Bringing a DIY battery powered device in flight?

[djQUAN]

Hi guys,

So, we are going on a trip to Europe (London, Germany) next month along with a large group for a tour and I wanted to bring my device on hand carry with me to keep me entertained during the flight and possibly record my trip.

The device is a simple arduino based GPS receiver that shows speed, altitude, course, and records max speed, max alt and distance. It is just a small black box approx 3" x 3" x 1" with an LCD and buttons and is fully self contained powered by a cellphone battery.

More details about my project here: http://www.quan-diy.com/projects/gps/plaything.htm

Reading about similar topics online makes me lean towards it could go unnoticed. Safest bet would be to check it in but where's the fun in that?  So I'm hoping for other opinions from here with their experience going through airport security with similar devices. (PS: no, I won't go waving it about during flight. Just keep it around for me to look at it once in a while, while it logs the distance traveled.)

[Jeroen3]

What percentage do you score on the "randomly selected" scale?
I'd say you'll be escorted to a room to demonstrate the functionality of your device at every airport.

Remember what happened to the kid that made a clock?

[djQUAN]

I'm probably in the "usually ignored" side of the scale. I'm asian but not with the really small eyes. 

When I'm not bringing anything like this device, I usually breeze through airport security without issues. (been to US, Japan, Singapore, China, Thailand to name a few)

Only times I had been stopped was in Thailand where my 8 cell powerbank got checked for capacity as the limit is 33,000mAh. The cheap powerbank (I filled it with genuine panasonic cells) was labeled as 30,000mAh so it went through fine after the inspection.

[Jeroen3]

I guess that if you power it from alkalines you'd have a chance at getting on.
But you're not allowed to bring electronics that have traces of tampering or modification. (missing screws, panels, gaps)

[djQUAN]

It is already a completed unit, powered by a cellphone cell and recharged via usb so there is little chance of it getting changed to alkaline.

Not sure about tampered electronics. First time I have heard about that. The powerbank I have mentioned has been modified though. It has a small TP4056 PCB module installed as the original charging circuitry sucks. Still passed airport security fine for my carry on.

Also thinking of bringing a few gadgets along to divert their attention from the GPS thing and make it blend in but not sure how well that would work

[Brumby]

Things get X-rayed - and if it's not something with a familiar X-ray profile, expect some attention.  That attention is going to be from people who are focused on safety - not understanding technology.

I wouldn't like to speculate on how you might go - but expect anything from a cursory glance to an interrogation.

[djQUAN]

Yeah, that was my initial concern which is why I made the second version which is arranged and wired more neatly and put in a more transparent case (in x-ray) rather than the first one which has the modules stuck all over the place in a case made from blank PCB material.

I read lots of instances with people bringing in arduino stuffs and modules without problems so I was hoping the same thing although this might be different as it is a complete device with onboard power.

[Brumby]

Yes......  a powered device does take things to another level.....

[xani]

I think it would look way less suspicious if it was powered by some li-ion battery(ies) like 18650 that were stored separately from it.

[macboy]

Even if you make it through security and onto the flight, think of the attention you will attract when you pull this thing out to "play" with during the flight.
I remember a news story about a guy a few years ago who pulled out a commercially made GPS, and propped it up to the window (for better reception). Passengers took notice, and thought he was up to something. He was promptly arrested when the flight landed. He ended up with a rather large fine, not because the device wasn't allowed, but for basically doing something that caused people to think that he was planning/attempting something. Basically disturbing the peace. I can't find the article now. Maybe my memory or my google-fu is failing.

[djQUAN]

Even if you make it through security and onto the flight, think of the attention you will attract when you pull this thing out to "play" with during the flight.
I remember a news story about a guy a few years ago who pulled out a commercially made GPS, and propped it up to the window (for better reception). Passengers took notice, and thought he was up to something. He was promptly arrested when the flight landed. He ended up with a rather large fine, not because the device wasn't allowed, but for basically doing something that caused people to think that he was planning/attempting something. Basically disturbing the peace. I can't find the article now. Maybe my memory or my google-fu is failing.

Yes, I do have concerns about that which is why I mentioned in the PS in the OP, I won't go waving it around, just leave it "running in the background". Reception is pretty good as per testing so I don't think I have to prop it up the window 

[WZOLL]

I once got a kit made Geiger counter through security and took it out on the plane to measure radiation levels at altitude. The tube and circuit was stuffed into an inconspicuous clear cassette tape case. I didn't have any problems but I wouldn't recommend it.

[buck converter]

MAKE: ran an article about those stopped by TSA (the airport security at US) when trying to bring DIY electronics on flights.

[mrpackethead]

Assuming you get it through security and onto the plane, you're going to have another challenge. GPS reception in the tin can is not going to be very good. At best you'll have a very restricted view of the sky through a window.  You might be lucky and see one sat?

You might need to talk to the airline and ask them if you can mount an antenna on the outside..    ( good luck )

[richard.cs]

When I've tried GPS on commercial flights I have struggled for usable signal on a phone (which admittedly would not have the best antenna) with it pushed hard up against the window, so security aside I don't see you getting it to work very well.

Security - wise something that looks professionally made (i.e. like you bought it somewhere) would probably not raise too many questions, but at least expect to be asked to turn it on and show what it does. But as others have said if you get the wrong person a huge overreaction is possible. 

[tooki]

I think it would look way less suspicious if it was powered by some li-ion battery(ies) like 18650 that were stored separately from it.

Absolutely not!!!! It is expressly prohibited to carry LiIon batteries that are not installed in a device!

