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UHF RC range extender

Posted by Chris Anderson on March 20, 2011 at 8:30pm

3689395278?profile=originalThis $200 radio replaces your RC receiver and connects to your RC transmitter. Using the UHF band and higher power than regular RC gear, it's supposed to extend your range to miles. Mostly intended for FPV flying, but has clear application for UAV use, too. 

 

The manual explains how it works:

Basically, any 4-15 channel radio can work with this system, you just need to find
the PPM signal from the radio.
We can get the PPM signal from the trainer ports for Futaba （ Non-JR ） series
radios. Because the trainer port of JR just output 4-chans PPM signal, so we need to
find the PPM o utput from other places, normally we can get the PPM signal from the
pins of the RF connector

.
You can get all the definitions of the trainer port for most of the popular radios
here.
.
For the radios which have removable RF modules, we can get the PPM signal
from the pin of the RF connector

 

Available now from BevRC.

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Comments

  • MarcS March 21, 2011 at 5:13am

    Hi Duane,

    interesting, and how do you guarantee "Sense and avoid" ??

  • Duane Brocious March 21, 2011 at 5:10am
    At the current time in the USA, there is no Line of Sight requirement for recreational sUAS.
  • MarcS March 21, 2011 at 5:00am

    Hi,

    regarding all the long range systems coming up now I´m wondering if it´s really legal to operate them under HAM license. For germany, I know for sure it´s not (I got my license some years ago and of course checked if it would be useful for FPV video and/or control). In general amateur radio is meant to get in contact with other people and/or do experiments, which both is not the case for these systems. If the laws allow you to use it, you are lucky, of course. But be aware that there can be amateur transmitters on that band running several 100W of power plus antenna gain...

    Anyway I don´t understand why you should need such a system (apart from the price :-) for doing legal UAS/FPV activities, as these have to be performed LOS! Any good 2.4GHz RC-System will give you good results in this range.

    So if you have to use a high power system you eather got interferences (which you should get rid of (better design)) or you want to fly fa away... which you "should" not do.

    So, why is this of so much interest?

     

  • Duane Brocious March 21, 2011 at 4:47am

    Yup, there is 27 Mhz FM:

    Cirrus 4 Channel Transmitter & Receiver 27 mHZ FM
  • Moderator
    Gary Mortimer March 21, 2011 at 4:46am
    Before anyone sinks too much into comms gear don't forget the WRC meeting coming up next year where the process of UAS frequency allocation continues. The bands allowed for telemetry, control and video worldwide will be defined properly soon.
  • Kevin Breen March 21, 2011 at 3:49am
    Any CB activity should be AM or SSB (single side band). CB activity has slowed a lot but you might still find some guys running (illegally, of course) a 1 Kilowatt linear amp that "splatters" all over the band if you're close enough. I'm not sure the FCC allows FM on 27 MHz because of the bandwith requirements, but I haven't looked at the regs on that. FM is used in the upper part of the 10 meter ham band from roughly 29 MHz to 30 MHz.
  • Duane Brocious March 20, 2011 at 10:39pm

    27.255 Mhz is chanel 23 on a CB also, but CBs are limited to 4 watts.

    CB on CH23 is a rare occurance nowadays (seems only CH19 and CH9 ever have activity in my area) and you will trample their signal more likely than they will yours. A 27Mhz frequency sniffer (or a couple of drives around the flight area with a CB radio on CH23) will let you know the activity.

  • Michael Zaffuto March 20, 2011 at 10:21pm
    Did some research moments ago..looks like a commercial 'walkie-talkie' states 6kHz bandwith. It uses FSK +/- 2kHz leaving the rest of the room presumably for the harmonics during 'bit' changes.  The transciever has RS232 in/out at 9600 baud, so you can get a pretty good idea of what your homemade transmitter/receiver combos performance could be, seems like a great open source project concept.
  • Duane Brocious March 20, 2011 at 10:11pm

    27Mhz requires no license. It will have to be a DIY radio as none are made anymore and those that have the 25watt ones don't seem to be selling them. An amp on a low power 27Mhz TX with a 27.255 crystal should work though. The crystals and low power radios are available in both AM and FM. Don't bother with AM.

    Seems like a cool project though.

  • Michael Zaffuto March 20, 2011 at 10:05pm

    Wow! that is awesome...btw, I think 433mhz is a great frequency band, acceptable antenna size and nice radiation charachteristics,  if I knew getting the HAM license is all it takes, I'm on board, meaning I want one and will get one, but I have to know its ok...gotta look into the 27.255 thing...need a license for it?

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