Hammering on the Marcy 1 radio problem

The radios have plenty of range in the apartment 12ft off the ground. Put the receiver on the ground & it dies. Put the receiver on a tripod & its range slightly improves. Hold the receiver in your hand & it dies. It's as if the antennas are
getting shunted to the ground. Xbees are shielded but Marcy 1's aren't. In any case, range is far less than 72Mhz. Frequency doesn't matter.

After trying many antennas, the receiver antenna doesn't matter. It works without an antenna. The transmitter antenna is required. The best one has been a loop with no balun. Dipoles are 2nd. Monopoles with the balun suck. Unless you've got an amplifier, skip the monopole.

Loop antennas got us a big improvement but still not the same range as the 1st 2 boards.

The double sided board for telemetry goesmuch farther than the single sided board for RC so maybe double sided boards were the key.

Fuggedaboutit. That actually degraded performance. Next tried isolating the transmitter from the remote control.

That didn't do any good either. It's coming down to silicon defects.

So when you get the radios optimized, what happens but CPU overloading when all systems are running. The problem is fixed packet sizes of 100 bytes take too many clockcycles on the ground station so you really need variable packet sizes as shown in the MRF49XA reference software.

In any case, just think how radios once required huge coils & half a circuit board like your 72Mhz remote control. Never thought we'd solder chip radios on our own boards.

1 day with better radio performance got us the 1st autonomous flight out of Marcy 1. Not much of an autonomous flight but no-one ever documented an autonomous monocopter before.

You really can't get much done when working 50 hours/week & sitting in traffic another 10. No surprise Parrot Cellular whipped out WiFiquad rotors with a full time staff while you were still warming yourboss's seat.

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  • What are you using for a ground plane ? That could be part of the difference between single and double sided boards ?
  • Admin
    Jack ,
    by looks of what you have been making, surely there is not much I can say that you would not have thought of or tried already. but just incase if you haven't tried, check/try egg beater without the usual reflector which should give all round signal view ,
    here are some links I googled up ( I had made couple of them few years back for Oscar sats and was happy with results), may be this will help.
    Link 1 ( this is the one I made)
    Tried a home brewed arrow antenna too( may be for transmitter ( I don't know how you would do it but I think may be using a yagi might help)
    just my two bit...... , cheers
    My dual band eggbeater and loop ant for LEO /Oscar Sats

    The arrow antenna was made from hacked regular TV antenna plus some extra alu tubes

  • Developer
    Ehh...teams of engineers....pffft who needs them.
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