Why OpenIPC’s 4Mbps Default Is Only the Starting Point

Why OpenIPC’s 4Mbps Default Is Only the Starting Point

OpenIPC does not make an ordinary Wi-Fi connection to an access point. WFB-NG sends video as a broadcast link, while the air unit’s processor encodes the camera feed. That is why an OpenIPC air unit is more than a conventional analogue VTX and why its camera, processor, radio chipset and cooling all matter.

The current OpenIPC documentation defines the baseline as 4Mbps video over a 20MHz channel, MCS 1, long guard interval and 8/12 forward-error correction. That profile favours a usable link over maximum image quality. Raising bitrate alone can make the picture look better on the bench while producing packet loss as soon as the aircraft reaches a weaker part of the link.

Adaptive Link: What It Changes

Adaptive Link removes the need to choose one fixed compromise. The ground station measures RSSI and SNR, converts them into a score from 1000 to 2000, and sends that score back to the aircraft. The air-side alink_drone process then chooses a matching row from /etc/txprofiles.conf.

Setting	Weaker-link direction	What you trade
MCS	Lower	Less throughput for more stability
Video bitrate	Lower	Less detail and fewer compression artefacts caused by an overloaded link
Guard interval	Long	Lower speed for better protection
Channel width	Narrower, where supported	Less throughput for better range

The example profile set in the official documentation moves from roughly 2Mbps at MCS 0 to 9Mbps at MCS 2 as the score improves. Those are examples, not universal presets. Power values must be set for the specific adapter, and OpenIPC warns that a profile demanding more traffic than the hardware can carry will not work.

5MHz, 10MHz or 20MHz?

This is a hardware question before it is a tuning question. OpenIPC lists 5, 10, 20 and 40MHz support for the RTL8812AU family used in some Wyvern hardware; its RTL8812EU reference lists 5, 10 and 20MHz transmission, with 40MHz receive-only. Do not copy a 5MHz “long-range” profile until you have confirmed the radio chipset and driver on both ends.

Use the official WFB-NG bitrate calculator to check whether target video bitrate, FEC, MCS and guard interval fit inside the selected link capacity. Our recommendation is to prove the default 20MHz profile first, then change one variable at a time. Narrower bandwidth is useful when link margin matters more than picture detail; it is not a substitute for sound antennas, cooling or a clean installation.

Hardware We Would Choose

For a light experimental build, the EMAX Wyvern Link Alpha 200mW keeps the air side simpler. For a 5-inch or larger aircraft, the Wyvern Link Alpha V2 800mW is the more complete option: it pairs an IMX415 camera with active cooling and supports up to 1080p at 90fps or 720p at 120fps. We would choose the V2 for development because thermal management and direct computer configuration matter more than chasing the smallest module.

The air unit still needs a compatible receiver path. The Wyvern Link Alpha RX is the direct EMAX route; an SBC ground station or supported Snapdragon Android device with the correct radio is the configurable route. Browse our FPV video systems, or compare the ownership trade-offs in our analogue vs digital FPV guide.

FAQ

Does Adaptive Link automatically find the best bitrate?

It selects from profiles you define. Poor score thresholds, unsafe power values or unrealistic bitrates remain poor settings; the automation cannot correct a bad profile table.

Is 5MHz always best for long range?

No. A narrower channel can improve link margin, but it also reduces capacity and must be supported by the radio and driver at both ends. Start with a stable 20MHz baseline before testing 10MHz or 5MHz.

Is OpenIPC a plug-and-play alternative to DJI?

Not yet. Choose it for open firmware and control over the link. Choose DJI or Walksnail when predictable setup and a polished goggle workflow matter more than experimentation.