APRS Connect

CW

CW needs APRS Connect Pro. It works in the Android app, in the iPhone app from version 1.14.2, and in the desktop app for Windows, Linux and Mac from version 1.14.1. On a computer says what is different there.

CW is Morse code: a tone keyed on and off in short and long marks. The CW screen, in the drawer, reads CW from the radio's sound as text and sends what you type as CW. Both happen on one page: listening at the top, the log of what was heard and sent in the middle, and sending at the bottom.

Listening

Press Listen. The line beside the button says what the app is doing: listening for CW, the pitch of the CW it hears, and then the speed it is reading as well. The light beside it comes on with each mark it hears, so you can see the Morse arriving before a letter of it has been read. The bar under it is the input level: it should move with the radio's sound. Under them, the dots and dashes themselves run along one line as they are heard, the newest at the right.

The button with dots and dashes beside the gear opens a Morse chart: every letter, figure, punctuation mark and prosign the app sends and reads.

The sound gets into the phone the same two ways as for SSTV: hold the phone near the radio's speaker, or use a cable. If an audio channel is running, CW listens through its input automatically. Otherwise, on Android, pick the input under Listen through in the settings behind the gear: Automatic, the phone's microphone, or a cable or USB sound card while one is plugged in. An iPhone listens on whatever is plugged in, or the microphone when nothing is. SSTV and CW can listen at the same time; they share one input.

The app finds the signal by itself: the tone being keyed, anywhere from 300 to 2,500 Hz, and the speed, from what it hears. A station that answers on another pitch or at another speed is read with its own. Each stretch of sending, with quiet either side, is one line in the log. The line under the button names the pitch being read. Press Read only pitch to stay on that station and leave the others out, and Read the whole band again to let it go. The same choice is in the settings as Read one pitch only, which reads within 100 Hz of the pitch you set.

The screen stays on while it listens, and listening carries on if you switch to another app. Android then shows a notification, APRS Connect is receiving CW, for as long as it listens. An iPhone shows its own microphone sign at the top of the screen instead. Listening stops when you press Stop or leave the CW screen.

Morse sent by hand varies, and noise and fading cost letters. A letter the app could not make sense of shows as *.

The log

What is heard and what you send go into the log, in the order they happened, each with the time, the speed and the tone. A line still being read shows a cursor at its end, and its last letters can still change as the app learns the sender's speed.

The log stays on this phone for 30 days, 500 lines at most. It is not in a backup and does not sync to your other devices. Share sends it as a text file, and Copy puts it on the clipboard. Clear removes it.

Sending

Type what to send in the box and press Send. While it goes out, the text already sent is shown in full and the rest is dimmed, and a line above the button shows the letter going out with its dots and dashes. Stop silences it at once.

  • If an audio channel is running, CW goes out through it, and its PTT (or the radio's VOX) keys the radio, as for a packet. An iPhone has no PTT line: the radio's VOX keys it.
  • Otherwise it plays through the phone's speaker: key your radio, or use its VOX.

The tone is sound, so into an FM radio it goes out as a keyed tone, and into an SSB radio's microphone it comes out as CW on the air, off your dial frequency by the tone's pitch.

Letters, figures and the usual punctuation are sent. A character Morse has no sign for is left out, and the screen says which before you send. The buttons under the box add a prosign, such as <AR> or <SK>: letters run together into one sign. You can type others the same way, in angle brackets.

Sending needs your callsign set in Settings, as any transmission from the app does.

Macros

The buttons above the box are macros. Pressing one puts its text in the box. Nothing is sent until you press Send. In a macro's text, {MYCALL} is your callsign and {CALL} is the callsign typed in Their call. The app starts with six: CQ, a reply, a signal report, 73, QRZ? and your callsign.

To change them, open the settings behind the gear. Tap a macro to edit its button and its text, move it up or down, or delete it. Add a macro makes a new one, up to 12. Restore defaults replaces yours with the six the app comes with.

Speed and tone

The settings behind the gear set how CW is sent:

  • Speed, from 5 to 60 words per minute.
  • Farnsworth spacing: letters sent at full speed with longer gaps between them, so the whole is slower. It is how many people learn: each letter keeps its rhythm, and you get time to think between them. Overall speed sets how slow the whole is.
  • Tone, from 400 to 1,200 Hz.
  • Keep VOX keyed: fills the gaps in the Morse with a quiet high tone, so a radio on VOX does not drop between letters. Leave it off when an audio channel keys the radio by PTT. Hold tone level sets how far below the Morse that tone sits, 20 dB by default: raise it only if your radio's VOX still drops. A longer VOX delay on the radio, where it has one, does the same job with no tone at all. The same level is used for the CW ID after an SSTV picture.

The app reads any speed it hears, whatever these say.

On a computer

The desktop app has CW from version 1.14.1, on Windows, Linux and Mac, with the same screen. What is different:

  • What it listens to and sends through. With an audio channel running, CW listens on the channel's sound input and sends through its output, keyed by its PTT line or the radio's VOX. Without one, it uses the sound devices chosen in the settings behind the gear: Listen through for the input, and Transmit through, under Sending, for the output. Each is System default at first, or a device by its name, such as a cable or USB sound card to the radio. A chosen device that is unplugged is shown as not connected, and CW does not move to another one. A new choice of input is used from the next Listen.
  • SSTV and CW listening on the same device share it, as on a phone. On different devices, each listens on its own.
  • The log stays on the computer, for the same 30 days and 500 lines.
  • Listening carries on while the app is closed to the tray, and stops when you leave the CW screen.

Last updated 20 October 2026

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