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Wich transmitter is better

Discussion in 'Phantom 2 Vision + Discussion' started by cougar, Jun 6, 2014.

  1. cougar

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    Looking at the TX values for P2V & P2V+ it states longer rage on the P2V+ even if the transmitter has higher output on the P2V?
    I do know that the range extender on the P2V+ has better range but think that the TX from P2V would be better?
    Any thoughts?

    TRANSMITTER P2V
    ▪ Operating Frequency:5.728 GHz – 5.85 GHz
    ▪ Communication Distance(open area): CE: 300m; FCC: 500m
    ▪ Receiver Sensitivity(1%PER):-93dBm</td></tr>
    ▪ Transmitter Power:CE: 25mw; FCC: 125mw
    ▪ Working Voltage:80 mA@6V
    ▪ Battery:4 AA Batteries



    TRANSMITTER P2V+
    ▪ Operating Frequency:5.728 GHz – 5.85 GHz
    ▪ Communication Distance(open area): CE: 400m; FCC: 800m
    ▪ Receiver Sensitivity(1%PER):-93dBm</td></tr>
    ▪ Transmitter Power:CE: 25mw; FCC: 100mw
    ▪ Working Voltage:80 mA@6V
    ▪ Battery:4 AA Batteries
     
  2. Flyer91

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    I'm not sure I would worry about either one.

    From the specs it appears that they lowered the power in the Plus, but must have increased the efficiency of the antenna .... because it's spec'd as being able to transmit farther.

    As a holder of a second level FCC license I can tell you even if the antennas were the exact same, the increase of 25mw would not result in any appreciable increase in range/receiver S units.

    I suspect that if a sample of either radios were put on a test bench and ran through their paces, the differences would be more a result of their individual personalities than anything matching the printed specs.
     
  3. cougar

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    Was hoping for someone who has actually tested/used both with the stronger P2V+ range extender could chime in on the topic.
    Thank you
     
  4. Flyer91

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    My apologies ... I thought you were asking for "any thoughts".
     
  5. N017RW

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    My thought was this is no way to select either model.
     
  6. cougar

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    Have booth of them, but like to know what the real range is on the two models. Specifications say 500 meter on P2V and 800 on P2V+ but the output is higher on the P2V's TX.
     
  7. Flyer91

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    For what it might be worth ....... here is what I was trying to portray WRT the extra Tx power needed to be of any significance.

    Here’s the law every RF amplifier has to measure up to.
    Every time you double your power output, the receiver sees a 3-dB increase in strength.
    That’s only half an S unit!
    To twitch the needle a full S unit you need to quadruple your power output (a 6-dB increase)!
    For the explanation of what an S unit is (which in itself is a subjective, but accepted unit of measure) see: http://en.wikipedia.org/wiki/S_meter

    This same phenomena takes place in even non RF systems, for example ..... it is similar for your home entertainment's amplifier system.

    You don't get double the distance with double the power of an RF transmitter, nor do you get double the volume (SPL) with double the power in an audio amp system.

    However .... in an RF system you do get better range economically by first by increasing the antenna system efficiency ... which as I indicated, is what (it at least 'appears') that DJI has done ....... based upon their specs.

    But I am sorta leery of their specs them-selves being anything to hang your hat on.

    On Edit: I would also add that unless you did an actual test on a sample of these transmitters using the appropriate field strength meters and/or other test equipment, people reporting one is better over the other is purely subjective ... especially at these high frequencies where just sparse greenery, atmospheric conditions and other sources of competing RF influence between the Tx and Rx, can make a huge difference in their range.
     
  8. cougar

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    Thank you for your insight, but:
    What I really want to know is if anyone has done any actual testing of the two different transmitters.
    Speculations will unfortunately not provide an accurate answer.
    Thank you
     
  9. Flyer91

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    I 'think' RemE on the other forum did a field strength test on one of them, but I can't find the post.
    He's the same guy that posted the Yaw trim sensitivity mod the you recently referred to on that subject.
    It might be worth contacting him to see if he has that data, or would be willing to conduct the tests.
    I'd do it but all my equipment is for lower freq/higher power (HAM radio) stuff.
     
  10. RemE

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    I have both transmitters and agree that the power difference of 25mW is probably nil in real life. I haven't done any significant power or range testing with either. The PV was spec'd at the shorter distance but as folks changed antennas on the range extender it was quickly apparent that the 5.8 RC link was far greater than the rated distance. Also there was an early (and only) firmware update to the RC receiver that increased range and performance in the presence of noise.

    So my feeling is that the two transmitters are basically interchangeable with no hard evidence to back or refute the claim.
     
  11. mra1228

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    I don't think there is a difference between the control transmitters. I checked the FCC and they did not submit a new application for the V+ 5.8ghz transmitter -- they did for the V+ 2.4ghz range extender and 2.4ghz radio on the aircraft.

    The part numbers are the same (v and V+ transmitters PVT581 ) as are the FCC approval numbers (FCC ID:SS3-201309581).

    So I think in usual fashion DJI has misstated the transmit power for one or the other but unless they're messing with the FCC they are identical.

    They could have enhanced the 5.8ghz receiver on the V+ thus increasing the range. Receivers generally do not require FCC approval as they are "passive".
     
  12. cougar

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    Thank you,
    That was my conclusion as well, and the only thing different (after the software update that RemE is pointing to) is the range extender. ;)