Herelink 1.0 AirUnit to AirUnit instruction

AirUnit HDMI + GroundUnit Ethernet

Device required: -Airunit x 2 (*firmware minimum 20211229 and above) -Ethernet adapter -Installing a fan on both airunits to achieve better performance - usb otg+power cable if ethernet adapter doesn't include a method to power it

GroundUnit video out can be accessed via ethernet and MavLink is available as well. Compatible ethernet adapters are shown below:

AX88772 - Ground (not tested Airside) PLUGABLE - directly connect to OTG. Nice for the ground side.

AX88179 - Ground and Air UGREEN Ethernet Adapter for Chromecast has an additional standard USB to power on airside, cables are quite long however.

R8152 / R8153 - Airside only Cable Matters

Anker USB 3.0 - no blinky lights on the Ethernet port, maybe annoying for debugging

Note: -Upgrade both units to the latest firmware before toggling the switches. -Toggle switches both down position as default AirUnit function, firmware only can be upgraded when switches both at down position.

1. GroundUnit and AirUnit Setup

1A GroundUnit setup

  1. Upgrade AirUnits to the latest firmware.(Make sure toggle both switches at down position)

  2. Power off the GroundUnit by disconnecting the power cable (7v-12v).

  3. Remove the screws from the chassis.

  4. Herelink AirUnit v1.0 (without ethernet port) Toggle the switches as shown below to activate GroundUnit. (1 up, 2 down) Note: For Herelink AirUnit v1.1 (with ethernet port) GroundUnit activated by toggle switch (1 down, 2up)

  5. Power on GroundUnit by reconnecting the power cable (7v-12v).

1B AirUnit setup

Upgrade AirUnits to latest firmware.(Make sure toggle both switches down position)

2. Pairing

Press and hold the pairing button for 3s on both AirUnit and GroundUnit within 30s

*Once pairing is completed LED will turn solid GREEN.

3. AirUnit HDMI functionality

Once AirUnit and GroundUnit are paired, connect the 1080p/720p video source to AirUnit.

There are only 1 HDMI port available for communication between AirUnit and GroundUnit, it is marked #3 in the picture below.

4. PC setup

1. Please switch off PC’s WIFI

2. Go to control panel > Network & Internet > Network connection

3. Right click and choose properties

4. Choose “internet (TCP/IPv4)”,then click properties

5. Click “use the following IP address” and enter”

6. Click “Subnet mask” and it will give you a Subnet mask.

5. PC video setup

AirUnit video stream can be obtained through VLC, MissionPlanner or QGC

5A VLC setup

Go to Media > Open Steaming > Communication Protocol

Copy and paste : “rtsp://”

Click “Play”.Click “Play”.

5B Mission Planner


  1. Right click the HUD

  2. Select ‘Video’

  3. Select ‘Set GStreamer Source’

  4. Enter “rtspsrc location=rtsp:// latency=1 udp-reconnect=1 timeout=0 do-retransmission=false ! application/x-rtp ! decodebin3 ! queue max-size-buffers=1 leaky=2 ! videoconvert ! video/x-raw,format=BGRx ! appsink name=outsink”

  5. Press OK


  1. Open Mission Planner

  2. Set the port to 'UDPCL' (top right)

  3. Click 'Connect'

  4. Enter the IP

  5. Enter port '14552'


Setup(QGC icon at the top-left corner) > Application Settings > General > Fly View > Video Settings > Source > RTSP Video Stream

RTSP URL “rtsp://”

Go back to the main screen and video input will come out.

6. VLC Video Latency Setup

VLC latency can be adjusted via below:

Media > Open Network Stream > Network > Click “Show more options” > adjust “caching” time

Tool > Preferences > Input / Codecs > Network > Default caching policy > select “Lowest latency”

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