How do tracking systems achieve such long range??

Discussion in 'Rocketry Electronics and Software' started by Clarky, Oct 9, 2019.

Help Support The Rocketry Forum by donating:

  1. Oct 9, 2019 #1

    Clarky

    Clarky

    Clarky

    Member

    Joined:
    Oct 4, 2019
    Messages:
    8
    Likes Received:
    0
    Gender:
    Male
    I was doing so researching and discovered the AIM XTRA GPS, it claims it can do up to 30km range. After staring at the tracker I saw the transmitter which was a Radiometrix TX2EH-433-64. I continued my research and discovered it for sale, however, advertises a range of 500m. So how does the tracker make this transmitter reach 30km??

    Transmitter https://rfmodules.com.au/TX2EH-433-64-5V
    AIM XTRA http://entacore.com/electronics/aimxtra
     
  2. Oct 9, 2019 #2

    cwbullet

    cwbullet

    cwbullet

    Obsessed with Rocketry Staff Member Administrator TRF Lifetime Supporter Global Mod

    Joined:
    Jan 24, 2009
    Messages:
    22,375
    Likes Received:
    1,330
    Gender:
    Male
    Location:
    Glennville, GA
    I suspect one is on the ground and the other is airborne. The answer is different depending on the question.
     
  3. Oct 9, 2019 #3

    jderimig

    jderimig

    jderimig

    Sponsor TRF Sponsor

    Joined:
    Jan 23, 2009
    Messages:
    2,865
    Likes Received:
    315
    The range is determined by a calculation of "link budget". The receiver is capable of receiving signals above a certain field strength. So the first important parameter in range is the sensitivity at the receiving end. Then you start subtracting losses that occur between the transmitter and the receivers. If the losses are less than the "budget" allowed for losses then you can receive the signal. So it is meaningless to specify the "range" of a transmitter.

    Some factors that you can use to increase the link budget over a known distance include:
    - Transmitter power
    - Receiver sensitivity
    - Frequency
    - Antenna gain (or loss)
    - Data rate of the transmission (lower is better)
    - Error correction coding of the data
     
    Steve Shannon likes this.
  4. Oct 11, 2019 #4

    Cameron Anderson

    Cameron Anderson

    Cameron Anderson

    Well-Known Member

    Joined:
    Sep 14, 2018
    Messages:
    411
    Likes Received:
    115
    Gender:
    Male
    Location:
    Reno, NV
    Keep reading...AIM XTRA claims 100 kilometer airborne range with yagi receiver.
    Featherweight claims 300 kilometers.
     
  5. Oct 14, 2019 #5

    ksaves2

    ksaves2

    ksaves2

    Lifetime Supporter TRF Lifetime Supporter

    Joined:
    Nov 25, 2009
    Messages:
    5,619
    Likes Received:
    105
    Featherweight is using a so-called “newer” Lo-Ra” technology that I believe incorporates some of the tenants that John Derimiggio mentions above. That said, I’ve been told that the beamwidth on a 900 MHz Yagi can be quite narrow to follow a rocket in mid flight with a 900 MHz tracker. Especially if the flight is mostly sight unseen. I believe the Multitronix units gets around that by using a circularly polarized antenna and more 1watt transmitter power when needed. (Correct me please if I’m incorrect as I’m being simplistic here.). The AIM Extra is on the 400Mhz Ham Band and a Yagi in that band has more beamwidth and would be easier to keep aimed at the sight unseen rocket flight. You get what you pay for.

    Never fear though because if you know roughly the direction your lower powered 900 MHz GPS tracker rocket went, slap on a 900Mhz Yagi on the receiver once the rocket is down. Since the rocket is generally stationary and if you’re paranoid like me, you’ll get a fix sooner on the thing with using a Yagi on a ground search. The rocket is generally “fixed” once down unless it’s blowing across the launch site. Not a problem in the Midwest as usually the corn stubble in a no till field will more or less fix a downed rocket in one position.

    For sport fliers who don’t expect more than 3 mile radius drift, a 100 to 250mW, 900Mhz GPS tracker should be more than adequate to find your rocket.
    Except................ Out west on the playa that sucks up Rf once the rocket is on the ground due to the dissolved salts in the so-called soil. If a rocket drifts really far and the final fix is not close to the final touchdown point, it might be a challenge to find. For “flat-landers” more of a piece-o’-cake. Kurt
     

Share This Page