[Beamin]

Did you hear about the guy with a nixie tube watch and shoes that didn't fit? Or did you hear about the would be suicide bomber with a detonator watch and shoes that he was going to fill with explosives who was doing a trial run? This is what the TSA does to justify its existence since it has never caught any terrorists. Why would a suicide bomber do a practice run? That's about as dumb as testing to see if a gun was loaded by pointing at your head and pulling the trigger. Yes some one has died from that too. Watch the "wonderful Whites of boone county" to see the dumbest people in America. I wouldn't bring it. I did once bring a circuit board from a TV on an airplane but I put it in clear zip lock bags and labeled everything so the TSA couldn't arrest me for terrorism. Or you could bring it and dust it with fertilizer and black powder.

[Cyberdragon]

Did you hear about the guy with a nixie tube watch and shoes that didn't fit? Or did you hear about the would be suicide bomber with a detonator watch and shoes that he was going to fill with explosives who was doing a trial run? This is what the TSA does to justify its existence since it has never caught any terrorists. Why would a suicide bomber do a practice run? That's about as dumb as testing to see if a gun was loaded by pointing at your head and pulling the trigger. Yes some one has died from that too. Watch the "wonderful Whites of boone county" to see the dumbest people in America. I wouldn't bring it. I did once bring a circuit board from a TV on an airplane but I put it in clear zip lock bags and labeled everything so the TSA couldn't arrest me for terrorism. Or you could bring it and dust it with fertilizer and black powder.

Trying to avoid getting too political, but a real good airport security should have people that know about weapons tech to know exactly what to look for and how to handle it if something dangerous is found. If they suspect something might be some sort of weapon like a bomb, they should at least know to use those explosive sniffing machines or bomb sniffing dogs. The last thing we need is some total noob being all "Oh my god, it's full of wires! I think it's deadly, we need backup" because that shows ignorance to the exact thing they should be experts in, next thing you know they might be like "Oh, what pretty red candles you have there...ok, move along." I mean that's an exaggeration, but the sad thing is this is the reality of alot of places...and to think we trust these people WITH OUR LIVES. I mean, if they don't know how to properly identify weapons, what are they going to do if they actually did find a real bomb or something?

[tooki]

You would think so... but as you know, airport security seems to largely be designed around Hollywood renditions of bombs and terrorism, not the real deal. (Like seriously, has any terrorist bomb ever made actually beeped and had large LED 7-segment countdown timers??) Yet as anyone who's ever used a real computer knows, Hollywood's interpretations of technology for the screen aren't exactly realistic. (If real computers made as many noises as Hollywood ones, and had such annoying gigantic PASSWORD INCORRECT dialogs...)

[djQUAN]

I have used in the past an android app that does some of the things that my gadget does but is somewhat inaccurate hence why I made this.

If anyone could point me in the direction to a decent app that does speed, altitude, total distance, logs max speed and location where it occurred, max altitude and where it occurred would be perfect and I won't have to bring this gadget along and won't have to worry about airport security.

[tooki]

I have used in the past an android app that does some of the things that my gadget does but is somewhat inaccurate hence why I made this.

If anyone could point me in the direction to a decent app that does speed, altitude, total distance, logs max speed and location where it occurred, max altitude and where it occurred would be perfect and I won't have to bring this gadget along and won't have to worry about airport security.

I've never been able to get a fix on an airplane with a smartphone. I'm not sure how much of that is due to being inside a big Faraday cage vs how much is due to the fact that phones use Assisted GPS, which requires a data connection to download the GPS almanac.

But from what I hear, standalone GPS receivers have trouble on aircraft, too, so it's probably the Faraday cage issue. (GPS signals are extremely weak.)

[sokoloff]

I think it would look way less suspicious if it was powered by some li-ion battery(ies) like 18650 that were stored separately from it.

Absolutely not!!!! It is expressly prohibited to carry LiIon batteries that are not installed in a device!

They are barred from checked luggage, not from cabin carry-ons.
https://www.faa.gov/about/initiatives/hazmat_safety/more_info/?hazmat=7

[djQUAN]

I was able to get a fix via mobile and it worked. The inaccuracy I mentioned was when I compared them back on the ground side by side. Speed was fine but altitude was off by a hundred feet. But when I compared my gadget vs a garmin unit, they were pretty close.

Maybe others have a better experience with a free app that they could recommend

[tooki]

I think it would look way less suspicious if it was powered by some li-ion battery(ies) like 18650 that were stored separately from it.

Absolutely not!!!! It is expressly prohibited to carry LiIon batteries that are not installed in a device!

They are barred from checked luggage, not from cabin carry-ons.
https://www.faa.gov/about/initiatives/hazmat_safety/more_info/?hazmat=7

Ack, sorry, you're right! I had a brain fart there... 

[tooki]

I was able to get a fix via mobile and it worked. The inaccuracy I mentioned was when I compared them back on the ground side by side. Speed was fine but altitude was off by a hundred feet. But when I compared my gadget vs a garmin unit, they were pretty close.

Maybe others have a better experience with a free app that they could recommend

What about a standalone, off-the-shelf GPS logger? Like the kind some photographers use for geotagging photos when their cameras have no internal GPS. They simply create a time-stamped log file in a user-selectable interval, saved to a common format like NMEA or GPX.

