Don Burke
Contributor
Hobbs:
I doubt that. The problems that need to be resolved for such a system would lend themselves to work on a range, not in a lab.
How about providing the name and location of the laboratory so I can check on it?
The FBI took my salvage
- Thread starter Rick Inman
- Start date
Please register or login
Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
- Ability to post and comment on topics and discussions.
- A Free photo gallery to share your dive photos with the world.
- You can make this box go away
I doubt that. The problems that need to be resolved for such a system would lend themselves to work on a range, not in a lab.
How about providing the name and location of the laboratory so I can check on it?
Groundhog246
Contributor
I think you've mis-interpreted the purpose/ability of the system (CELLDAR). It can't track people or non-metallic objects. Nor could it even identify a particular vehicle (it might be able to distigush between a large car and a small car). It work on the same principals as any other radar, that is interpreting refected RF energy. Because the high frequency range of cell phones is very close to that of conventional radar (microwave range) I can understand it's workings.
From a defense sandpoint, it means several hundred individual transmitters and separate receivers, rather that a few same point transmitter/receivers as in conventional radar, thus a lot harder to defeat or destroy. But unless they put transponders on our person or in our vehicles, it will not let them track people.
From a defense sandpoint, it means several hundred individual transmitters and separate receivers, rather that a few same point transmitter/receivers as in conventional radar, thus a lot harder to defeat or destroy. But unless they put transponders on our person or in our vehicles, it will not let them track people.
Don Burke
Contributor
Hobbs:
They aren't very proud of it. I couldn't find anything like what you've been describing on that site.
Don Burke
Contributor
Groundhog246:
Cellphones are at about 900MHz and ship RADAR is in two bands around 5400MHz and 9600MHz. That's over two octaves at a minimum.
The problems of running a 900MHz RADAR system with other transmitters on the same frequency would be pretty tough to deal with. Considering the low resolution of such a system, it wouldn't be worth the effort.
diverrick
Contributor
1) I read somewhere that some of DB Coopers money was recovered in a sand river bank, by a little girl and her family up in the PNW.
2) Jimmy Hoffa has already been found. When they removed the makeup from TammyFay Baker when she went to jail.
3) Would I turn in a briefcase full of money... Well... Let's just say
"DIVE TRIP!!!" Turn it in 1 bill at a time or fills/food/boats/beer.
2) Jimmy Hoffa has already been found. When they removed the makeup from TammyFay Baker when she went to jail.
3) Would I turn in a briefcase full of money... Well... Let's just say
"DIVE TRIP!!!" Turn it in 1 bill at a time or fills/food/boats/beer.
Groundhog246:
all I know is that atleast one contrys police force is looking at this solution for tracking ppl and cars, couse thats how I got to know about it..
I was told a scenario and deplyment plans in the scenario
wheather its the best or worst solution I dont know and honestly dont care..
will it work ? most likely. otherwise they wouldnt test it.
I can se no reason why this should not be possible.
Then again I think most things are possible to achieve. given enough time and resources...
If someone wants to know how it works I suggest you call or write the guys who are working on it.. couse I have no idea and dont claim to understand it.
I only claim that I know OF the system...
Happy Diving
Groundhog246
Contributor
Radar bands start right around the 1G range (L-Band). (More here http://copradar.com/preview/xappA/xappA.html) GSM phones also operate at 1.8GHz (1800MHz) as well as the 900MHz band.
With the low power of the transmitters and the number of cell sites I don't see it as being very practical. Certainly it would not be sensitive enough to locate a person.
Don, it's not radar in the conventional sense (emit a pulse, time the echo). More like triangulating like with a loran. Using multiple transmitters (on different frequencies as adjacent cell towers operate of different frequencies) measuring the time delay of each return, you should be able to calculate the position of the object reflecting the energy. Problems would be that cell transmitters are not pulsed, so how do you time it. And the amount of computing power to deal with every return within an area covered by only 4 or 5 cell sites, never mind a small city. Many, many $$$.
Personally, I don;t think we have a lot to worry about with this system.
With the low power of the transmitters and the number of cell sites I don't see it as being very practical. Certainly it would not be sensitive enough to locate a person.
Don, it's not radar in the conventional sense (emit a pulse, time the echo). More like triangulating like with a loran. Using multiple transmitters (on different frequencies as adjacent cell towers operate of different frequencies) measuring the time delay of each return, you should be able to calculate the position of the object reflecting the energy. Problems would be that cell transmitters are not pulsed, so how do you time it. And the amount of computing power to deal with every return within an area covered by only 4 or 5 cell sites, never mind a small city. Many, many $$$.
Personally, I don;t think we have a lot to worry about with this system.
Don Burke
Contributor
Groundhog246:
1800MHz still is more than a full octave away from the 10cm RADAR band.
My worry would be how to keep a tower several cells away from swamping your signal since it would be on the same frequency as the much weaker return off a truck.
The triangulation by range would be much the way the Chain Home system was used (since bearing resolution at 10 meters was pretty terrible). I would also expect the same problems when there were hundreds of targets to resolve.
You're right about not being like the more common pulsed system, although it would be more like Rho-Rho LORAN as opposed to the hyperbolic LORAN most people use.
The pulsing problem would not be a big deal. Look into how CWFM RADAR altimeters work. The CTFM SONARs used for under ice work transmit nearly full time. That would be the AN/BQS-14, AN/BQS-15 and (if you are a DSRV fan) AN/BQS-18. The last is a modified Ametek-Straza 500 series unit.
There is at least one deep ocean depthfinder that uses coded pulses so several pulses can be in the water column at the same time to allow good resolution at a reasonable forward speed. I saw one of those at the SONATECH plant when it was still in Santa Barbera.
I think you could use the cellular framing pulses to get a reasonable range, but the cochannel interference would require so much technology that another system would be far more cost effective. I'd use UHF television since that would get you out of the cochannel problem.
Just because some research outfit is fishing for a contract doesn't mean they think it will work. Those people have mortgages to pay too.
Anyone worried about this system would be better served doubling the aluminum foil in his hat.
Don Burke:Anyone worried about this system would be better served doubling the aluminum foil in his hat.
Darn HAT of course, aahhh I knew there was something easier than running around like a hamster in my copper meshed cage...
must be much better than the cage and bike in a upside down tub that I have..
why didnt I think of that... ahh hat...
I doubt anyone finds the system especialy worrying, but I do find it interesting.
Similar threads
