WFB-ng Video Link

WFB-ng (WiFi Broadcast next generation) is the protocol the agent uses for long-range HD video. It is not standard WiFi. Instead, it broadcasts raw 802.11 frames in monitor mode with forward error correction (FEC). This gives you 10-50+ km range at 30-70 ms latency. The agent manages WFB-ng directly as the ados-wfb systemd service (the native Rust ados-radio binary). No OpenHD or other wrapper is required.

How it works

Traditional WiFi requires a two-way handshake (connect, authenticate, associate). That limits range to whatever distance both sides can reliably hear each other. WFB-ng skips all of that. The transmitter broadcasts packets one-way. The receiver picks up whatever it can hear. Key differences from standard WiFi:

	Standard WiFi	WFB-ng
Mode	Managed (STA/AP)	Monitor mode (raw injection)
Connection	Two-way handshake	One-way broadcast
Range	~100-300 m	10-50+ km with directional antennas
Latency	5-50 ms	30-70 ms
Error handling	TCP retransmission	FEC (forward error correction)
Encryption	WPA2/WPA3	Custom key-based

Hardware

WiFi adapter

The recommended chipset is the RTL8812EU (5.8 GHz, 802.11ac). It supports monitor mode and packet injection at high TX power.

Spec	Value
Chipset	RTL8812EU
TX power	Up to 29 dBm (800 mW)
Frequency	5.8 GHz
Interface	USB 2.0
Weight	~25g (module form factor)

The agent auto-detects the adapter by scanning for USB devices with the RTL8812EU vendor/product IDs.

The RTL8812EU requires a DKMS kernel driver that is not part of the mainline Linux kernel. The install script installs this driver automatically on supported boards. If you are running a custom kernel, you need to build and install the driver manually.

Antennas

The adapter’s built-in antenna works for short-range bench testing. For real flights, use external antennas:

Air side (drone): Omnidirectional dipole antenna, 3-5 dBi. The drone moves in all directions, so omnidirectional coverage is important.
Ground side: Directional patch or panel antenna, 8-14 dBi. Point it at the drone for maximum range.

With a 14 dBi directional antenna on the ground and a 5 dBi dipole on the drone, expect 20-50 km line-of-sight range depending on conditions.

Configuration

video:
  mode: "wfb"
  wfb:
    interface: ""        # Auto-detected
    channel: 149         # 5 GHz channel (149 = 5745 MHz)
    tx_power: 25         # dBm (25 = ~300 mW)
    fec_k: 8             # FEC data blocks
    fec_n: 12            # FEC total blocks (data + parity)

Channel selection

WFB-ng operates on 5 GHz channels. Choose a channel that is not congested in your area. Common choices:

Channel	Frequency	Notes
36	5180 MHz	DFS in some regions
149	5745 MHz	Default, usually clean
161	5805 MHz	Alternative
165	5825 MHz	Common FPV channel

Check your local regulations. Some 5 GHz channels require DFS (Dynamic Frequency Selection) or are restricted for outdoor use. The agent does not enforce regulatory limits. You are responsible for compliance.

TX power

The tx_power setting is in dBm. Higher power means more range but also more interference and heat. Start at 25 dBm and increase only if needed.

dBm	mW	Typical use
15	32	Bench testing
20	100	Short range (< 1 km)
25	316	Medium range (1-10 km)
29	800	Long range (10-50 km)

FEC tuning

Forward Error Correction adds redundancy to the stream. The fec_k parameter is the number of data blocks, and fec_n is the total number of blocks (data + parity). The ratio fec_k/fec_n determines how much packet loss the stream can tolerate.

fec_k	fec_n	Parity ratio	Max loss tolerance
8	12	33%	33% packet loss
4	8	50%	50% packet loss
1	2	50%	50% packet loss
8	9	11%	11% packet loss

Higher parity means more resilience but also more bandwidth overhead. The default 8/12 is a good balance for most conditions.

Key management

WFB-ng uses a shared key for stream encryption. The keys live under /etc/ados/wfb/: the air unit transmits with tx.key, and the ground station receives with rx.key. Both sides must share the matching key. When using the ADOS Ground Station (another instance of the agent in ground-station profile), the keys are generated and exchanged automatically over the local radio during pairing (see WFB Pairing). You normally never touch the key files by hand. For manual key management:

# On the air unit (drone), the transmit key is at:
cat /etc/ados/wfb/tx.key

# The matching receive key on the ground station is at:
cat /etc/ados/wfb/rx.key

Link quality monitoring

The ados-wfb service reports link statistics to the state IPC socket and REST API:

Metric	Description
RSSI	Received signal strength (dBm)
SNR	Signal-to-noise ratio (dB)
Channel	Current operating channel
Packets received	Total packets decoded
Packets lost	Total packets lost (before FEC)
FEC recovered	Packets recovered by FEC
FEC failed	Unrecoverable packet groups
Bitrate	Current stream bitrate (kbps)

View link state from the setup webapp Video or Ground Station page, Mission Control Hardware tab, or the WFB-ng REST endpoints.

Ground station pairing

The air unit (drone) runs wfb_tx to transmit. The ground station runs wfb_rx to receive. Both need to be on the same channel with the same key. When using two ADOS agents (one drone profile, one ground-station profile), channel and key synchronization happens automatically through the pairing flow. When using a standalone WFB-ng receiver (like wfb-cli or a custom setup), configure the channel and key manually on both sides.

Distributed receive on the ground

The drone always transmits with wfb_tx. On the ground side, ADOS supports three receive modes depending on the Ground Agent’s role:

direct - single-node, runs plain wfb_rx. The default.
relay - runs wfb_rx -f <receiver> to forward heard fragments over the local mesh to the receiver.
receiver - runs wfb_rx -a to aggregate fragments from its own radio plus every paired relay, then runs the same Reed-Solomon FEC combine across the merged stream.

The same WFB-ng key works across all three modes; the receiver handles dedup and FEC across the combined inputs. Read the Mesh & Distributed Receive overview and the Three Deployment Roles page for the full picture on the ground side.

Troubleshooting

No video, adapter not detected

Run lsusb and check for the RTL8812EU device. If it is present but not recognized, the DKMS driver may not have built for your kernel version. Check dmesg | grep 88x2eu for driver load errors.

Short range, weak signal

Check antenna connections. Verify TX power is set appropriately. Make sure the adapter is not USB-hub-connected (use a direct USB port for stable power). Try a different 5 GHz channel to avoid interference.

High FEC failure rate

If fec_failed is climbing, you are at the edge of range or have interference. Options: increase FEC parity (lower fec_k/fec_n ratio), reduce video bitrate, use a directional antenna on the ground, or move to a cleaner channel.

​WFB-ng Video Link

​How it works

​Hardware

​WiFi adapter

​Antennas

​Configuration

​Channel selection

​TX power

​FEC tuning

​Key management

​Link quality monitoring

​Ground station pairing

​Distributed receive on the ground

​Troubleshooting

WFB-ng Video Link

How it works

Hardware

WiFi adapter

Antennas

Configuration

Channel selection

TX power

FEC tuning

Key management

Link quality monitoring

Ground station pairing

Distributed receive on the ground

Troubleshooting