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5.8GHz or 1.2GHz for vtx?

Discussion in 'FPV (First Person View)' started by golgotha, May 14, 2014.

  1. golgotha

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    I understand that this forum is more or less dedicated to DJI gear and quads in general, however I've noticed that folks more into long distance FPV with RC planes like using different frequencies for longer distance. In particular, many long distance FPV planes are using 1.2GHz for vtx (or even lower) instead of 5.8GHz.

    I've recently purchased and installed IRC 600mW 5.8GHz vtx and NexWaveRF 5.8GHz vrx module for Dominator goggles. I'm surrounded by 50-60 ft tall trees where I live, but I average about 1000m with this setup with crystal clear video (at an altitude of 80m).

    Would it be possible to install a 1.2GHz vtx on the P2, 1.2GHz vrx on the ground with 1.2GHz antennas to match for better distance? Is this a good idea or am I missing something?
     
  2. golgotha

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    I think I found the answer to my own question. Others may benefit from this information as well.

    (Taken from FPVLab.com)
    900MHz - Generally speaking this band is capable of the longest range. However it operates very near the GSM (cell phone G3) band. If there are lots of cell phone towers around, stay off this frequency. Leaving your cell phone in the car generally increases range by a factor of 3 or more. Late at night, stand up on a high structure at your intended flying sites. Look for towers of red lights. If there are none, you should be ok. If there is a sea of red lights, find another band.

    1.3GHz- Comprising of 2 channels: 1258 and 1280MHz, 1.3GHz is generally the best all around band for object penetration, range, and low noise floor. A generally safe band for mid range flight, 1.1/1.3GHz operates on the third harmonic of UHF (433MHz) making separation and good filtration critical for long range missions. This is very close to repeater tower frequency in certain areas as well. If you are around a lot of communications towers or have a cheap/old long range UHF system, it might cause shortened range. Issues with Chainlink and 1.3GHz are well known and documented. It is also know to interfere with 2.4GHz control. If using 2.4GHz control, use a filter on the 1.3 GHz system.

    2.3GHz - Just outside of the WiFi band is the 2.3GHz band comprising of 2 channels: 2305 and 2396MHz. 2.3 GHz is far enough away from 2.4GHz that it enables you to fly with other pilots who operate 2.4GHz radios but it is not recommended that you use a 2.4GHz radio with 2.3GHz video. This band also allows you to fly with other pilots on 1.3GHz without issues. Another great thing is that 2.4GHz antennas can be used with minimal reduction in range. The downside is that 2.3GHz is also used for some commercial uses such as satellite radio and thus it is not always clean everywhere. However in general this band is considered a very clean and useful band for FPV.

    2.4GHz - A very versatile band with the capability to fly multiple pilots on one band. This has a huge selection of antennas available. Unfortunately, it's a very popular radio transmitter frequency. You cannot fly this band if you use a 2.4GHz radio transmitter. This is also affected by Wifi systems. Generally Wifi is not a problem except for mobile phones used as Wifi hotspots or if you are in a heavily populated area. You also want to stay away from other pilots who use 2.4GHz for control.

    5.8GHz - Perhaps the cleanest noise floor, but the worst band for multipathing and blockage issues. Use of circular polarization is more or less necessity. However the noise floor is incredibly low everywhere. Thus this band has the shortest range capabilities, but the most consistent performance. The antennas are extremely small and so is the equipment. It works with all control systems from 35MHz to 2.4GHz. For short range around the park flying, 5.8GHz does the job.
     
  3. Meluk

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    Out of interest why do you want to fly so far?

    My basic understanding of the 1.3ghz frequency is the penetration advantage. I have 5.8 and if I fly behind a tree at 50metres away I'll get static and most likely loose all video.

    With 1.3 I am hoping for a much better outcome in the same situation. I may get a 1.3 system for my p2v+ but I am wanting better penetration than further distance. I have got 1mile with my basic 5.8ghz fatshark on my original Phantom 1. This is plenty for me. I am yet to fully test my P2V+ range.

    Sent from my iPhone using Tapatalk
     
  4. golgotha

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    I should have been more clear on why I'm interested in using another freq.

    Exactly to your point, I'm interested in penetration. I'm getting more into flying in manual mode and want to fly between trees, buildings, etc. without losing signal. When you're zigzagging between trees, 1 second of interference and losing your eyesight (video) can be catastrophic.
     
  5. Meluk

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    Exactly. There is a video on this forum I think with a 1.3ghz setup and be flies all the way down his street, through a park and into a flood drain thing. That was impressive range/penetration!

    I don't see much talk about this on this forum though. Let us know what more you find out.


    Sent from my iPhone using Tapatalk
     
  6. d4ddyo

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    What exactly is a filter? have a link to one? Any wattage max for P2?