Let's Make Robots!

BomBot Nomadio GC205 R/C package

Our EOD technicians have received 6 BomBots from the Air Force. These units were designed to remotely detonate roadside bombs, (EOD). Four are new and 2 are used, but none have the transmitter, only the receiver. The transmitter is a bi-directional 5-channel, spread spectrum 2.4Ghz unit made by Nomadio, model GC205. I found the 15-page owner's manual for the R/C but it is woefully lacking in technical information.

If I can find a source to purchase the transmitters and software, I can get these units working as they were intended, otherwise, all I can do is replace the controllers with a more conventional design. I have attached several pictures so you can see what they look like and a YouTube link of one in action:





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Send one to me and I would be glad to assist in hacking or creating a new controller for you :) !

looks expensive and overengineered but the coffee catapult thing was awesome

open it up and locate the receiver. I think it will be standard raw PPM receiver.

it would be a small device with 3 wires +5, gnd and PPM

something like this:


Otherwise it will be a normal hobby aircraft receiver with many outputs for many channels.

something like this:


Both are easy to hack. send us more pictures of the internals of this device so we can aid.



The Bombot transceiver is a bit larger than the typical R/C receiver. It's got a multi-wire cable that provides servo controls for the motor, steering, camera, and bomb release. The various servo connectors are using the standard 3-pin connection.

The transceiver unit also has pushbutton, used to "bind" the transceiver to a controller (it will only listen to a single controller), and a DB9 connector, which is used for software updates or wired control (the controller and Bombot can run via RS-485 instead of radio... they wanted this feature so these could be used even if jammers were operating).

I know what the receiver is and who made it, unfortunately, as of November1, 2009, they are out of the R/C business and will not supply any parts, software, or documentation. At this point, unless I can find at least 6 Nomadio GC205 transmitters at a reasonable price, I will have to replace it with a "hobby" R/C package, which I would rather not do.

I realize it would be Plug & Play and no trouble, but, this R/C package is bi-directional, 2.4GHz, spread spectrum, and has a range of 1640 feet. I can't duplicate that performance with a "hobby" R/C package. Also, keep in mind that these robots are being used in EOD applications and we don't want someone with their R/C car being able to disrupt operations and possibly getting someone killed.

I think there is an option between finding the exact transmitters you need and replacing the receiver/transmitter (R/T) pairs with plain R/C R/T pairs.

I don't know who you work for, but if you have resources and budget, can't you replace the R/Ts with something that has suitable range and security? Like this: http://www.holatronfiringsystems.com/Basic-Spread-Spectrum-Rcvr-Xmtr-Set-10000SS32.htm

I understand that the above is not necessarily a perfect fit, but there must be something out there.

1640 feet range ? thats nothing ! the hobby 2.4ghz packages have nearly a kilometer of range .

and since you will be using 2.4ghz spread spektrum, their is no way at all that someone can hop on the same channel.

The main advantage of spread spektrum is that absolutely no one can be on your frequency for more than a microsecond.


Most of the spread spectrum radios on the market use Direct Sequence Spread Spectrum (DSSS), not frequency hopping. This is the same idea as 802.11... a single token is spread among multiple carriers, so the signal looks basically like noise, rather than a narrow frequency peak.

The Nomadio stuff does both... it uses DSSS, but (at least in the later versions of the software) it also hops frequency at 100Hz. The Bombot had to contend with the video system, which is also on 2.4GHz, and fairly cheap (eg, it's crap). This was supplied by the robot builder, not Nomadio. I had to design in a very good filter, which restricts the Bombot's radio to the upper 1/3 of the 2.4GHz band, in order to get any kind of range with the camera enabled. So don't expect another 2.4GHz radio to work very well at all... even if you can set the frequency to a fixed position in the upper part of the 2.4GHz band, the camera's continual transmission will pretty much drown out the receiver's input.

I built an experimental version of the Sensor's transceiver with an LNA, which went over a kilometer in line-of-site applications, but there wasn't much interest in commericalizing this. And like most consumer radios, the Sensor was fixed at 100mW. The GC-205 can be dialed up to 250mW.

The basic reason for the existence of the GC-205 is the problem the Air Force was having with off-the-shelf R/C controllers, back in around 2004. I worked for Nomadio at the time, we were working on the "Sensor" R/C controller, which was the first all-digital, two-way R/C controller released commercially (well, aside from the 802.11 being used to control large robots). The Air Force, the Navy (NAVEOD), and Special Forces had all be trying to build a cheap EOD robot based on off-the-shelf R/C parts. At one test, one robot caught a bit of noise using the analog controller, and it glitched. You really don't want that, when the glitch could potentially release the bomb. It's was also trivial to build a more powerful controller, capable of taking the robot away from the user.

So we adapted the Sensor technology for small robots. It's basically the same thing, but no LCD, and the transceiver (what used to be called the receiver) has six servo channels (and a bunch of other I/O, but it's not used on the Bombot). And there's also a bit of fail-safe around the "throw the bomb" button.