Herelink testing and issues

HereLink
1

Hello!
I tested the herelink a few days ago (ootb firmware) through a very populated urban area, with a bit of elevation change. The source video was from a computer. The transmitted lag was about 120 msec, and we were impressed with the quality (shout-out to CubePilot for making one of the first high quality feature packed hd fpv systems). We were able to achieve about a mile and a half of range, which is reasonable considering the amount of blockage to any kind of LOS.

As a few people mentioned that the Flir Vue Pro HDMI module (built for lightbridge/solo) did not work, I began testing a few alternative modules today. In addition, I was going to update to the latest firmware; however, weā€™ve run into an issue - suddenly the air unit seems to have powered off. The air unit was being powered by a regulated 5v supply, and the air unit was roughly room temperature, so itā€™s not a overheating or power issue.
Anyone have ideas?
While I am still open to discussion, I just tested the air unit with a 2s battery I had around, and it is working properly. A multimeter showed the voltage on that bus occasionally dipping to 4.8v so I suspect the supply may have a failed regulator. An oscilloscope will tell. Stay tuned for analog to HDMI converter test results.

Update:
I have tested these two converters and can confirm they work as expected.

  • https://www.amazon.com/dp/B0771TSGVC - when viewing recorded video from the herelink frame-by-frame, this one appeared to have very slightly higher video quality but there is a significant chance that it was caused by me using a 6" cable vs the 4ā€™ ones on the other adapter.
  • Amazon.com

Update:
After some testing (to no avail) I think I have determined why the Xiaomi Yi action cams do not work with the HereLink. Regardless of what resolution and standard (NTSC/PAL) you set them to, they only output 1080i on the live feed. this may be possibly fixed by a firmware hack

Update:
I ended up using the AuviPal converter (second link) because it, when disassembled has a much smaller PCB (weighing in at 7g). Picture is in the thread below.

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@philip Do you know what impedance and series the antenna connectors are for the ground unit? I would like to get some extension cables for the antennas as the position we are likely to have the herelink in is not optimal for LOS with the drone.

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50ohm, nothing special :slight_smile:
Connector is mentioned in the manual, unfortunately I donā€™t have that with me right now

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I recall it saying that the air unit used MMCX, but I donā€™t think it mentioned the connector for the ground unit. They look like Mini BNC/ High Density BNC but I think those are only available in 75ohm. If you can check whenever it is convenient for you, Iā€™d appreciate it.

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Hi, we have tested an av to hdmi converter the same as your first link to ā€œCIMPLE COā€ unit. It seems to come in many brands and colors. You have to be carefull when ordering one as the same unit comes in different configurationsā€¦eg you can easily select an HDMI to AV instead of the other way aroundā€¦
I thought the herelink air unit was supposed to run on 12v?

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A 2s battery is the ideal power source
Absolute minimum is 5.0v, not 4.9ā€¦ max is a fully charged 3sā€¦ which is about 12.6V

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Hi,
Sorry for my ignorance, whatā€™s the meaning of ā€˜ootbā€™ firmware? As Iā€™m using the latest firmware and not able to get the Herelinkā€™s lag lower than 230ms. Any advice on how I could achieve 120ms like yours. Thank you.

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OOTB means just Out of the box

Google very often can help and answer immediately, why markice donā€™t you ask it, as first attempt?

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For those wondering, here is the image of the disassembled converter:

IMG_20190908_150308%20-%20Copy
IMG_20190908_150308 - Copy.jpg4160Ɨ3120 2.23 MB

I am a bit curious as to the usefulness of the RX/TX pads on the upper left side of the pcb

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Mark, are you including the cameraā€™s latency in that measurement?

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@philip Were you able to check on the ground unit RF connector type (see my earlier reply)?

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Mini BNC

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What the chip reference?

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@philip 50 or 75 ohm? Iā€™ve sound suppliers for both. Thanks

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Donā€™t remember off the top of my head, I took some high-res images of the PCB I will post.
Edit: @Julien here is the image:

IMG_20190923_203032%20-%20Copy
IMG_20190923_203032 - Copy.jpg4160Ɨ3120 2.77 MB

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50

17

Thanks, I have some cables on order. I appreciate you taking the time to answer that.

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@MadeByMan could you please share your supplier for the controller antenna cables/connectors?

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Can anyone find the chip real life reference ?

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Iā€™ve gone through a handful of websites searching, but couldnā€™t line it up with any datasheet/pinout. If I ever find out, Iā€™ll let you know/post it here

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