P4 - poor range

[PaulSouthport]

Hi all

I bought a 2nd hand P4 recently. Perfect condition, checked flight logs, all looks good, not many cycles on the batteries. Was on the previous FW.

I flew it in a couple of places where my P3A would easily hit 3km + (out over the marshes where no one dares to go), and I get between 300m and 800m before a sudden loss of signal and RTH. Simply won't go beyond 800m and takes careful adjustment of altitude and antennas to keep a signal - but eventually it just drops off and RTH. During RTH with Phantom facing me signal is worse and drops more often.
There are no radio towers, or wifi sources nearby.

I updated the FW in the vain hope it would improve the range. It didn't. Everything else is great, but range is still like a P3S.

I'm assuming this isn't normal.... I'm also assuming it may be a bad antenna in the Phantom, more likely than in the radio - I think.

Any thoughts or tests I could run to pin point the problem?

Some examples:
Airdata UAV - Flight Data Analysis for Drones
Airdata UAV - Flight Data Analysis for Drones
Airdata UAV - Flight Data Analysis for Drones

EDIT: Another clue (perhaps)
Just been out for another test. If I touch the left antenna when the Phantom is more than a few meters away I can instantly cause a total signal loss (control and video). Is this normal on P4? I never experienced it on my P3A

 

[Deleted member 62848]

Hi all

I bought a 2nd hand P4 recently. Perfect condition, checked flight logs, all looks good, not many cycles on the batteries. Was on the previous FW.

I flew it in a couple of places where my P3A would easily hit 3km + (out over the marshes where no one dares to go), and I get between 300m and 800m before a sudden loss of signal and RTH. Simply won't go beyond 800m and takes careful adjustment of altitude and antennas to keep a signal - but eventually it just drops off and RTH. During RTH with Phantom facing me signal is worse and drops more often.
There are no radio towers, or wifi sources nearby.

I updated the FW in the vain hope it would improve the range. It didn't. Everything else is great, but range is still like a P3S.

I'm assuming this isn't normal.... I'm also assuming it may be a bad antenna in the Phantom, more likely than in the radio - I think.

Any thoughts or tests I could run to pin point the problem?

Some examples:
Airdata UAV - Flight Data Analysis for Drones
Airdata UAV - Flight Data Analysis for Drones
Airdata UAV - Flight Data Analysis for Drones

EDIT: Another clue (perhaps)
Just been out for another test. If I touch the left antenna when the Phantom is more than a few meters away I can instantly cause a total signal loss (control and video). Is this normal on P4? I never experienced it on my P3A

Hi never really tested my stock i think used to fly out over 5000ft so was probly ok but did upgrade just to avoid the issue,done hands on just now and looking at antenna there aint much under plastic,the plastic mayby blocking half the signal,heres a pic of inside antenna,no wonder some are good and bad

bit strange how you touch and loses signal ay ,mayby soilder came unstuck where it goes on this board

 

[PaulSouthport]

Thanks ianzone, does the plastic shroud pop off? I'll take a look later tonight. Haven't found a uk seller of antenna yet and want to stick with stock DJI parts for now

 

[grin factor]

Don't have the answer, but its not right.
Did you ask the person you bought it from about this?

 

[Deleted member 62848]

Thanks ianzone, does the plastic shroud pop off? I'll take a look later tonight. Haven't found a uk seller of antenna yet and want to stick with stock DJI parts for now

 

[PaulSouthport]

Grin factor, I did, but no response as of yet.

Ianzone - you should freelance doing illustrations for DJI manuals! Thanks

 

[tevek]

Grin factor, I did, but no response as of yet.

Ianzone - you should freelance doing illustrations for DJI manuals! Thanks

Well from my experience, that's how Ian rolls! Always helpful and obviously from New Zealand. They invent stuff and flog us in rugby....
Your distances stock are pretty ordinary unless there is an antenna issue. Stock for me was about 3000 mtrs and now 5500+ mtrs with the boosted mod. Pretty sure you can't buy the antenna separately as I donated my old ones to a chap who snapped one of his off and couldn't find spares as a listed part. @John Locke has done extensive tests on the GL300C and has some testing info using a variety of devices (he does not rate these controllers at all). Regardless, your distance in an open, inteference free area should exceed that which you are seeing. Unless you have an antenna issue in one of the phantom legs or is lose inside the shell. Can you borrow another controller to test and eliminate one or the other.

