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Jun 17, 2018, 11:49 AM
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Mini-Review

DJI Cendence Patch Antenna Test


The Patch Antenna For DJI Cendence Remote Controller











Since receiving the DJI Cendence I have seen the question time and time again asking is it worth using the DJI Patch antenna compared to the standard omnidirectional sticks and what benefit does the patch antenna give. Because of this I decided to do some tests to try and show the difference between them and see what was one was actually better to use as well as get some data on how directive the patch is as well.

For more info on the Cendence remote or the Inspire 2 or to order see
DJI Cendence http://click.dji.com/ABwjVqd-Sl9O9-w...0012&pm=custom



A Closer Look at the Patch





As you can see the patch is not just a simple passive antenna, while it has 2 RF connection it also is connected to the CAN port on the Cendence remote, because of this something to note is that the patch antenna also has firmware onboard and its important you update it when you update the remote, this is easily done by connecting the antenna to the remote before you update via DJI Go 4 or the Pilot App.











Looking inside the antenna it’s self you will find there are 2 identical PCB antennas, these are backed by a screening sheet with the logic controller board mounted in the middle. its important to ensure you have the antenna facing the correct direction as this screening sheet at the rear will block all signal from getting through so the antenna should be mounted with the smooth flat face pointing forward with the screws at the back to ensure it works correctly.











Originally when this released there was no indication of it being connected or working, the recent Cendence firmware V02.00.0090 changes this and now shows when it is connected and working via the status bar on the bottom of the main screen, you should see the below message as well getting a beep when you plug it in as long as its updated.











Something else to be aware of is if your not getting this connected message even after updating the firmware you may have a faulty patch unit and I would suggest opening a ticket with DJI Support and get it repaired if that is the case.





The Test Setup





The first issue I had was finding a way to test the antenna performance differences as its actually quite difficult to do while getting reliable results and not actually breaking any distance laws, in the end I chose to set the Inspire 2 up in a fixed position sitting on a table just over 500m the other side of a field with clear LOS. The reason I choose this method over actually flying was I wanted to be able to swap the antennas quickly without triggering RTH and also have a fixed set of conditions to try both types of antenna.













While 500m may not sound a lot to test this there was an valid reason for choosing this distance as I wanted to specifically use the 1080P live feed mode on the Inspire 2. This higher resolution live feed generally gives a lot less signal range over the standard 720P live feed and most of the time your not able to get much more than a few hundred meters in this mode so it is ideal to demonstrate the difference in antenna performance.













The Patch Directivity











I started the tests with the patch antenna fitted and I first wanted to look at the patch antennas directivity in the horizontal axis, once connected to the craft I started to rotate and it was clear the patch has a very noticeable window of 60 degrees each side of centre before the signal drops, when testing and moving the signal remained at almost 100% right up to the point of loss then it dropped off the cliff, I tested this multiple times with my phone measuring angle and it was almost 60 degrees perfect each side off centre every time.











Next I tested it in the vertical axis and this time it was a little more forgiving, with the aircraft flying above as well as with it on the table and while it appears the 60 degrees angle stands here too but I was able to stay connected more than I could in the horizontal towards the edge of the antennas field of view.





Signal Tests Patch Vs Omni Sticks





For the first signal range test I started with the patch antenna fitted with the live feed set to 1080P, I was able to get a solid full signal in all bitrates all the way up to the maximum of 10mbps in Go 4. As long as I stayed within the 60 degrees FOV of the antenna the signal remained solid and live feed was perfect with little to no breakup or drops or latency increases at all no matter if I moved the camera or not.











Next I swapped to the DJI omnidirectional stick antennas and set them in the recommended vertical rabbit ears positions, starting in 1080P at 10mbps I was not able to get a connection at all, I tried moving closer to the craft and only once I got roughly 300m away did the connection come back but it was totally unusable, at the 500m mark it was a total black out, no signal at all











Back at the 500m mark I dropped the bitrate down to 8mbps and this time it would actually connect to the craft but the feed was totally unusable, blocking and not able to hold a good connection, I was getting constant breakup and delay and it was not usable for a live feed and not something I would be happy flying with.













Dropping it to 6mbps made the connection fairly solid however there was more latency than I was getting on the patch antenna and I would normally get and any cameras movements causes blocking and the image to tear and break up, while it was usable at this point it was not ideal. Only when setting it to 4mbps was I able to get a solid connection that was similar to the patch antenna or what I would expect in normal use, after testing for several hours It was clear anything above 4mbps with the omni sticks and things stated to fall off and degrade badly.











Conclusion










I did these tests over several hours on multiple channels and it was very clear to me that the patch antenna in this situation was providing a much more stable signal in 1080P mode at the higher bitrates especially, while these tests are not perfect or 100% definitive am i’m absolutely sure that the patch antenna does give a big benefit over the omnidirectional sticks when your able to stay with in the field of view of the patch.

All of these tests were conducted in the 1080P live feed mode and I know this is something most users may not be using regularly however the results should directly translate over to the usual 720p live feed mode as well, as with all these thing thats not to say its going to result in a doubling of the signal range or even any increase when flying but I do believe the patch antenna will give better more stable live feed link overall.

One thing for sure is if your looking to use the Inspire 2 in a broadcast situation with 1080P live feed or if you just want the most stable link you can get then in my opinion you want to the use the patch antenna on the Cendence if you can, in these tests it allowed me to get to the full 10mbps data rate without issue and in all the time I have been using it I have always had no reason to doubt it .






For more info on the Cendence remote or the Inspire 2 or to order see below



DJI Cendence http://click.dji.com/ABwjVqd-Sl9O9-w...0012&pm=custom



DJI Inspire 2 http://click.dji.com/AMpk6Ct55_9nJaf...0012&pm=custom








Please note the above are affiliate links.





Last edited by Mad_angler1; Jun 17, 2018 at 02:56 PM.
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