[djQUAN]

Don't bother. Bring it as usual and everything will be fine. If the X-ray says something, just explain to them, and the worst being the battery pack being confiscated.
I brought 12 D cell shaped ultracaps and a bunch of industrial power supplies with me when I first came to US, and airport didn't even bother letting me know, they just quietly examined my luggage and let it go.
I also once brought a rack mount server with me on a Chinese domestic flight, the airport authority called me and checked my bag in front of me, and let it go.
I also once tried to bring some explosives (trace amount, in milligrams, diluted in baking soda, used to showcase my ion mobility spectrometer in a design contest), and unfortunately got spotted by airport IMS device, and I was brought to airport police and they asked why. After knowing I'm not trying to blow up the aircraft, they confiscated my explosive samples, but allowed me to board with my equipment. That was in 2012, where China was seeing the most threat of Xinjiang/Tibet separatism terrorism, and at that time I was living in a province very close to Xinjiang. Needless to say, airport alert couldn't be more sensitive, and yet I didn't land in jail.

The battery pack is inside, soldered and screwed shut so if they won't let the cell in the whole thing stays haha. It does only use a 2000mah cellphone battery and I have brought along much bigger ones before without issue so the cell itself should not be a problem.

If all else fails either I leave it at home or bring it and see what happens. If I get stopped I just say it is a gps logger to record my trip.

[Jeroen3]

Does you GPS even work at the altitude and speed. Wasn't there some limit imposed on those?

[janekm]

I travel fairly frequently with a bag pack full of electronic prototypes and associated component and cables, and my general experience is that X-ray operators are looking for shapes/patterns that they have been trained are suspicious (“like a blade”, “like a gun”, “like explosives”) rather than things that they are not familiar with. I do occasionally have to send my bundle of wires through a second time as it’s deemed too messy to discern. My “opening tool” (blade-shaped piece of flat steel) and tweezers do get inspected on occasion, but not confiscated.
I did once cause the airport police to get called as I and a colleague were traveling with 50 D-cell Li-FeSo2 batteries with short leads manually soldered on (spares for some animal tracker experiments).
The security person politely explained that in their training they were told that the same style of battery with improvised leads was favored as a power source by makers of bombs, and they didn’t feel comfortable letting us take them on the plane, but we could pick them up from the local police station on our return.

BTW the thing you’d want to watch out for is fertilizer, if you’ve got a speck of that on your luggage it will set off the explosives testers

[tooki]

Does you GPS even work at the altitude and speed. Wasn't there some limit imposed on those?

Correct, but the limits are 1000 knots or 18000m, both far above what an airliner is capable of today. It's called the COCOM limits.

[djQUAN]

I travel fairly frequently with a bag pack full of electronic prototypes and associated component and cables, and my general experience is that X-ray operators are looking for shapes/patterns that they have been trained are suspicious (“like a blade”, “like a gun”, “like explosives”) rather than things that they are not familiar with. I do occasionally have to send my bundle of wires through a second time as it’s deemed too messy to discern. My “opening tool” (blade-shaped piece of flat steel) and tweezers do get inspected on occasion, but not confiscated.
I did once cause the airport police to get called as I and a colleague were traveling with 50 D-cell Li-FeSo2 batteries with short leads manually soldered on (spares for some animal tracker experiments).
The security person politely explained that in their training they were told that the same style of battery with improvised leads was favored as a power source by makers of bombs, and they didn’t feel comfortable letting us take them on the plane, but we could pick them up from the local police station on our return.

BTW the thing you’d want to watch out for is fertilizer, if you’ve got a speck of that on your luggage it will set off the explosives testers

Reminds me of the time when we were about to go home from Thailand. metal detector kept on beeping even when I have already taken out everything metal I had on me. Realized it was a metal strip bracket (used for the back of car stereos) I picked up somewhere and put it in my back pocket. I thought they were going to confiscate it but let me through with it when they saw it wasn't anything sharp.

[SeanB]

GPS will work in a plan4e only if you have a window seat, and place the GPS antenna right by the window to get a sky view, and have had it running ( with a decent lock) for a while before you board, so that it has a good up to date empheris of the local area before you take off, and thus can maintain lock while in flight with only the limited sky view available through the window. Will be inaccurate in height and will occasionally loce lock when no satellite is in view of the window, but will work, provided the seat you have is on the side of the plane that will mostly be facing the Equator during the flight, so the probability of having a trio or more of the GPS satellites in view all at the same time is higher.

[IanMacdonald]

One some flights you can't take a laptop unless it can be powered on.

On offshore helicopters you couldn't take anything with batteries in it, but could take loose batteries. On one occasion my colleague had to tear-down an expensive signal strength meter. and strip out  the fixed internal batteries to get it to an offshore platform.

Now, I know that terrorists are a serious concern, but sometimes I wonder if bureaucrats are an even more direct threat to civilization. 

[Jeroen3]

 , tear down equipment... Engineer + Equipment, or no engineer. You'd be amazed how quickly there is an exception for Engineer + Equipment get there to fix the problem.

[Beamin]

I was able to get a fix via mobile and it worked. The inaccuracy I mentioned was when I compared them back on the ground side by side. Speed was fine but altitude was off by a hundred feet. But when I compared my gadget vs a garmin unit, they were pretty close.

Maybe others have a better experience with a free app that they could recommend

What about a standalone, off-the-shelf GPS logger? Like the kind some photographers use for geotagging photos when their cameras have no internal GPS. They simply create a time-stamped log file in a user-selectable interval, saved to a common format like NMEA or GPX.

Back in the day I had Microsoft streets and trips and the antenna was a little square you suctioned cupped on the window of your car. It worked on an airplane. Was interesting to see the path of the plane on the map fly directly over the WTC in NYC. But that was before you could get stand alone GPS for your car and I rigged up a lap top in the front seat. It was very high tech at the time being able to get wifi anywhere near a router because passwords had to be manually configured and nobody did this at the time. I had so many internet point I put a password on gave myself and the owner exclusive access. They were none the wiser. 

