SimpleFT8

SimpleFT8 needs the audio output of your radio (or SDR) reaching the app. Three common paths:

USB audio interface

A SignaLink, Digirig, RIM-Lite, or built-in USB audio on the radio. The cleanest option. Pick the device in Settings → Audio (macOS).

Headphone-to-mic cable (with attenuation)

Old-school but works. Pad down the level so you don't blow the mic input.

Acoustic coupling

Hold the radio speaker near the iPhone mic. Surprisingly good when the signal is strong.

macOS only — System Audio capture

In Settings → Audio set "Input source" to "System Audio". The app captures whatever your Mac is playing via ScreenCaptureKit — perfect for SDR software (SDR++, CubicSDR) or WebSDR pages in a browser. No virtual audio cable required.

1. Set your operator callsign and Maidenhead grid in Settings.
2. Set your dial frequency (default 14.074 MHz on 20m, the global FT8 calling channel).
3. Tap Call CQ. The app queues a "CQ <your call> <grid>" for the next slot of your TX parity and transmits.
4. If someone replies, tap their decode row to accept — the QSO state machine handles the rest.
5. After "73", tap Log QSO to save the contact.

1. Watch the RX list. Any decode that starts with "CQ" is someone calling.
2. Tap the row. The app flips slot parity, queues "<them> <you> <your grid>", and enables TX.
3. The state machine sends each subsequent step (R-XX, RR73, 73) automatically when their reply lands.

Both opt-in toggles in Settings → Operating:

Both default OFF — the app stays in full operator-driven mode until you opt in.

FT8 stations alternate slots: one transmits on :00 and :30, the other on :15 and :45. SimpleFT8 auto-flips parity when you accept or reply to a call so you naturally land on the opposite parity.

If you're CQing alone for > 3–6 minutes and Randomly flip slot parity is on, the app will randomly flip parity to break a potential cold-start deadlock with another solo CQer on the wrong side.

The waterfall above the decode list shows audio activity in real time. Tap any point on the waterfall to set your TX audio frequency — 1500 Hz (the WSJT-X default) sits in the middle of the SSB passband; other frequencies dodge co-channel QRM.

Every completed QSO lands in the Log tab. The export button up top writes the entire log as an ADIF file — drop it into LoTW, QRZ Logbook, or any logger that speaks ADIF (everything does).

Decodes upload via our backend at simpleft8.strangeloop.nl, which rate-limits and forwards as IPFIX UDP to PSK Reporter on your behalf. This stops a misconfigured client from accidentally hammering the upstream service.

Off by default. Requires you set a contact email (PSK Reporter wants one for misbehaving-client outreach).

Off by default. Separate from PSK Reporter — you can enable either, both, or neither.

Maidenhead pins for every layer you've enabled:

amber — stations you decoded

green — stations who heard you (PSK Reporter, opt-in)

cyan — SimpleFT8 ops online right now (opt-in)

Below the map: stats (best SNR, furthest, unique grids) and a text list per layer.

Do I need a ham license?

To transmit, yes. Receiving is unrestricted in most places. Check your local rules.

Will it interop with WSJT-X / JTDX?

Yes — bit-exact encode + WAV regression decode tests pass. Same FT8 messages, same audio frequencies.

I see −20 dB reports — is that bad?

No, that's normal. FT8 decodes down to roughly −24 dB.

My TX clock seems off.

SimpleFT8 syncs to NTP every 30 minutes. The Station card on the RX tab shows your offset.

Why is iOS audio so limited?

iOS doesn't expose ScreenCaptureKit, so live decode on iOS is mic-only. Use the macOS app if you want SDR-software capture.

How does the app handle my decoded callsign data?

All decode metadata stays on your device unless you opt into PSK Reporter or the presence map. Even then, only your call, your grid, and a per-install device identifier leave the device.

No analytics, no ads, no third-party SDKs. The app is fully self-contained by default; every external feature is opt-in.

Full Privacy Policy →

github.com/jarombouts/SimpleFT8 →

Email: jeroen@strangeloop.nl