skywalker-1/site/src/content/docs/tools/tuning.mdx

---
title: Tuning Tool
description: DVB-S tuning, signal monitoring, LNB control, DiSEqC switching, and transport stream capture.
---

import { Tabs, TabItem, Steps, Aside, Badge } from '@astrojs/starlight/components';

`tune.py` is the primary user-facing tool for operating the SkyWalker-1 as a satellite receiver. It handles the complete signal chain: powering the demodulator, configuring LNB voltage and tone, sending DiSEqC switch commands, tuning to a transponder, monitoring signal quality, and capturing MPEG-2 transport stream data.

```bash
pip install pyusb
```

## Subcommands

| Subcommand | Purpose |
|------------|---------|
| `status` | Show device config, firmware version, and signal info |
| `tune` | Tune to a transponder frequency |
| `stream` | Capture MPEG-2 transport stream data |
| `diseqc` | Send DiSEqC switch commands |
| `lnb` | Control LNB voltage and 22 kHz tone |

Running with no subcommand defaults to `status`.

## Global Options

| Flag | Description |
|------|-------------|
| `-v, --verbose` | Show raw USB control transfer traffic |
| `--json` | Output machine-readable JSON (where supported) |

---

## status -- Device Information

Displays the current device state: firmware version, configuration status flags, signal lock, and SNR.

```bash
sudo python3 tools/tune.py status
```

```
Genpix SkyWalker-1 Status
==================================================

USB: Bus 1 Addr 12 (VID 0x09C0, PID 0x0203)
FW:  2.06.4 (built 2007-07-13)

Config: 0x07
  [ ON] 8PSK Started
  [ ON] BCM4500 FW Loaded
  [ ON] LNB Power On
  [off] DVB Mode
  [off] 22 kHz Tone
  [off] 18V Selected
  [off] DC Tuned
  [off] Armed (streaming)

Signal Lock: LOCKED
SNR:         8.2 dB (raw 0x0823)
Quality:     [################------------------------] 42.3%
```

Use `--json` for programmatic access to all fields.

---

## tune -- Transponder Tuning

The 8-step tuning sequence: check status, boot demodulator, enable LNB power, set voltage (polarization), set extra voltage, set 22 kHz tone (band), send TUNE_8PSK command, wait for signal lock.

### Required Arguments

| Argument | Description |
|----------|-------------|
| `FREQ` | Transponder downlink frequency in MHz (e.g., `12520`) |
| `SR` | Symbol rate in ksps (e.g., `27500`) |

### Options

| Flag | Description |
|------|-------------|
| `--pol H/V/L/R` | Polarization: H (horizontal/18V), V (vertical/13V), L (left circular/18V), R (right circular/13V) |
| `--band low/high` | LNB band: low (tone off, 9750 MHz LO) or high (tone on, 10600 MHz LO) |
| `--lnb-lo MHZ` | Override LNB local oscillator frequency (default: 9750 low, 10600 high) |
| `--mod TYPE` | Modulation type (default: `qpsk`) |
| `--fec RATE` | FEC rate (default: `auto`) |
| `--timeout SECONDS` | Signal lock timeout (default: `10`) |
| `--extra-volt` | Enable +1V LNB voltage boost for long cables |
| `--json` | Output JSON result |

### Modulation Types

| Name | Description | FEC Group |
|------|-------------|-----------|
| `qpsk` | DVB-S QPSK | dvbs |
| `turbo-qpsk` | Turbo-coded QPSK | turbo |
| `turbo-8psk` | Turbo-coded 8PSK | turbo |
| `turbo-16qam` | Turbo-coded 16QAM | turbo-16qam |
| `dcii-combo` | Digicipher II Combo | dcii |
| `dcii-i` | Digicipher II I-stream | dcii |
| `dcii-q` | Digicipher II Q-stream | dcii |
| `dcii-oqpsk` | Digicipher II Offset QPSK | dcii |
| `dss` | DSS QPSK | dvbs |
| `bpsk` | DVB BPSK | dvbs |

### FEC Rates by Group

| Group | Available Rates |
|-------|----------------|
| **dvbs** | `1/2`, `2/3`, `3/4`, `5/6`, `7/8`, `auto`, `none` |
| **turbo** | `1/2`, `2/3`, `3/4`, `5/6`, `auto` |
| **turbo-16qam** | `3/4`, `auto` |
| **dcii** | `1/2`, `2/3`, `6/7`, `3/4`, `5/11`, `1/2+`, `2/3+`, `6/7+`, `3/4+`, `auto` |

<Tabs>
<TabItem label="DVB-S">

```bash title="Standard DVB-S QPSK, Ku-band high"
sudo python3 tools/tune.py tune 12520 27500 --pol H --band high
```

```bash title="DVB-S with explicit FEC"
sudo python3 tools/tune.py tune 11836 27500 --pol V --band low --fec 3/4
```

```bash title="C-band with custom LNB LO"
sudo python3 tools/tune.py tune 3960 26667 --pol V --lnb-lo 5150
```

</TabItem>
<TabItem label="Turbo">

```bash title="Turbo 8PSK"
sudo python3 tools/tune.py tune 12224 20000 --pol V --band high --mod turbo-8psk --fec 2/3
```

```bash title="Turbo QPSK with auto FEC"
sudo python3 tools/tune.py tune 12090 20000 --pol H --band high --mod turbo-qpsk
```