[David Hess]

But from what I hear, standalone GPS receivers have trouble on aircraft, too, so it's probably the Faraday cage issue. (GPS signals are extremely weak.)

I have used my standalone GPS receivers several times on large passenger aircraft without problems.  They worked better with the external patch antenna held up against the window but maintained a lock without it using their internal helical antenna.

[djQUAN]

Update: passed through 2 airports without questions. Just stuck it in a pouch that also holds my usb cables and chargers.

One issue though, the first xray exposure seems to have damaged the eeprom as a few of the values stored in memory gets wiped out at power down, it worked before as i have been using it on the road so code is not at fault.

Interesting fact: i was seated beside the window on the rearmost seat of the plane. I was able to get up to 8 satellites locked but then everything disappeared at cruising speed and altitude. It came back when the plane slowed down nearing the destination. I suspect it is static electricity from the wind and exhaust swamping the gps signal. Let's see how it fares on the connecting flight. Waiting to board right now.

[David Hess]

One issue though, the first xray exposure seems to have damaged the eeprom as a few of the values stored in memory gets wiped out at power down, it worked before as i have been using it on the road so code is not at fault.

It would take a huge amount of x-ray exposure to damage an EEPROM beyond just erasing it.  X-rays can actually be used to erase them just like ultraviolet except you can apply x-rays through a package.  Even erasing floating gate memory takes a much larger dose than will be found in an x-ray scanner.

Interesting fact: i was seated beside the window on the rearmost seat of the plane. I was able to get up to 8 satellites locked but then everything disappeared at cruising speed and altitude. It came back when the plane slowed down nearing the destination. I suspect it is static electricity from the wind and exhaust swamping the gps signal. Let's see how it fares on the connecting flight. Waiting to board right now.

That should not happen.  What GPS was this?  I think it more likely that the software has built in limitations beyond those required for civilian GPS receivers.

[ajb]

GPS receivers that operate above 60,000 ft and 1000 nmph are controlled on the US Munitions List (because they could be used to guide missiles), so most GPS receivers will stop working above one threshold or the other*.  I'm pretty sure your commercial airliner wasn't violating either limit, but it's possible that the manufacturer was simply playing it very safe and have configured it to drop out well below the limits.  Or possibly they have higher performance and higher priced models they would prefer you buy.

* Actually the way the law is written, only devices that operate above 60000ft AND 1000nmph are controlled under the USML.  Receivers that can operate above 600m/s are classified in the US Commerce Control List, so they're still controlled, but not as severely as if they were on the USML.  Other countries probably have similar controls on GPS receivers in place, but I would be surprised if any are MORE restrictive than the US.

[Beamin]

GPS receivers that operate above 60,000 ft and 1000 nmph are controlled on the US Munitions List (because they could be used to guide missiles), so most GPS receivers will stop working above one threshold or the other*.  I'm pretty sure your commercial airliner wasn't violating either limit, but it's possible that the manufacturer was simply playing it very safe and have configured it to drop out well below the limits.  Or possibly they have higher performance and higher priced models they would prefer you buy.

* Actually the way the law is written, only devices that operate above 60000ft AND 1000nmph are controlled under the USML.  Receivers that can operate above 600m/s are classified in the US Commerce Control List, so they're still controlled, but not as severely as if they were on the USML.  Other countries probably have similar controls on GPS receivers in place, but I would be surprised if any are MORE restrictive than the US.

GPS civilian use encoding mechanism is open to the public, so if you implement the decoder with fpga then you can bypass the usml limitation.

I thought they overcame that approach by limiting how much of the time signal a civilian GPS can decrypt. Or is that just a cut off as to how many decimal places the location can read to introducing error in precision? The GPS signal is 0.00000000000001 seconds accurate but the GPS can only decode the first 0.00000000 seconds making pin pointing a location impossible. MAybe...

[Red Squirrel]

The LCD may pose a problem, because we all know real bombs have LCDs on them!     But sadly it seems that's what they're trained to look for.  Like that kid that opened up a clock and everyone freaked out thinking it was a bomb.  I personally would not chance it myself, though I tend to be randomly selected more often than not.  Probably for being a ginger, and a quiet one at that.  We can't be trusted. 

[djQUAN]

I think signal loss is due to environmental factors not software limitation as beyond about 500kph i started losing satellite locks and beyond 700kph i lost all lock, putting the device right at the window gave me a split second lock reading 930kph but lost it again. Also, while climbing to altitude, altitude readings were stuck to about 150+m. During approach, when the engine was throttled down, altitude started working right at below 500kph and 6000m. So I'm still thinking it had to do with the static or similar effect. Keep in mind I had gps lock before boarding the plane and then kept it near the window for updated ephemeris.

My connecting flight didn't fare any better. Forgot to turn it on and get a lock before boarding and being seated a seat between the window plus the a380 seems to have smaller windows too. So no data from that flight. Would have been fun as it was 12hrs Hong Kong to London.

Ps: I'm using a ublox module with ceramic antenna, typical arduino building blocks from china. I think if the eeprom has not been damaged, part of the code that retrieves the stored eeprom data may have been corrupted which explains some of them not working right.

Edit: the way the gadget was designed, when powered down, there is zero power on everything. uC does not go to sleep mode at power off. Maybe power may have been inadvertently applied while passing the xray machine. Not sure if it has any effect..

