MPL Configuration
See the full list of MPL aliases and PL frequencies from your loaded configuration.
MPL is the part of a codeplug where the tone is left to the operator. Most channels are programmed with a fixed squelch tone; a channel set up for MPL instead offers the tone positions in the codeplug's MPL list and waits for the operator to pick one. This page explains how the two sides fit together — which channels are gated this way, what the radio decides, and what to check before you transmit.
Overview
| Piece | Where you read it | What it gives you |
|---|---|---|
| The tone positions | MPL Config on the Communications hub | Every position with its alias and its receive, transmit, and direct settings |
| One position, closely | The same list, read line by line | The squelch types and tone frequencies behind an alias |
| Which channels are gated | A channel's Squelch block | Whether the channel is user-selectable, and on which direction |
| Term | Plain meaning |
|---|---|
| MPL | The set of selectable squelch tone positions in the codeplug |
| PL | A tone squelch — the radio only opens when it hears the programmed tone |
| DPL | A digital version of the same idea, using a code instead of a tone |
| Carrier squelch | No tone at all — the radio opens on any signal |
| User-selectable PL | The channel does not fix a tone; the operator picks a position |
info
Nothing in the app changes a radio. These screens are a reference so you can see what a radio will do before you touch it.
Getting Here
- From the Home screen, open References.
- Select Communications.
- Choose a codeplug on the Radio Info screen.
- Tap MPL Config to read the position list, or open a channel and read its Squelch block to see whether that channel is gated.
How the Gating Works
A channel only offers the MPL positions when it is programmed to. The channel's own squelch type is what decides it.
| The channel's squelch type | What the channel details show | What the radio does |
|---|---|---|
| Carrier squelch | Just the type | Opens on any signal; no tone involved |
| Tone squelch with a frequency | The type and the tone frequency | Uses that fixed tone; the MPL list is ignored |
| Digital squelch with a code | The type and the digital code | Uses that fixed code |
| Network access code | The type and the code | Uses that fixed code |
| User-selectable (MPL) | A note reading User-selectable (MPL) | Uses whichever MPL position the operator selects |
And because receive and transmit are programmed separately, a channel can be selectable on one direction only:
| Note on the channel | What it means |
|---|---|
| User-selectable (MPL) | Both receive and transmit are selectable |
| RX: User-selectable (MPL) | Receive is selectable; transmit uses the channel's own fixed setting |
| TX: User-selectable (MPL) | Transmit is selectable; receive uses the channel's own fixed setting |
caution
An MPL note means the tone is not decided by the codeplug. Two radios on the same channel with different positions selected may not hear each other at all, even though both are on the correct frequency.
Checking a Channel Before You Transmit
- Open the channel from Zones or Channels.
- Read the Frequencies block. Confirm the receive and transmit frequencies are the ones you were given.
- Read the Squelch block, which shows receive on the left and transmit on the right.
- Decide from what it shows:
| What you see | What to do |
|---|---|
| A fixed tone on both sides | Nothing more to do — the tone is set in the codeplug |
| An MPL note | Note the position you have been told to use, then confirm it exists in the MPL list |
| Carrier squelch | Expect to hear all traffic on the frequency, including other agencies |
| Nothing but a type | That type needs no tone or code |
- If there is an MPL note, open MPL Config and find the position by number or alias.
- Confirm its RX Type, TX Type, and tone frequencies are what the comms plan expects.
tip
Read the position's transmit line as carefully as its receive line. A position can be set to receive on carrier squelch and transmit a tone, which means you hear everything but only tone-equipped radios hear you.
Reading the Position List
| Line on a position | What it means |
|---|---|
| n. Alias | The position number, then the alias the radio displays |
| RX Type | Receive squelch type |
| TX Type | Transmit squelch type |
| RX FREQ | Receive tone frequency |
| Direct FREQ | Tone frequency used in direct/talkaround |
- Open MPL Config from the hub. The header reads MPL.
- Scroll the list, or use the Search option in the menu to filter by alias.
- Positions are listed in the order the radio offers them, so the number in front of the alias is the count you step through on the radio.
Full line-by-line guidance is in MPL Radio Detail, and the list screen itself is described in MPL Radio List.
Loading, Empty, and Error States
| State | What you see |
|---|---|
| Loading | A loading indicator while the positions are fetched or read |
| No positions | An empty list — no channel in this codeplug uses selectable tones |
| Search with no matches | An empty list until you clear the search |
| Request failed | An alert with the message returned by the server |
| Codeplug not downloaded, no connection | "This codeplug isn't available offline." |
How This Connects
- Where both halves come from. The positions and the channels both belong to the codeplug you opened on Radio Info. They are fetched separately as you open each screen, and read from the downloaded copy on the device when you have no connection — which is why the MPL list can be empty while channels still load, on a partial import.
- How a channel points here. The Squelch block in Zone & Channel Details is filtered to the channel's active squelch type, so it either shows a real tone or the MPL note. It never shows both.
- Where the positions live. The list itself is MPL Radio List, and one position's fields are covered in MPL Radio Detail.
- Radio controls may change the tone too. A button or switch can be assigned to tone functions on some radios, so read Buttons & Switches for the radio you are carrying, and Menu Items for what the MPL code on the radio display means.
- Used with incidents. A comms plan that names a tone is checked against these screens before you key up — see Incident Comms Tab. Talking through the app instead of the radio is a separate path, see Audio Channels.
- Offline and reconnect. Everything described here reads offline for a downloaded codeplug. When the connection returns, reopen the section so it fetches the current version — a re-imported codeplug can change both the channel's squelch type and the position list.
Troubleshooting
| If this happens | What to do |
|---|---|
| A channel says MPL but the list is empty | The codeplug is inconsistent or partially imported. Confirm the tone with whoever programs the radios. |
| You cannot find a tone frequency for a channel | The channel is user-selectable, so no tone is fixed. Read the MPL positions instead. |
| Only one direction says MPL | That is deliberate. The other direction uses the channel's own fixed setting. |
| You can hear others but they cannot hear you | Check the transmit side of both the channel and the selected MPL position — the transmit tone may not match theirs. |
| You hear traffic from another agency | The receive side is likely carrier squelch, which opens on any signal on that frequency. |
| Searching a tone frequency finds nothing | Search matches the alias. Scroll and read the frequency lines. |
| Positions do not match the radio | You may be reading a different codeplug. Check the name in the hub header. |
| "This codeplug isn't available offline." | Open this codeplug once while connected so it downloads, then it reads offline. |
Related Pages
⬅️ Previous: MPL Radio Detail | Next: Buttons & Switches ➡️