# SatMaster — F4BPO Satellite Tracker

Amateur satellite tracking application with Doppler correction for FlexRadio 8600 and rotor control via PstRotator.

**Stack:** Go + Wails v2 + Svelte  
**Platform:** Windows (primary), Linux/macOS (compilable)

---

## Features

- 🗺️ **World map** — real-time satellite positions on Leaflet dark map, footprint overlay
- 📡 **Polar plot** — az/el pass track with AOS/LOS markers, current position animation
- 🕐 **Pass prediction** — 24h upcoming passes, Max El, duration, quality rating
- 📻 **Doppler correction** — automatic TX/RX frequency correction via FlexRadio 8600 TCP API
- 🔄 **Rotor control** — Az/El commands to PstRotator via UDP XML protocol
- 🛰️ **TLE management** — auto-fetch from tle.oscarwatch.org with local cache fallback

---

## Architecture

```
SatMaster/
├── main.go                    # Wails entry point
├── app.go                     # App struct, Wails bindings, position loop
├── wails.json                 # Wails project config
│
├── backend/
│   ├── tle/
│   │   └── manager.go         # TLE fetch (oscarwatch.org), cache, parse, lookup
│   │
│   ├── propagator/
│   │   └── engine.go          # SGP4 propagation, az/el, pass prediction
│   │
│   ├── doppler/
│   │   └── calculator.go      # Doppler shift computation (range rate → Hz correction)
│   │
│   ├── flexradio/
│   │   └── client.go          # FlexRadio SmartSDR TCP API (port 4992)
│   │
│   └── rotor/
│       └── pstrotator.go      # PstRotator UDP XML protocol (port 12000)
│
└── frontend/src/
    ├── App.svelte              # Root layout, Wails event subscriptions
    ├── stores/satstore.js      # Svelte stores for all app state
    ├── lib/
    │   ├── wails.js            # Wails Go call bridge + dev stubs
    │   └── utils.js            # Formatting helpers (freq, az, el, etc.)
    └── components/
        ├── StatusBar.svelte    # Top bar: clock, sat data, Doppler, connections
        ├── SatSelector.svelte  # Left sidebar: search + quick-select + full list
        ├── WorldMap.svelte     # Leaflet map with sat markers + footprints
        ├── PolarPlot.svelte    # SVG polar az/el plot
        ├── PassesPanel.svelte  # Pass list + detail + embedded polar plot
        └── SettingsPanel.svelte # QTH, frequencies, FlexRadio, rotor, TLE
```

---

## Prerequisites

```bash
# Go 1.21+
# Node.js 18+
# Wails v2
go install github.com/wailsapp/wails/v2/cmd/wails@latest

# Verify
wails doctor
```

---

## Setup & Build

```bash
# 1. Clone / copy project
cd SatMaster

# 2. Download Go dependencies
go mod tidy

# 3. Install frontend deps
cd frontend && npm install && cd ..

# 4. Development mode (hot reload)
wails dev

# 5. Production build (single .exe)
wails build
# → build/bin/SatMaster.exe
```

---

## FlexRadio 8600 — Protocol Notes

SatMaster uses the SmartSDR **TCP API** on port **4992**.

Commands sent:
```
C1|slice set 0 freq=145.800000    # Set RX frequency (MHz)
C2|transmit set freq=145.200000   # Set TX frequency (MHz)
```

- Connect: Settings → FlexRadio 8600 → enter IP → Connect
- The active slice index is 0 (Slice A) by default
- Doppler correction fires every second during active tracking
- Dead-band: updates only sent when shift exceeds ~10 Hz

---

## PstRotator — Protocol Notes

SatMaster sends **UDP XML** to PstRotator on port **12000** (default).

```xml
<PST><CMD>SET</CMD><AZ>180.0</AZ><EL>45.0</EL></PST>
```

- Configure in PstRotator: Setup → UDP Server → Port 12000
- Dead-band: 0.5° Az and El to prevent rotor hunting
- Elevation is clamped to [0°, 90°] — no negative elevation commands sent

---

## TLE Data

- **Primary source:** `https://tle.oscarwatch.org/nasabare.txt`
- **Fallback:** Celestrak SOCRATES
- **Cache:** `%LOCALAPPDATA%\SatMaster\satmaster_tle_cache.txt` (Windows)
- **Bundled fallback:** ISS, AO-7, AO-27, SO-50 (always available)
- TLE age shown in status bar; highlighted orange if > 48h

---

## Pass Prediction

- Step: 10s (30s when satellite below -15° elevation)
- AOS/LOS bisection precision: 1 second
- Horizon: passes below 5° Max El are filtered from the list
- 24-hour prediction window

---

## Doppler Formula

```
f_corrected_down = f_nominal × (1 - v_range / c)
f_corrected_up   = f_nominal / (1 - v_range / c)

where:
  v_range = range rate in km/s (+ = receding, - = approaching)
  c       = 299792.458 km/s
```

---

## Keyboard Shortcuts

| Key | Action |
|-----|--------|
| `M` | Switch to Map tab |
| `P` | Switch to Passes tab |
| `S` | Switch to Settings tab |

---

## Adding More Satellites

The app loads all satellites from the TLE feed (~2000+ amateur sats from OscarWatch).
Use the search box in the satellite selector to find any satellite by name or NORAD catalog number.

Common amateur satellites available:
- ISS (ZARYA) — 145.800 MHz FM voice
- AO-7 — 145.975 MHz / 29.502 MHz linear transponder
- AO-27 — 145.850 MHz FM
- SO-50 — 436.795 MHz FM
- RS-44 — 435.640 MHz / 145.935 MHz linear
- PO-101 (Diwata-2) — 437.500 MHz FM
- XW-2A/B/C/D — CW/linear transponders
- CAS-4A/B — linear transponders

---

## Future Enhancements

- [ ] Ground track on world map (lat/lon per pass point)
- [ ] Multiple satellite tracking (split-screen polar)
- [ ] Audio squelch mute between passes
- [ ] Log4OM integration for contact logging
- [ ] Satellite database with nominal frequencies auto-loaded
- [ ] AOS/LOS audio alert
- [ ] Export pass schedule to CSV/PDF