[David Hess]

You did not say which U-blox receiver you are using but:

https://www.u-blox.com/sites/default/files/products/documents/u-blox8-M8_ReceiverDescrProtSpec_%28UBX-13003221%29_Public.pdf

u-blox receivers support different dynamic platform models (see table below) to adjust the navigation engine to the expected application environment. These platform settings can be changed dynamically without performing a power cycle or reset. The settings improve the receiver's interpretation of the measurements and thus provide a more accurate position output. Setting the receiver to an unsuitable platform model for the given application environment is likely to result in a loss of receiver performance and position accuracy.

The "automotive" dynamic platform model has a limit of 6000 meters altitude and 360 kilometers per hour.

[djQUAN]

You did not say which U-blox receiver you are using but:

https://www.u-blox.com/sites/default/files/products/documents/u-blox8-M8_ReceiverDescrProtSpec_%28UBX-13003221%29_Public.pdf

u-blox receivers support different dynamic platform models (see table below) to adjust the navigation engine to the expected application environment. These platform settings can be changed dynamically without performing a power cycle or reset. The settings improve the receiver's interpretation of the measurements and thus provide a more accurate position output. Setting the receiver to an unsuitable platform model for the given application environment is likely to result in a loss of receiver performance and position accuracy.

The "automotive" dynamic platform model has a limit of 6000 meters altitude and 360 kilometers per hour.

I admit I didn't really check the limitations before, but pics of the modules are in the OP and it is using a ublox neo-6m-0-001 module. Quick look at the data sheet says 50000m and 500m/s unless I understood wrong

Edit: going to be here around UK for about 10 days, london, Edinburgh, glasgow, liverpool. Brought some pink leds and pcb modules to give to bigclive if i ever stumble upon the guy but time is limited as I'm with a big tour group and a hectic schedule. How much would shipping be? It's just a tiny box could even possibly fit an envelope. Not to mention there are a few more of our favorite youtube stars are in this area too

[David Hess]

I admit I didn't really check the limitations before, but pics of the modules are in the OP and it is using a ublox neo-6m-0-001 module. Quick look at the data sheet says 50000m and 500m/s unless I understood wrong

I knew exactly what to look for because of how you described the failure.  As far as I can tell from their documentation, the U-blox 6m supports the same modes and it can be reprogrammed; 50,000 meters and 500 meters per second only applies when in Airborn 4g mode.

CFG 0x06 Configuration Input Messages: Set Dynamic Model, Set DOP Mask, Set Baud Rate, etc.

https://www.u-blox.com/sites/default/files/products/documents/u-blox6_ReceiverDescrProtSpec_%28GPS.G6-SW-10018%29_Public.pdf

[djQUAN]

The pdf linked showed that the default was in portable mode which has limits more than enough for passenger planes. I admit I'm just a beginner so I may not fully understand what I'm saying I just used the tinygps++ library to extract the gps data from the module, I'm not sure if it has capabilities to send commands but as far as I can tell, it doesn't. I could post the code I used but I didn't bring my laptop on this trip so those interested may have to wait until I get back. I'll do more reading about the module from the info you shared thanks.

[David Hess]

The pdf linked showed that the default was in portable mode which has limits more than enough for passenger planes.

I assume it got reset at some point or maybe the library you are using configures it to a known state.

[Beamin]

The pdf linked showed that the default was in portable mode which has limits more than enough for passenger planes.

I assume it got reset at some point or maybe the library you are using configures it to a known state.

Are you making ICBM's? Why don't you install a gimbal system with autolocation that you calibrate on the ground. Make sure you use 4 gimbals so you don't get gimbal lock. Inertial guidance system. With GPS as a coarse error checking device. ICBMs are ballistic so the guidance and navigation are only needed the first 1/4 of the flight the rest can be done with physical altitude/ speed sensors and the gimbal system which can be bought of ebay and its all analog so easy to reimplement . Decoys and stage seperationcan be set off by simple timers. And the fuse could detonate off pulse radar in the tip. A really hard way to get a war head full of yard sale fliers out to a different country but you could get a large coverage area with you leaflet's . .

[A Hellene]

Ah! The civilian GPS restrictive laws, the ridiculous draconian fines on individuals that 'might have scared other passengers' by the usage of their devices on flight, any possible GPS reception jamming or spoofing procedures during flight, as well as the frenetic TSA restrictions of custom-made devices (not approved by the authorities as 'safe' --but not safe for whom, really, if I might ask?) being powered-on during (some of the) international flights, et cetera, might actually be imposed in order to prevent flat-earth theory from leaking out...

Especially after those Elon Musk's acrobatics in public...


-George

[tooki]

Tin foil hat much??

The restrictions on civilian GPS are entirely reasonable, insofar as they only kick in above 60’000 feet, which no civilian aircraft reaches. The other restrictions shown in this thread are not legal ones, but technical ones, because no one GPS receiver is optimized for all usage scenarios. Consumer GPS tends to be optimized for the typical consumer GPS applications, i.e. on the ground, at well-below-subsonic speeds.

TSA restrictions on homemade gadgets: no such restriction actually exists. But since the local TSA agents have final say on what does and doesn’t board, and they mostly got their “what a bomb looks like” training from Hollywood movies, when they see wires, they freak out. But that still does not mean it’s an official restriction.

[Mjolinor]

You have to try to educate the people at the airport. In some cases it is not possible as it is not possible to make them smile no matter how hard you try.

I had the mother of all arguments with a women at CDG who insisted I could not board a plane with my Insulin. She lost eventually due to intervention from her boss but for sure I am glad I have never had to deal with her again.

I have also carried a lot of high voltage capacitors on planes, these are about a foot long, circular and brown, oil filled paper wound things. They raise a lot of eyebrows but I have never been refused.

