Background

Add classic Apollo-era "Quindar" tones (2525 Hz intro, 2475 Hz outro, ~250 ms each) to MOX/PTT engagement on phone modes — fun cosmetic feature for SSB ops who want NASA mission-control aesthetic.

Two flavors selectable per-user:

Morse style uses the active CW pitch (or a configurable Quindar pitch — TBD) as the carrier, generated with the same envelope as the sine version. Outro BK is intentionally longer than the 250 ms intro K because the signoff convention warrants the extra emphasis.

Ships disabled by default; opt-in per-user.

Trigger surface — single coordinator

Add TransmitModel::requestPttOn(source) / requestPttOff(source) as the entry point for all "user wants to key/unkey" intents (where source ∈ {Mox, TciHardware, TciDax, …}). Existing setMox() / setTransmit() stay as low-level emitters; the coordinator runs the tone state machine before/after them.

State machine

Idle ──pttOn──▶ Engaging  (intro tone, 250 ms)
                   │
                   ▼ tone done
                Live  (mic audio)
                   │
              pttOff request
                   ▼
              Disengaging  (outro tone, 250 ms; xmit 1 still set)
                   │
                   ▼ tone done → emit xmit 0
                Idle

Engaging/Disengaging drive an atomic QuindarPhase read by AudioEngine on the audio thread.

DSP — ClientQuindarTone

New stage in src/core/ClientQuindarTone.{h,cpp}, lock-free atomic-driven (mirrors ClientGate / ClientTube shape):

• Tone style: 2525 Hz (intro) / 2475 Hz (outro) sine, 5 ms cos² ramp envelope to avoid clicks.
• Morse style: pre-rendered K (intro) / BK (outro) at 45 WPM, single carrier frequency (default 750 Hz, configurable). Element timing: dot = 1200/45 ≈ 26.67 ms, dash = 80 ms, intra-char gap = 26.67 ms, inter-letter gap = 80 ms. Each element shaped with the same 5 ms cos² envelope.
  • K = dah-dit-dah → 9 units → ~240 ms total
  • BK = dah-dit-dit-dit + inter-letter + dah-dit-dah → 21 units → ~560 ms total
• Replaces mic samples wholesale during Engaging/Disengaging (simpler than ducking).
• Inserted after PooDoo chain in the TX path so the tone/morse is pure (no comp/EQ coloration).
• Injects directly into the DAX TX byte stream AudioEngine already emits.

MOX-off defer

requestPttOff(source):

1. If Quindar enabled + phone mode + currently Live → audio->startQuindarOutro() + QTimer::singleShot(outroDurationMs, …, sendPttOff).
2. Else → sendPttOff() immediately (current behavior).

outroDurationMs is style-dependent: 250 ms for Tone, ~560 ms for Morse BK. Asymmetric outro durations are fine — the timer length is computed at request time from the active style.

The MOX button visibly stays lit during the outro because m_mox doesn't flip until the timer fires — the "stickiness" is the outro tone duration, which is the correct UX (user sees what's happening).

Phone-mode gate

isPhoneMode() = mode ∈ {USB, LSB, AM, FM, NFM, DIGU, DIGL} checked at request time on the active slice. CW / FT8 / DIGITAL → bypass Quindar entirely.

Settings (AppSettings keys)

• QuindarEnabled (default False)
• QuindarStyle (default Tone; values Tone | Morse)
• QuindarLevelDb (default -6)
• Tone style:
  • QuindarIntroFreqHz (default 2525)
  • QuindarOutroFreqHz (default 2475)
  • QuindarDurationMs (default 250, range 100–500)
• Morse style:
  • QuindarMorseWpm (default 45, range 20–60)
  • QuindarMorsePitchHz (default 750, range 400–1200)

UI

Right-click MOX → "Quindar..." popover with:

• Enable toggle
• Style segmented control: [ Tone ] [ Morse ]
• Level slider (-20 … 0 dB)
• Style-conditional fields:
  • Tone: intro freq, outro freq, duration spinner
  • Morse: WPM spinner (20–60), pitch slider (400–1200 Hz)

No menu-bar entry — keep it tucked under the right-click.

Files touched

Edge cases

• Rapid MOX toggle within outro window — coalesce: re-engaging during outro skips intro and resumes Live (otherwise the user feels a dead zone equal to outro + intro = up to ~800 ms in Morse style).
• Mode change mid-transmission — keep current phase (don't truncate or restart).
• Other client keys our radio (multi-Flex) — observed-only; doesn't trigger our tone (m_transmitting rising via radio-side status ≠ our PTT request).
• Hardware PTT via radio-side serial PTT — out of scope. Document as MOX-only.
• Disconnect mid-outro — drop pending xmit-0 timer; radio handles unkey via session teardown.

Open UX question

The "MOX button stays lit ~250 ms after release" feels correct, but worth validating on actual footswitch hardware — the streamcontroller plugin reflects MOX state back to the Stream Deck button, so there's a visible delay on the physical button too. If that delay feels off, alternative is to flip MOX visually immediately and only defer the actual xmit 0 (slight UI dishonesty but maybe worth it).

Risks

• Niche feature — many ham contest ops will find Quindar annoying or unprofessional. Ships disabled by default.
• Doesn't compose with hardware serial PTT (radio-side keying happens before AetherSDR sees it). Footswitch via TCI is fine; serial PTT footswitch is not. Document explicitly.

73, Jeremy KK7GWY & Claude (AI dev partner)