 

[PaulSouthport]

I may have a GL300A on the way, which will be a useful test.
Can't find any stock antennas anywhere..... why on earth is that not a replacement part from DJI?
If I were to buy replacement antennas, I'm not looking for powered stuff, I need to stay within the UK law. I also would like to be able leave them attached in my flight case. I see many on ebay ranging from around £16 upwards. What should I be looking for to ensure a decent P4 experience. I'm not looking to set any records, if I could get to 2500m without signal loss I'd be happy (despite getting over 4000m on my stock P3A). It's not so much the absolute range, I want to know that I won't get signal loss within 1000m, and am able to rotate for photos etc. without a sudden RTH

 

[Deleted member 62848]

I may have a GL300A on the way, which will be a useful test.
Can't find any stock antennas anywhere..... why on earth is that not a replacement part from DJI?
If I were to buy replacement antennas, I'm not looking for powered stuff, I need to stay within the UK law. I also would like to be able leave them attached in my flight case. I see many on ebay ranging from around £16 upwards. What should I be looking for to ensure a decent P4 experience. I'm not looking to set any records, if I could get to 2500m without signal loss I'd be happy (despite getting over 4000m on my stock P3A). It's not so much the absolute range, I want to know that I won't get signal loss within 1000m, and am able to rotate for photos etc. without a sudden RTH

Yes lots on ebay ,had same issue what to buy,ended up spending bit more and got one of these175 us $290 to nz, i dont set distance records but good to know can have short or long flight with trouble free transmission,not had a rth since fitted,very good,,took about 1 hour to install but happy with result,,i gave up on the real cheap stuff,all looks good but normaly get what we pay for,,happy hunting and flying

 

[PaulSouthport]

Thanks Ianzone.
Unfortunately, the GL300A deal fell through, so will have to keep looking. Difficult to test in NW UK at the moment - evenings are getting dark sooner and winds are up.
I've been watching MaxxUAV vids today, some great engineering going on there. But before I try to increase range, I want to prove to myself, at least, that the stock P4 is capable of a half decent range.
If only I hadn't bought that shiny new huge 4K TV I'd still be happily flying my P3A

 

[PaulSouthport]

Today I tried using custom channels and 4MP transmission. There was no discernible difference - very flaky reception and total loss/RTH multiple times.
On the plus side, it illustrated the precision landing -

A new set of legs arrived this morning. A qiuck inspection of the existing legs shows all antenna are connected to their cables, at least at the leg end.
Also, the awesome Jack at Heliguy has found a set of transmitter antennas for me.
I'm hoping either one of those will fix this, this Phantom is pretty crap as it is.

Airdata UAV - Flight Data Analysis for Drones

 

[Erised]

Looking at your data it does seem as a antenna problem because you where in what looks to be a very clear area. Lost connections for over 20 seconds at times is lots. I have maxxuav dbs2 not boosted and I really like them.

 

[PaulSouthport]

Experiment time......

 

[Deleted member 62848]

Experiment time......

Looks good new parts ​

 

[PaulSouthport]

Replaced the transmitter antennas, and the legs on the P4.
No change, still signal loss at 500m with the occasional longer flight, out to a max of 1000m.
RF quiet area, where my P3A would do 3000m and more. As far as I remember, the P3A only had 1 auto RTH in the 150 or so flights I did.
This P4 does RTH at least once per flight.

Next step, find another transmitter to bind to.....

 

[Deleted member 62848]

Replaced the transmitter antennas, and the legs on the P4.
No change, still signal loss at 500m with the occasional longer flight, out to a max of 1000m.
RF quiet area, where my P3A would do 3000m and more. As far as I remember, the P3A only had 1 auto RTH in the 150 or so flights I did.
This P4 does RTH at least once per flight.

Next step, find another transmitter to bind to.....

Hi bloody thing got mind of its own ,before i did my upgrade i used to get a lot rth with dji ,have a go on litchi app i fly both and find for some reason litchi seems bit more stable for me ,only had 1 rth which i cancelled and continued with flight,it might like litchi ,

 

[PaulSouthport]

Yes, I tried Litchi, same result as Go.
Could do with testing the RF output, but may just send it off to a DJI authorised repairer, they'll diagnose it for about £40.

 

[Deleted member 62848]

Yes, I tried Litchi, same result as Go.
Could do with testing the RF output, but may just send it off to a DJI authorised repairer, they'll diagnose it for about £40.

Wow thats a bummer ay,something goin on there,after see new antennas i thought you be away ,the joys of drones,only trouble with secondhand hand things we dont know what we in for,hope you get a fix ,the p4 when going normal is quite a good bird,i can say i fly mine more than me others,best of luck ,thinking on this if i find something i post it

 

[PaulSouthport]

Cheers, I'm almost tempted to stick a new one on the credit card and sell this one, but I couldn't sell it in good conscience until it's working as expected.