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Trying to troubleshoot short range with 5Ghz FPV setup.

Discussion in 'Phantom 2 Discussion' started by krb, Jan 19, 2014.

  1. krb

    krb

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    On the Phantom, I have a Zenmuse/Gopro combo + mini iOSD + generic Boscam TS351 200mW 5.8Ghz transmitter. On the ground, I'm using the Black Pearl all-in-one. I'm using the BlueBeam Ultra antenna set.

    On the ground from about 5-10 feet away I've got an ok signal, but some sort of visible ghosty lines moving through picture. After takeoff, once I get maybe 150 feet away the picture gets REALLY crap, pretty unusable. It mostly flickers but I can see the rough shape of things. It's nowhere near good enough to read the OSD unless I let the let the Phantom hover and then concentrate for few seconds. Even then, it's a crapshoot. Forget trying to see a picture. All this is line of sight, at about an 100 feet up and about 100 feet out. So far I'm testing on my street, so there are houses and such around.

    This feels like an unreasonably short distance for this gear. I'm pretty sure it's not the wiring. Today I re-did the connectors and soldered the wiring for real. It's still not perfect, so I could be loosing signal or picking up interference there, but it doesn't feel like the problem.

    I've tried various antenna positions, and I today borrowed a 3-turn helical (also circularly polarized). The helical shows a better signal at the same distance. So that's good sign, but I didn't expect to need 7dBi gain antenna to make this work out to 150 feet. I expected to go 1000 feet away and still frame a shot. I'm using more antenna connectors than I would like (RP-SMA to SMA on the tx and the receiver) so there's some loss there. I'm wondering if the problem is the transmitter.

    Have others had luck with the generic 200mW Boscam gear? Do I need 500 or 600mW? Would going to an ImmersionRC tx help? Any other tips? Do I need to be careful about shielding the connections on the Phantom? It's all kind of jammed in there with the mini iOSD and TX stuck to the bottom of the Phantom behind the gimbal.

    I'm really frustrated, any help would be appreciated.
     
  2. ianwood

    ianwood Taco Wrangler
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    Have you flown in different locations? Is it the same in each location? Have you tried different frequencies? Also, make sure you have the right antenna connectors. An RP-SMA male connector can fit on an SMA female connector but will not have any center pin to make contact and thus will give horrible results.
     
  3. krb

    krb

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    Thanks for replying.

    I thought to myself "Of COURSE I have the right connectors!". But since I asked for help and we're all idiots sometimes, I double checked this morning. I do have the right connectors. I've got male RP-SMA (threaded posts with a pin) on both the TX and the RX. I have SpiroNet antennas that fit these, and BlueBeam antennas that are SMA. I have the appropriate adapters. I double checked all the pins and sockets and it all works.


    When I posted, I had only flown on my street. Today, I flew at a local park. Wide open field. Both the docsTS351 TX and the Black Pearl RX agree that Band A ch. 4 is 5805MHz.

    At the park, I tried no camera, just the output from the mini iOSD to the transmitter. According to the OSD, I got 20m out and 19m up before some pretty serious flicker.


    Sort of. I wanted to test the RX against someone else's transmitter so I asked a guy at the field if I could listen in. He gave me the channel, I found it on the RX and watched him go. He said he was a 300+ meters away and I could see his signal pretty well. As expected, I lost it when he went behind some trees, but otherwise the whole thing was what I expected with my setup when I bought everything. He claimed to be using a 200mW TX on 5880MHz. It had a small cloverleaf-style omni on it. I think the receiver is fine.

    As a last ditch effort, I tried leaving the TX on "5805" and tuned the RX to different channels on different bands. I got a pretty good signal on Band F channel 5, which is supposed to be the Airwave band. According to the Black Pearl manual, this is supposed to be 5820MHz. I flew my Phantom with this and got out to almost 50m. I then put on my 7dBi helical and could get out to 100m before seeing severe flicker.

    I don't have access to anything like a spectrum analyzer, but I'd really like to see what freq the TX is centered on for each channel setting it has (1-8) and also how much power it's sending to the antenna. Given that I get better reception on 5820, I suspect the TX is either mislabeled or somehow "off" or defective. 5820 is close to Band A ch. 3 (5825) so I tried that on the RX and I got just ghosting and static. I again verified the position of the dip switches on the RX, it's set to ch 4 (TX only does band A)

    Talking to several people at the field, they expected I should see better range given the antennas and the TX power. I'd like to avoid a 600mW TX, but maybe that's the way to go.