</TabItem>
<TabItem label="DCII">

```bash title="Digicipher II Combo"
sudo python3 tools/tune.py tune 12224 20000 --pol V --band high --mod dcii-combo --fec auto
```

```bash title="DCII Split I-stream"
sudo python3 tools/tune.py tune 12224 20000 --pol V --band high --mod dcii-i --fec 6/7
```

</TabItem>
</Tabs>

### Tuning Output

```
Tuning SkyWalker-1
==================================================
  Downlink:     12520 MHz
  LNB LO:       10600 MHz
  IF Frequency:  1920.0 MHz (1920000 kHz)
  Symbol Rate:   27500 ksps (27500000 sps)
  Modulation:    DVB-S QPSK (index 0)
  FEC:           auto (index 5)
  Polarization:  Horizontal (18V)
  Band:          high (22kHz on)

[1/8] Config status: 0x07
[2/8] Demodulator already running
[3/8] LNB power already on
[4/8] Setting LNB voltage: 18V
[5/8] Extra voltage: off
[6/8] 22 kHz tone: ON
[7/8] Sending TUNE_8PSK...
[8/8] Waiting for signal lock (timeout 10s)...
...

  LOCKED
  SNR:     8.2 dB (raw 0x0823)
  Quality: [################------------------------] 42.3%
```

<Aside type="tip">
The IF frequency is computed as `downlink - LNB_LO`. It must fall within 950--2150 MHz or the tool will warn. If you see negative IF values, your LNB LO is set higher than the downlink frequency -- check your LNB type.
</Aside>

---

## stream -- Transport Stream Capture

Captures MPEG-2 transport stream data from EP2 bulk endpoint after the device is tuned and locked. Requires a prior successful `tune` command (signal must be locked).

```bash title="Capture to file for 60 seconds"
sudo python3 tools/tune.py stream -o capture.ts --duration 60
```

```bash title="Pipe directly to VLC"
sudo python3 tools/tune.py stream --stdout | vlc -
```

```bash title="Pipe to ffmpeg for recording"
sudo python3 tools/tune.py stream --stdout | ffmpeg -i pipe: -c copy output.mp4
```

| Flag | Description |
|------|-------------|
| `-o, --output FILE` | Write TS data to file |
| `--stdout` | Write TS data to stdout (for piping) |
| `--duration SECONDS` | Capture duration (default: until Ctrl-C) |

The stream status is written to stderr when using `--stdout`, so it does not contaminate the TS data pipe.

<Aside type="tip">
Capture a short sample and analyze it with [ts_analyze.py](/tools/ts-analyzer/) to verify PIDs, check for continuity errors, and identify the programs in the transport stream.
</Aside>

---

## diseqc -- Switch Commands

Send DiSEqC 1.0 port selection, mini-DiSEqC tone bursts, or raw DiSEqC messages.

```bash title="Select DiSEqC 1.0 port 1"
sudo python3 tools/tune.py diseqc --port 1
```

```bash title="Send tone burst A"
sudo python3 tools/tune.py diseqc --tone-burst A
```

```bash title="Send raw DiSEqC message"
sudo python3 tools/tune.py diseqc --raw E0 10 38 F0
```

| Flag | Description |
|------|-------------|
| `--port 1-4` | DiSEqC 1.0 committed switch port |
| `--tone-burst A/B` | Mini-DiSEqC tone burst |
| `--raw HH HH ...` | Raw DiSEqC bytes in hex (3--6 bytes) |

For details on the DiSEqC signaling implementation, see [DiSEqC Protocol](/lnb-diseqc/diseqc-protocol/).

---

## lnb -- LNB Control

Direct control of LNB voltage, 22 kHz tone, and power supply. Running with no flags shows the current LNB state.

```bash title="Show LNB status"
sudo python3 tools/tune.py lnb
```

```bash title="Set voltage and tone"
sudo python3 tools/tune.py lnb --voltage 18 --tone on
```

```bash title="Power cycle the LNB"
sudo python3 tools/tune.py lnb --power off
sudo python3 tools/tune.py lnb --power on
```

| Flag | Description |
|------|-------------|
| `--voltage 13/18` | LNB voltage (13V = vertical, 18V = horizontal) |
| `--tone on/off` | 22 kHz tone (on = high band, off = low band) |
| `--extra-volt` | Enable +1V boost (13V becomes 14V, 18V becomes 19V) |
| `--power on/off` | LNB power supply on/off |

<Aside type="caution">
The LNB can supply up to 750 mA non-continuous, but sustained loads should stay below 450 mA to avoid overheating the on-board regulator. Use `--extra-volt` only when needed for long cable runs.
</Aside>

---

## Signal Quality Metrics

| Metric | Source | Description |
|--------|--------|-------------|
| **SNR** | `GET_SIGNAL_STRENGTH` (0x87) | Signal-to-noise ratio in dB, read as 16-bit value (dBu * 256 units) |
| **Lock** | `GET_SIGNAL_LOCK` (0x90) | BCM4500 register 0xA4, bit 5 indicates signal lock |
| **Quality %** | Computed | SNR scaled: `snr_raw * 17` maps to 0--100%, saturating at SNR >= `0x0F00` |

For details on the signal monitoring protocol, see [Signal Monitoring](/bcm4500/signal-monitoring/).

## See Also

- [Tuning Protocol](/bcm4500/tuning-protocol/) -- firmware-level TUNE_8PSK command format
- [LNB Control](/lnb-diseqc/lnb-control/) -- hardware-level voltage and tone control
- [TS Analyzer](/tools/ts-analyzer/) -- analyze captured transport streams
- [Vendor Commands](/usb/vendor-commands/) -- complete USB command reference