PopSci-Core Entry for Security Comp

Postby ykh » December 7th, 2004, 5:54 pm


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this projects not doing anything on my harddrive. updated the satellite and transmission dish. nicer now. couple other minor details. otherwise that's it.

four day project. no real sketching. one fast thumbnail. one foamcore mock-up. rest of it in CAD. i'd post the write up but it sucked bad.

Image

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Image

Postby skinny » December 7th, 2004, 8:06 pm


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Very interesting. I've also been starting to think about new products geared towards todays era of "heightened awareness" and other things people don't generally want to think about. I tend to start exaggerating them though, turning them into comical concepts. I could share one, but probably too tasteless.
Is all of the tech in this concept current/actual or is some of it blue sky?

Postby ykh » December 7th, 2004, 9:30 pm


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pretty feasible. originally just a dosimeter dogtag. half day researching saw some stuff out now thats pretty small. including geiger counter watches. and watches for kids that call 911 if they're missing. stuff like that. all pretty small. i just put the pieces together (during an email explaining what i was working on - thats when the whole "loop" idea hit).

it really needed a good write up. half the idea is in the business plan. good exercise tho. maybe i'll get back to an early concept i couldnt resolve. much more fun. and weird.

Postby ykh » February 22nd, 2005, 1:56 pm


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cleaning up and found sketches. been sitting on scanner for weeks. not much but here it is.

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Last edited by ykh on March 13th, 2005, 3:46 pm, edited 1 time in total.

Postby me » February 22nd, 2005, 5:46 pm

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Interesting idea. The whole dog-tag thing works well too. I could see the final product having the same pressed alloy aesthetic as the real thing, maybe with some nice machined surfaces for contrast.

The only problem (for a real world perspective that is) is the GPS patch is shielded by the LCD, plus the patch needs to be angled towards the sky in order to 'see' the satellites. This is especially important in a built-up environment (where the fear of an attack would probably be the greatest) because the building tend to restrict the line of sight to the sky to a small arc overhead. :wink:

Postby ykh » February 22nd, 2005, 6:24 pm


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"The only problem (for a real world perspective that is) is the GPS patch is shielded by the LCD, plus the patch needs to be angled towards the sky in order to 'see' the satellites. This is especially important in a built-up environment (where the fear of an attack would probably be the greatest) because the building tend to restrict the line of sight to the sky to a small arc overhead."

OLED, not LCD. not only GPS, but GPS/Wireless. not "patch", plastic cover for detector (but GPS also underneath).

but curious about

1) "shielded" issue
2) "angle to see sky" issue
3) "line of sight.... small arc" thing

explain?

Postby me » February 23rd, 2005, 5:29 pm

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Sorry if that came across as overly critical ykh, it was not meant to be.

"Patch" is the oh-so-technical term for the small (20mmx20mmx2-4mm) ceramic GPS antenna. Generally, it needs to be mounted with clear PCB space around it (ground plane) to improve reception. They tend to be directional (they have gain-lobes or something) so will receive signals best from perpendicular to the mounting surface. Because the GPS signal is so weak (much weaker than the cellphone or wireless net signals) if you cover them with anything more than air and thin plastic (2-3mm) they don’t work very well at all. Anything metallic over the path will shield the signal; this includes anything like LED, LCD or OLED displays.

When I talk about the small arc or line of sight, I'm talking about the line of sight from the GPS receiver to the satellite overhead. If anything solid gets in the way (building, big trees etc) the signal is lost. A GPS receiver needs to "see" three satellites minimum to work. If you are surrounded by lots of tall buildings, there is only a small area of sky in which to see the satellites, and since there are a limited number of them up there, the chances of being able to see three or more is reduced.

The other option is to use a more conventional non-directional antenna (old cellphone style), but this would ruin the dog-tag idea.

Phew. I've been hangin around the engineers too long :roll:

Postby ykh » February 23rd, 2005, 6:06 pm


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"Sorry if that came across as overly critical ykh, it was not meant to be."

not at all. only a 4-day effort.

"if you cover them with anything more than air and thin plastic (2-3mm) they don’t work very well at all. Anything metallic over the path will shield the signal; this includes anything like LED, LCD or OLED displays."

Patch is new term for me tbh. but if you read closely, i accomodate -

"RadTag sends via wireless and receives GPS/wireless."

i didnt depend on this device receiving GPS signals. but based on some new child-tracking tech, figured wireless could accomodate high density areas. for rural areas, radiological contamination is less likely (poor terrorist target) and GPS signal reception would be clearer. [edit>]big issue in remote areas is sending an alert. receiving one is also issue, but there are options for resolving that (e.g. emergency broadcasts from private satellites - like XMRadio. etc). thinking rural folks get shortchanged if they're attacked though.[/]

"the line of sight from the GPS receiver to the satellite overhead. If anything solid gets in the way (building, big trees etc) the signal is lost. A GPS receiver needs to "see" three satellites minimum to work. If you are surrounded by lots of tall buildings, there is only a small area of sky in which to see the satellites, and since there are a limited number of them up there, the chances of being able to see three or more is reduced."

iirc GPS satellites send out an low-power, omni-direction radio pulse. there is no "sight" similar to microwave reception (hi-freq/high-power = directional). and GPS uses intersection of three satellite distance "spheres" to triangulate position. Earth is the fourth sphere to reduce errors. i believe the issue w buildings is ghosting. radio wave reflections induce errors similar to what you get on a tv screen. but there is always 3 satellites above.... somewhere. that's how its designed.

feel free to correct me if i'm wrong. been awhile since i'd worked w GPS stuff.
Last edited by ykh on February 23rd, 2005, 7:31 pm, edited 1 time in total.


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