and MOP then shows your name.

10. In the same small sound window, on the Playback tab, right-click the interface and choose Properties.
11. On the General tab, the name at the top is a box you can type in. Replace it with a short name of your own, for example Digirig 991. Keep it under about 25 letters. Click OK.
    Not sure which one it is? Unplug the interface: the one that disappears is it.
12. Do the same on the Recording tab for its microphone side, for example Digirig 991 RX.
13. In MOP: ⚙️ Settings → Radio, press 🔄 Refresh, pick your newly named devices, and press 💾 Save and apply.

Switch off sound enhancements (both sides)

14. Still in the Properties window of the interface (Playback side, then Recording side), look for an Enhancements tab. Tick Disable all enhancements (or untick every effect).
    Windows 11 may show this as Audio enhancements: Off in the device's page in Sound settings instead.
15. If you see an Advanced tab option Enable audio enhancements, untick it too. Click OK.
16. On the Communications tab of the small sound window, choose Do nothing, so Windows never turns the interface down when it thinks you're on a call.

Back in MOP, ⚙️ Settings → Radio now shows a ✓ next to both.

CWords you'll meet

MOP is free for licensed amateur radio operators. It includes third-party components under their own licenses (Qt and PySide6 under the LGPL v3); see LICENSE and THIRD_PARTY_NOTICES.md in the MOP folder. Elevation data: Terrain Tiles (SRTM/NASA, USGS 3DEP). Map data © OpenStreetMap contributors. 73 de KO6IKR.