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Add Starlight documentation site (32 pages, 9 sidebar groups)

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Astro 5 + Starlight 0.37 site at site/ with teal/steel theme.
Content sourced from 14 reverse engineering docs, master reference,
and custom firmware source. Includes Tabs, Badge, Steps, Aside,
FileTree, and CardGrid components throughout. DiSEqC SVGs with
click-to-zoom via starlight-image-zoom. All internal links validated.
Pagefind search indexes all 32 pages.
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---
title: RF Specifications
description: RF input parameters, LNB voltage and current limits, and symbol rate range for the SkyWalker-1.
---
import { Aside } from '@astrojs/starlight/components';
## RF Input Parameters
| Parameter | Value |
|-----------|-------|
| IF frequency range | 950 -- 2150 MHz |
| Symbol rate | 256 Ksps -- 30 Msps |
| Input connector | IEC F-type female |
The IF frequency is the intermediate frequency after LNB downconversion. The host computes it as `(RF_freq - LO_freq) * multiplier` and sends it in the [TUNE_8PSK](/bcm4500/tuning-protocol/) command payload.
## LNB Power Supply
| Parameter | Value |
|-----------|-------|
| LNB voltage (standard) | 13V / 18V |
| LNB voltage (boosted) | 14V / 19V (with USE_EXTRA_VOLT) |
| Maximum continuous current | 450 mA |
| Maximum burst current | 750 mA |
<Aside type="caution" title="Current Limits">
750 mA is the maximum **non-continuous** (several minutes) allowable load. To avoid overheating the on-board voltage regulator, do not exceed **450 mA** for permanent load. Exceeding these limits may damage the SkyWalker-1 hardware.
</Aside>
LNB voltage is controlled via GPIO P0.4 on all firmware versions. The voltage selection determines the polarization:
| wValue | Voltage | GPIO P0.4 | Polarization |
|--------|---------|-----------|-------------|
| 0 | 13V | LOW | Vertical / Circular-Right |
| 1 | 18V | HIGH | Horizontal / Circular-Left |
The USE_EXTRA_VOLT command (0x94) enables a +1V boost for long cable runs by toggling bit 3 of the LNB control register at XRAM 0xE0B6 (0x62 = normal, 0x6A = boosted). See [Vendor Commands](/usb/vendor-commands/) for the command interface.
## Switch Control
The SkyWalker-1 supports multiple satellite switching protocols:
| Protocol | Implementation | Command |
|----------|---------------|---------|
| 22 kHz tone | GPIO P0.3 gates external oscillator | SET_22KHZ_TONE (0x8C) |
| Tone Burst (mini DiSEqC) | Timer2-based carrier gating | SEND_DISEQC_COMMAND (0x8D) |
| DiSEqC 1.0 | Timer2 Manchester encoding | SEND_DISEQC_COMMAND (0x8D) |
| DiSEqC 1.2 | Timer2 Manchester encoding | SEND_DISEQC_COMMAND (0x8D) |
| Legacy Dish Network | 7-bit serial bit-bang on P0.4 | SET_DN_SWITCH (0x8F) |
## 22 kHz Tone
The 22 kHz tone signal is generated by an external oscillator on the PCB, gated by GPIO P0.3. The firmware does not generate the 22 kHz carrier directly -- it only enables or disables the oscillator output.
| wValue | State | GPIO P0.3 | Band Selection |
|--------|-------|-----------|------|
| 0 | OFF | LOW | Low band (9.75 GHz LO on universal LNB) |
| 1 | ON | HIGH | High band (10.6 GHz LO on universal LNB) |
## Signal Path
```
Satellite
|
v
[ LNB on Dish ] <-- 13V/18V + 22kHz from SkyWalker-1
|
| Coax (950-2150 MHz IF)
v
[ SkyWalker-1 F-connector ]
|
v
[ BCM4500 Demodulator ] -- demod + FEC decode
|
| 8-bit parallel MPEG-2 TS
v
[ FX2 GPIF Engine ] -- zero-copy DMA to EP2
|
| USB 2.0 High-Speed Bulk
v
[ Host PC ]
```
The USB/GPIF data path has substantial headroom over the satellite link throughput:
| Metric | Value |
|--------|-------|
| USB 2.0 HS bulk (practical) | ~280 Mbps (~35 MB/s) |
| GPIF engine (theoretical) | 48 MHz x 8 bits = 384 Mbps |
| Typical DVB-S TS rate | 1--5 MB/s |
| Maximum symbol rate (30 Msps) | ~58 Mbps |
The bottleneck for all supported modulation modes is the satellite link, not the USB data path.