[A Hellene]

Please, let me apologize in advance for the long message that follows.

Tin foil hat much??

Well, not exactly that much of a tinfoil hatted; just see the smilies at my comment!

Yet, I do not buy all that governmental terrorist thing propaganda. I can remember myself boarding on planes without even having to show my ID; but this used to be happening a looong time ago, before the so-called '911 terrorist attacks' that gave birth to yet another set of uncalled wars* (while making a few very special individuals filthy rich) in expense on our freedom**.


-George



[ * ] Instances of Use of United States Armed Forces Abroad, 1798-2017, by the Congressional Research Service itself...

[ ** ] This is going to be a brief philosophical dissection of the term 'freedom,' since is not so complicated as it seems to be.

Firstly, I have an appeal to those who will feel to be inclined to, not to try to give me any nonsense about any member(s) that became ‘political,’ so their thread(s) should be pre-emptively locked or deleted. That is because, even a baby's crying to the mother for more milk is a political expression! Should it be banned, too, and be left to die from malnutrition because it ‘became political’?

Please, do not confuse Ideology with Philosophy because the opposite of superstition and ideology (which by definition are both dogmatic) is philosophy. Now, what is philosophy, in plain terms? It is, among other things, a notion according to which, nothing (and no one) is above healthy and constructive criticism. It is about questioning everything and everyone (even the so-called ‘authorities’ on any subject matter) if we really want to get to the next level of comprehending our reality.

Well, freedom is not just a notion. Freedom is one of the most important parameters for the quality of the life someone has, because being free to choose and to act is a cardinal rule for any kind of intelligent life. Even dolphins are free to choose whether to take their next breath or not, if they feel they should not (another little known fact about dolphins is that they are the only mammals, besides humans, that continue to be playing games after their puberty and until the final days of their lives).

So, being 'free' is imperative for any intelligent human being; but, be free to do what, exactly? Unfortunately, the term "freedom" does not reveal anything about the notion(s) it represents because it is just a mere translation of the Hellenic term «???» (elephteria) for a language that was created not before the Common Era and whose first writings are dated even later in time.

Our forefather Aristotle used to say that the most enslaved persons are the ones who believe that they are free (but, factually, they are not). And that has been written two and a half millennia ago; it has been written one and a half millennium before the written manifestation of the term 'freedom.'

Having the privilege to be natively speaking the mother of all the Romance languages, especially under the light of the fact that the Romance languages are derived from the Classical Hellenic language to a greater or lesser extent (since the Latin alphabet, which is now being used by the 3/5 of the Earth's population, actually is the Chalcidian alphabet, an archaic Euboean alphabet that originated from the ancient city-state of Chalcis in Euboea right after the end of the Trojan War, which has most probably taken place five thousand one hundred years ago, during 3087..3077 BCE), is very easy to explain what freedom really is because every term of the Hellenic language has a special meaning derived from its root-words, the terms it is consisted of.

According to etymology, (eleftheria: freedom) is the natural-given right (and not a legislation-given one, as we are falsely being let to believe) of every human being to be ?? (elephthein: to be going, from (elephtho: to go) ? (opou: wherever) (tis: someone) (erà: loves to, from (ero): to love/desire). It is that simple! On the other hand, 'freedom' should never be confused with 'liberty' because the latter one is the limited freedom granted to someone (for example, to a prisoner or to a solder) who is NOT free to go wherever he pleases to.

Now, are we really free? Just ask yourselves what, for example, will be the cost of a spontaneous decision for someone to not go to work this morning (or, for the whole week or month) because they felt like it: Would they not ‘lose’ their so-called ‘possessions’ that were silently placed as a collateral in order for them to be extortable and, thus, controllable by the establishment?

By definition, someone who is free is fearless. This is why all the ancient Hellenic art depicted faces having a subtle smile: the smile of fearlessness, derived from their true freedom: the freedom their free-thinking granted them. Those people were the only ones in human history that used to speak to their gods standing tall and looking them straight in the eyes and, often, arguing with them if they felt that they were wronged by their gods! Of course, I feel I should mention the obvious lack of freedom for the members of any oppressed societies due to their being under dogmatic rule, like theocracies, politocracies, or any form of membership in dogmatic clubs ruled by ways of fear...

As I have written in my signature's thread, we are born free human beings but we let ourselves to be enslaved with or without our consent and, most of the times, without our knowledge of that fact due to our cultivated ignorance. That is because freedom (or subjection or anything else) is firstly being cultivated in our minds, just like everything is. These directives are cultivated and written deep in our minds during childhood (see the paedobaptism practices that have been imposed to everyone in our society since the sixth century CE in the Middle Ages Byzantine Empire by the Codex Justinianus, which basically was a harmonization, if not a merge, of the state and the church institutions power; just see the way of creation of ruthless people or of submissive masses throughout history: Their common denominator is their deep indoctrination, which can only happen if their ‘conditioning’ begun since birth). Only after the successful completion of that procedure of cultivation of the freedom (of the subjection or of anything else), these cultivated qualities can manifest their selves in any other forms in that person’s life activity.

Do not forget that someone born in prison sees the prison bars as a decoration of the place and not as the unbendable steel restriction to their freedom, because they do not know what it is or what it feels like to be really free: they only know of what they have been told about what freedom is and feels like by their social counterparts who were also born in prison. This is also documented by Plato in his 'Allegory of the Cave' 2,400 years ago! So, what are the odds for those specific fellow men of ours to break really free from their own mental bondage, which was persistently and deeply instilled to them during upbringing? And if they managed to break free from their indoctrination, what would be the odds for them to survive in a society that has not?

