Herelink Audio/Voice Transmission


I want to transmit voice from rover to control panel. I can transfer video and voice by using AV2HDMI converter to HDMI(HDMI connected to monitor). When i try it with herelink i can transfer video but i cannot transfer voice. Does herelink support voice transmission? What should i do to transfer voice from rover to herelink? And is it possible to transmit voice from control panel to rover?

You could try a USB microphone

Herelink already includes 2 microphone

Although it would be neat if there were two microphones on the air end, their on the ground end. Wonder what their doing there? It could be used to transmit voice from ground to air. It would be nice if we had more information, maybe a statement on the planed uses on the units peripherals.

There are heaps of features that are available that don’t yet get used. But the controller can do Calls etc if those features get added…

Hi @philip,

It seems herelink air end use LT9611 module to transmit video. It doesnt support audio transmission. Can i mount microphone to herelink air end? Would it transmit audio with video?
It seems herelink ground end doesnt have cellular(SIMCARD) socket. Cannot i use call feature of this phone?

It’s not a phone… it uses LTE point to point, not LTE to Tower… so no, it’s not designed as a phone.

However, you can connect a 4G dongle to the USB OTG connector.

You may also be able to connect a microphone to the air unit, but you would need to set this up 100% yourself via the USB OTG and the android system.

We cannot give advice on how to do this at this point.

May I ask why you need audio?

Hello Philip,

We are working on a rover project and need to get sound of rover’s surroundings. We just want to place a microphone on the rover side and listen on the control panel.

We are using navio2 and raspberry pi for ardupilot.


You can try a microphone via USB. But you would need a Linux/Android expert to set it up

1 Like


I have not done a teardown or seen schematics for the air unit, but if it does use the LT9611, I see no reason it couldn’t transmit sound - that module supports I2S and SPDIF for digital audio.

Perhaps @philip can clarify, but I would think it could transmit audio carried by the HDMI input, so the camera would have to include it

To be honest, I don’t know, audio was never a requirement

Hello @MadeByMan,
LT9611UXC has audio support but LTC9611 doesn’t.
As you can see in the link below :

LT9611 - QFN-64 Single/Dual Port MIPI CSI/DSI to HDMI 1.4 transmitter
LT9611UXC - QFN-64 Dual-Port MIPI DSI/CSI to HDMI2.0 with Audio

That is why we are trying to transfer data over raspberry/mavlink/ any good ideas :slight_smile:

Hi Berk,
I see the issue, wasn’t sure which one they were using. If you have schematic or teardown images could you post or PM them?

As far as audio, its an issue we are looking into as well. Besides having a separate transmitter system for audio, the modified firmware supporting a USB mic would be a very clean solution, and given the low data rate for audio, should not impact video transmission much or at all. Alternatively if your video is generated on the raspberry, you could do some sort of visually embedded audio like a QR code in the corner, containing the audio for that frame of video, similar to audio-on-film. If not, depending on what you are listening for and its quality requirements (scientific/full spectrum sound recording, or just an identifying sound like a buzzer) you may be able to bury some lower bit rate, compressed audio into a mavlink message, sent from raspberry to cube, then to the herelink, then via WiFi to a pc to be decoded and played.

If you don’t mind sharing a bit about your application, maybe I can give you a more detailed suggestion. I’m open to brainstorming/bouncing ideas around, and if you do think of something please share :grin:

Hello Alex,
Sorry for the late response, I was pretty busy with another project. I think audio-on-film is a little complicated for this task. Now I am planning to add usb microphone and transfer it through gstreamer (it is already in use for h264 streaming) just need to add audio sink to airunit and gcs. Also need to change usb port capabilities of air unit.

Now I am able to explore around the air unit via adb shell but couldn’t figure out how to add new capabilities or reach the whole file system…

Any advice ??

In FCC’s website you can find out detailed pictures of both air and ground units :