Hi! I was able to take my drone out yesterday after only a few runs under my belt (just built it, and the snow is finally gone) and something happened on one of my last packs. The RSSI went from 30->0 instantly.

Here's a video on my youtube. The fall is at 2minutes


As you can see, the RSSI drops lower as I pass some trees, but for the most part it manages to be ok and gets stronger as I fly higher. Then as I pass myself (sitting with TX on my lap), it seems to be affected, but ok... and then boom. 34 -> 0

I have a Spektrum DX6 transmitter with a SPM4650 micro receiver. The small antenna are sticking out the back, roughly 90 degrees to eachother. 


Might this be a wiring issue between the transmitter and FC? Thanks in advance.

RSSI below 35 is in the failsafe danger zone and is when you can expect a failsafe to kick in which is exactly what happened, so always keep an eye on RSSI because yours drops quite low at more than one point in the video.

I notice that the RSSI drops whenever you turn the quad to face you. With the antennas on the back of the quad like that. the carbon frame is likely blocking the RF signal. I would try to relocate the antennas so they get a clearer line of sight to the transmitter. Some people have them sticking out from the arms shrink wrapped to cable ties to stop them flapping around. That is the other issue I see with yours. They just appear to be wires sticking out with no kind of support.

Also, is your Spektrum DX6 the one with the dual antennas?

(27-Apr-2020, 06:37 PM)SnowLeopardFPV Wrote: RSSI below 35 is in the failsafe danger zone and is when you can expect a failsafe to kick in which is exactly what happened, so always keep an eye on RSSI because yours drops quite low at more than one point in the video.

I notice that the RSSI drops whenever you turn the quad to face you. With the antennas on the back of the quad like that. the carbon frame is likely blocking the RF signal. I would try to relocate the antennas so they get a clearer line of sight to the transmitter. Some people have them sticking out from the arms shrink wrapped to cable ties to stop them flapping around. That is the other issue I see with yours. They just appear to be wires sticking out with no kind of support.

Also, is your Spektrum DX6 the one with the dual antennas?

Thank you! I found it difficult to find any sort of guidance online about best-practices when it comes to antenna placement. Just various comments here and there about the things you mentioned.

So having them "under" the arms, is that ok? Sounds like I have some re-soldering to do and move stuff around. I'll poke around rotorbuilds and look for examples of antenna placement on the squirt v2.

I do have the one with dual antennas. One on top and one perpendicular as a "handle".

By under the arms I mean like in the image below. This generally gives better line of sight to the antennas from the ground when it's up in the air. An alternative is to put them in tubes on the top or back of the quad at an angle so there is some line of sight to part of the antennas in most cases.

With a freestyle or racing quad that is continually changing pitch and roll rotation, most of the time the antennas will be in view of the transmitter, but with a Cinewhoop that generally remains in an upright position, antenna placement is more critical. The long range guys who also fly upright have theirs in long tubes sticking out the top at the back of the quad.

Keep in mind that the Spekrum RC systems have always some bad press for poor range. You might want to watch the following video you haven't already seen it: https://youtu.be/P-Dfw_qtdys?t=0

Here are a few examples of antenna placement...

I have both the configuration like in the first image and with L shape that is similar to the V shape ones on the back of the quad.
In my experience the L or V shape on the back of the quad gives a little more reception capabilities. I tend to have better values with that configuration. I can compare them directly because both receivers are FrSky XSR. Either way, I don't get even close to the announced 1,5km range. On 500meters I'm already close to the danger zone.
If you already have bad reception on close range I would go with any of the last 3 examples Snow showed.

Thank you for the pictures, advice, and video link. My dad bought me the DX6 transmitter for my birthday, so it's the first tx/rx combo I am going to go with it. I'd hate to sell it any time soon because it "sucked" compare to others I'll work on aligning my antenna's to be sticking up more and away from the frame like in the pictures and let you know how it goes. I should do a range test on my drone too and walk around various points to test.

Actually, quick question that I've read little about: is the important part on the diversity antennas the little un-shielded part at the end? Can the grey part bend a bit to go around a post for example? Just keep the little end straight and far away from the frame/electronics? Thanks.

The active end part of the antenna is the most important bit, but you should also try to avoid any tight bends in the cable to minimise signal loss. Ronin posted a good summary of some of the things that can have an impact on the signal strength in the following thread...

https://intofpv.com/t-antenna-efficacy-with-bends-adapters-etc

(28-Apr-2020, 12:56 AM)SnowLeopardFPV Wrote: The active end part of the antenna is the most important bit, but you should also try to avoid any tight bends in the cable to minimise signal loss. Ronin posted a good summary of some of the things that can have an impact on the signal strength in the following thread...

https://intofpv.com/t-antenna-efficacy-with-bends-adapters-etc

Before I put it all back together, is this the general idea? I put a zip tie off the back and one straight up the top. I'll clip the tie length, then shrink-tube or electrical tape the antenna's to the ties.

Added a new image (with :beer: of course). Moved the top one over so the battery can fit.

You will be fine with a Spektrum radio.  I've been flying a DX7S for 8 years now.  I have never experienced range issues or failsafes with Spektrum receivers.  Just re-orient your antennas 45 degrees to perpendicular to the carbon frame like others have mentioned and you will be fine.

Tonight I got to test it out (sorta, because it was windy). I put my drone with the new antenna orientation on the ground and walked 30 paces away. I then used my DX6 radio "range test" mode to reduce the power and viewed the RSSI in my goggles. The number went down to 5! I ran back to the drone and rotated it a bit and was able to get a bit better value (around 15) again at 30 paces and reduced power.

I am not impressed and am starting to wonder if I have a bad Receiver?

(29-Apr-2020, 03:07 AM)warezmonkey Wrote: Tonight I got to test it out (sorta, because it was windy). I put my drone with the new antenna orientation on the ground and walked 30 paces away. I then used my DX6 radio "range test" mode to reduce the power and viewed the RSSI in my goggles. The number went down to 5! I ran back to the drone and rotated it a bit and was able to get a bit better value (around 15) again at 30 paces and reduced power.

I am not impressed and am starting to wonder if I have a bad Receiver?

The first suggestion I would make is to re-seat the antennas by unplugging and re-plugging the IPEX connectors, and while you have them unplugged, use a magnifying glass to check the sockets for any damage. Also, check the antennas for any obvious damage to the coaxial shielding.

Failing that, replacing the receiver would be the next cheapest option. Maybe it would even be worth getting a different receiver altogether. I'm afraid I have no hands-on experience with the Spektrum gear so maybe Sugs might be able to suggest an alternative receiver that might be better, if there is a better one that is.

Definitely do what snow says and check your antennas.  Admittedly I have no experience with your specific receiver, so it may be worth a call to Horizon tech support to see what they think.  I personally hate IPEX, because they can easily be misaligned when you are trying to attach them, and they seem to loosen up over time and can look attached when they aren't.  Any kinks in the antenna is bad, because it might be broken.  I also like to hot glue anything IPEX, once I know the connector is fully seated.

Thanks for the help. So far so good. I was concerned by one of my antennas, so I bought some spares from my local hobby store (thank you curbside pickup!) and replaced them. I also modified their position to stick out the back. I did my range test again and got only 50 RSSI with a direct line of sight to the quad. This was with it pointed at me. I am concerned about the signal when it's flying towards me, so we'll see how this goes in the air next time I test it.

That sounds better, and those antennas are in a better position now, but of course it depends how far away from the quad you where when you got 50 RSSI. What was the approximate distance between the quad and your transmitter?