[tggzzz]

Things get X-rayed - and if it's not something with a familiar X-ray profile, expect some attention.  That attention is going to be from people who are focused on safety - not understanding technology.

Most of them are mainly interested in not being fired, which means following The Book Of Procedure. How that corresponds to safety is a hotly debated question.

I was expecting aggro when taking a lightly modified reference voltage between the UK and Germany. I took a DVM plus leads to be able to show them it "worked", but in the event I just dumped it all on the conveyor belt and it sailed through, twice. A pleasant surprise, for once.

They probably realised that if they stopped me I would take great delight in a lengthy explanation and demonstration of how it worked

I wouldn't like to speculate on how you might go - but expect anything from a cursory glance to an interrogation.

Neither would I; it is also location and time dependent. That's part of the deterrent.

[David Hess]

Tin foil hat much??

Having been arrested and interrogated by local law enforcement for the crime of having a switched attenuator sitting on the dashboard of my car, nobody is paranoid enough.  I certainly was not.  Now I keep a couple of blankets in my car to throw over test equipment or any other cargo to keep it out of sight.

It was very much like a Jack Bauer interrogation scene from 24 with the law enforcement professional shaking the attenuator in my face while yelling questions except this occurred a couple years before the TV series 24 was produced.

The other restrictions shown in this thread are not legal ones, but technical ones, because no one GPS receiver is optimized for all usage scenarios. Consumer GPS tends to be optimized for the typical consumer GPS applications, i.e. on the ground, at well-below-subsonic speeds.

That behavior by U-blox receivers puzzles me.  I understand how it exists but not why the receiver cannot dynamically adapt.  None of the Garmin receivers I have used over the years has had a problem on aircraft or degraded accuracy (that I noticed) because of it.  Maybe U-blox being intended for embedded use expects the controlling system to configure the mode as needed; they are explicit that this can be done in real time.

Most of them are mainly interested in not being fired, which means following The Book Of Procedure. How that corresponds to safety is a hotly debated question.

The Book of Procedure is often (usually?) written to circumvent civil rights.  There was a dissent in a relatively recent US Supreme Court decision which pointed out that the court was laying out exactly how to do this.

[tggzzz]

Having been arrested and interrogated by local law enforcement for the crime of having a switched attenuator sitting on the dashboard of my car, nobody is paranoid enough.

Three decades ago a colleague from Colorado told me a story. He was travelling through Louisiana and was stopped by a local policeman, who asked to see his driving licence adding "now don't you go foolin' me, boy".

That puzzled my colleague until half an hour later, when he suddenly realised that the policeman was illiterate.

[Beamin]

Tin foil hat much??

Having been arrested and interrogated by local law enforcement for the crime of having a switched attenuator sitting on the dashboard of my car, nobody is paranoid enough.  I certainly was not.  Now I keep a couple of blankets in my car to throw over test equipment or any other cargo to keep it out of sight.

It was very much like a Jack Bauer interrogation scene from 24 with the law enforcement professional shaking the attenuator in my face while yelling questions except this occurred a couple years before the TV series 24 was produced.

Do tell! What did they think it was? I once had my guns taken away when the cops opened my trunk and found eight loaded ak47 magazines two ak's and a hand gun. It was a bitch to get them back and I didn't commit any crime. My pupils dilate very large at night and they thought I was on drugs and I wouldn't take a drug test (I was on prescription drugs (control IV) and they can give you a DUI even if you haven't broken any traffic laws and you are taking them as prescribed.)

[David Hess]

Do tell! What did they think it was?

What did they think the switched attenuator was?  It was incriminating, reasonable suspicion to detain and interrogate, and probable cause for arrest.  After an hour of tearing my car apart and not finding anything, they magnanimously "unarrested" me.

My pupils dilate very large at night and they thought I was on drugs ...

Or they just said that to justify reasonable suspicion.  The point of the dissent in the USSC case was that the court was laying out precise rules whereby law enforcement could game reasonable suspicion and probable cause to justify their actions to the court.

[suicidaleggroll]

I bring electronics with me all the time on planes.  Just a month or so ago I flew from Colorado to Florida with a ~2'x2' ESD bag in my carry-on that had around 20 custom PCBs inside, all populated, some wired together, some not, none in any kind of enclosure or box.  No weird looks or questions from any TSA agents on either flight (to/from).  That was probably the 10th or so trip I've made with custom electronics in my carry-on without any kind of enclosure or box, and I've never had anybody ask me about them, even flying internationally to South America and back.  I did have a screwdriver confiscated once because it was more than 6" long (WTF am I going to do with a 7" long #2 Philips screwdriver that I couldn't do with a pen?), but that's it.

The only hangup I could see here is the battery, none of my devices had any kind of battery with them.

[tggzzz]

The only hangup I could see here is the battery, none of my devices had any kind of battery with them.

For hand baggage you have to be able to demonstrate it works; dead battery => goes in hold.

The local auction house is full of kindles/phones/laptops being sold as "airport unclaimed baggage". Last month there was 193 lots, with a lot typically being 3 kindles or a couple of ipads! The month before that had 212 such lots.

[David Hess]

For hand baggage you have to be able to demonstrate it works; dead battery => goes in hold.

I do not remember them checking that on my laptop but it was back around 2005 and they did take it out of my sight so they might have checked it themselves.  I wonder now though if a laptop which boots into Linux/BSD just asking for a password for the full disk encryption as part of the boot process would be considered "working".  They did not care about my handheld GPS.

