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Bypassing US GPS Limits For Active Guided Rockets
Kristian von Bengtson writes with a link to a short guest post at Wired with an explanation of how his amateur rocket organization Copenhagen Suborbitals
managed to obtain GPS receivers without U.S. military limits for getting accurate GPS information at altitude. Mostly, the answer is in recent relaxations of the rules themselves, but it was apparently still challenging to obtain non-limited GPS hardware. "I expect they only got the OK to create this software modification for us," von Bengston writes, "since we are clearly a peaceful organization with not sinister objectives – and also in a very limited number of units. Basically removing the limits is a matter of getting into the hardware changing the code or get the manufacturers to do it. Needless to say, diplomacy and trust is the key to unlock this."
Honestly I am a little surprised no one on Alibaba sells unlocked gps. There are enough tech manufacturers outside the US that you think someone would sell it.
In other news, amateur rocket organization Copenhagen Suborbitals recently reported theft of unspecified electronic components from its offices
Knock knock.
Whose there?
It's the government.
It's the government, who?
It's the government and we're here for our GPS units. Hand them over or be labeled a terrorist.
Look, some high up government person is going to read this, realize that some national security breach has potentially occurred, then send in the troops to reclaim those units. This won't take long.
Some people need to feel important.
And screw the 'authorization'. Switch to inertial nav once an accurate fix is acquired, and use a big enough weapon where getting close is good enough.
“He’s not deformed, he’s just drunk!”
Given that it's possible to build your own gps received from scratch anyway this seems little unnecessary. (See http://www.holmea.demon.co.uk/GPS/Main.htm for someone who did) Ok so it's not trivial but it's certainly possible.
This will undoubtedly help them time the drogue/parachute release next time. Unfortunately this failed last time in an otherwise successful guidance experiment due to the accumulated error in the intertial navigation.
This will get you on the Naughty List. Be prepared.
"When information is power, privacy is freedom" - Jah-Wren Ryel
A COTS GPS module will give you around 2 meter accuracy. One of the UBlox devices can talk to WAAS and get around 1 meter (supposedly). So my question is: why do they need any better than than?
And all this is going to do is convince the US government to turn selective availability back on and we're all screwed.
Helps to read the article. It's all about height and speed.
The actual use shown is with a balloon, so they got the altitude limit raise or removed. It's not clear about the speed limit. Also I don't know about other countries, but I asked some high power rocketry guys in the US about adding active stabilization and was informed that anything along those lines is considered a missile and would not be legal (in the US). Never mind what slashdot chose for a headline then.
"...removing the limits is a matter of getting into the hardware changing the code..."
What does this mean?
Prove anything by multiplying Huge Number times Tiny Number
Am I the only one made a little uncomfortable by this?
Headline from next year: Copenhagen Suborbitals' new franchise office in the Gaza Strip is doing amazing business...
GLONASS, anyone? Does it have the same accuracy limitations imposed?
What is the 'thingie' that looks like two diodes connected to the 0.47F cap? I can see the cap itsself is a backup power supply. I can see the resistor connected to it is to limit charging current so the inrush doesn't crash other things with the voltage dip. But what is the thingie before the resistor? The symbol looks like two diodes, one of which is shorted out to effectively remove it from circuit and the other simply positioned to keep the backup power from feeding back into the main rail - but then why use this three-pin thingie rather than a simple diode to do the job? Are SMD bipolar transistors just cheaper? Because it looks like one on the board. And if that's all it is, why not use the more recognizable bipolar transistor symbol?
http://gnss-sdr.org/node/50
You can do software GPS using $10 rtl-sdr dongles.
Who logs in to gdm? Not I, said the duck.
Geocachers everywhere just got a big chub! LOL I wonder how long it will be before super accurate handheld gps is available. Of course I'd rather have my smart be the hardware of choice. Although then somebody could hack my phone through its back door and use it for an accurate missile lock on me when I'm mowing my lawn. Damnit.
You can roll your own using off the shelf components. Though this may add a bit of weight if you use PC hardware, an FPGA, DSP, microcontroller or combination may be able to do fast real time positioning past the measly few Hz that vendor GPS modules offer.
First you need a receiver for the GPS signals:
https://www.sparkfun.com/products/10981
Then you need to process that data into a useful position:
http://gnss-sdr.org/documentation/sige-gn3s-sampler-v2-usb-front-end
Honestly, applying munitions restrictions to fast GPS does nothing to stop anyone from building a cruise missile or other GPS guided weapons. All it does is impose silly restrictions that rogue nations, governments or peoples will simply ignore and work around while denying peaceful legitimate uses by ordinary people.
THey, are, however, munitions, and subject to all sorts of restrictions on the information you can disclose. They also might have other operational restrictions imposed by the local FAA office.
But really, if you start building guided missiles, you attract a lot more attention from the regulatory authorities. Do you REALLY want to have to control all your documentation in accordance with export control rules? Make sure the garage where your missile is stored is locked?
Not the least is that putting guidance on your rocket might make it uninsurable as a "hobby rocket" through Tripoli or one of the other High Power Rocketry organizations. And, I'll bet that none of those organizations would let you fly your rocket at their meetings/launch days, just because *they* don't want to attract more regulatory scrutiny. It's been enough of a pain with the BATFE and solid rocket propellants.
So now, you'd need to go out and build or rent your own test facility, do your own negotiating with the local FCC office when doing test flights, etc. That turns a project costing a few tens of thousands of dollars into one costing hundreds of thousands or millions of dollars.
Considering most are OK with GPS-assist in their phones this is pretty much a non-issue. It affects such a small subset of people that who really cares. Model rocketry hobbyists I guess which is kind of geeky which is why I suppose it is even listed here at all. Even among that subset, there is only going to be an even fewer number that would exceed that ceiling for GPS operation.
I mean when I got into GIS the turned off the GPS limitations for civilians, THAT was a big news story. You no longer really had to cross check your positions using ground base stations at fixed coordinates for correction.
GPS assist isn't even real GPS. I always thought about those movies and tv shows where they attach a GPS device under a car to "track" it not making much sense. I mean without a direct path to satellites you aren't going to get much of a signal, and there isn't one under a car. Heck tree leaves are the biggest point in failure! I suppose you could tap into the cars antenna, but that is a bit more involved than placing a black box under the car. Then again it could be GPS-assist cell, as you don't need line of sight, just cell coverage. That could be likely easily defeated by a cell blocker, but I suppose those are illegal most places.
Random trivia questions... if I triangulate my "GPS" position by using cell tower locations, is it still called "triangulate" if I use more than 3?