[suicidaleggroll]

For hand baggage you have to be able to demonstrate it works; dead battery => goes in hold.

I do not remember them checking that on my laptop but it was back around 2005 and they did take it out of my sight so they might have checked it themselves.  I wonder now though if a laptop which boots into Linux/BSD just asking for a password for the full disk encryption as part of the boot process would be considered "working".  They did not care about my handheld GPS.

I've flown many times across and out of the country.  I've never been asked to turn on or explain any piece of electronics, be it a laptop, phone, or bare electronics board with flying leads.  Everybody flies with at least a laptop and a phone now, if they stopped even a small fraction of them and asked them to boot it up to see if it worked, nobody would ever get through security.  They're pushing through at least a person a second at any reasonably busy airport, there's no time for that.

[tggzzz]

For hand baggage you have to be able to demonstrate it works; dead battery => goes in hold.

I do not remember them checking that on my laptop but it was back around 2005 and they did take it out of my sight so they might have checked it themselves.  I wonder now though if a laptop which boots into Linux/BSD just asking for a password for the full disk encryption as part of the boot process would be considered "working".  They did not care about my handheld GPS.

They just want to see it isn't a bomb; anything which boots isn't a bomb. Unless, of course, this week's definitions have changed. Yup, this is all subject to change, as does with monotonous regularity.

[Beamin]

I think it depends on how bored / stupid/ or how much "mall cop" syndrome the TSA agent has.

Every time I go to the airport I always notice how they don't check this and don't check that. Would be a good job to work for the TSA and see what you could slip past them. I really don't feel any safer with the TSA as most agents are people who just want a paycheck and nothing else. I don't think the TSA has caught one terrorist for the billions spent on it as the shoe bomber and underware bombers all went undetected. Next will be the asshole or vagina bomber or even surgically implanted bomb fetus pregnant bomber.

Remember that daily show interview where the guy was trying to get on the no fly list and brought all this stuff to the interview that he snuck past the TSA like a Hezbola T shirt/ bomb instructions and all kinds of other "red Flags"? But good thing cat stevens is on the no fly list the guy is a dangerously good singer song writer. He could break out his guitar in flight and start play horse in the desert with no name!!

Its really a joke PR thing and probably makes some private contractors millions.

[djQUAN]

I'm now in Germany and my device passed through Heathrow security without issues, they didn't even stop my bag full of chargers, cables and large power banks. What they did stop to check were my other tour group members bringing in snow globes, make up kits and hotel condiments

[Beamin]

I'm now in Germany and my device passed through Heathrow security without issues, they didn't even stop my bag full of chargers, cables and large power banks. What they did stop to check were my other tour group members bringing in snow globes, make up kits and hotel condiments

Snow globes? Wouldn't the snow melt in the Philippines?

[djQUAN]

They'll probably keep it in the freezer when we get back

Touring Germany at the moment, was in Berlin, now in Frankfurt then Strasbourg and Munich in a few more days. What are decent electronics stores and the equivalent of poundland here?

[janekm]

They'll probably keep it in the freezer when we get back

Touring Germany at the moment, was in Berlin, now in Frankfurt then Strasbourg and Munich in a few more days. What are decent electronics stores and the equivalent of poundland here?

The equivalent of Radioshack is Conrad: http://www.conrad.com/ce/en/

They still have a small components selection you can buy from a counter in the shop. But not really exciting compared to what you can get online...

Mediamarkt is the equivalent of Best Buy.

I don't know the Poundland equivalent, but Lidl and Aldi often carry interesting gadgets at reasonable prices.

[tooki]

They'll probably keep it in the freezer when we get back

Touring Germany at the moment, was in Berlin, now in Frankfurt then Strasbourg and Munich in a few more days. What are decent electronics stores and the equivalent of poundland here?

I don’t know anything about electronics shops in Strasbourg, but if you’re into craft cocktails, there’s a fantastic cocktail bar called Code Bar, right around the corner from the cathedral. I go there every time I’m in town. (Note to self: I’m overdue to visit Strasbourg again!)

[djQUAN]

Thanks for the info guys, will try to look for the nearest ones and check them out when we get some free time

[Beamin]

They'll probably keep it in the freezer when we get back

Touring Germany at the moment, was in Berlin, now in Frankfurt then Strasbourg and Munich in a few more days. What are decent electronics stores and the equivalent of poundland here?

Euroworld. Watch big clive much?

[djQUAN]

Euroworld. Watch big clive much?

Just a little bit sent Clive a packet while I was in the UK last week and went to poundland a few times and bought some random stuff including the famous screwdriver set

[djQUAN]

Finally back from my vacation.

On the plane trip from Munich to Heathrow, I was seated on the window just behind the wing on an A320. Reception was pretty good I could lock on up to 11 satellites and no less than 8 even with the GPS on my lap, tray or even the empty seat beside me. Plane maxed out at 851kph so the receiver is not software limited. Distance logged was 1037.1km which included the plane taxi-ing to and from the runway.

My code limited the max displayed altitude (LCD character count) to 10km but the plane went well above that so I did not have much data on that.

On the Heathrow to Hong Kong flight, plane was an A380, I was seated a little further back from the wing on the right side and lower deck. Reception was still good until we went to cruising alt and speed but I still get some locks up to 8 satellites. Stuck the GPS receiver between the blind and window with the same result. I was still able to log a max speed of 1016kph but cruising was mostly between 800-900kph. Distance logged was 11343.5km

Hongkong to Philippines flight was not so lucky. I was seated at the exact middle of the plane so no data there.

My observation still stands, the further back from the wing I get the poorer the reception is, although the exact cause is still up for debate.