Measuring distance of many targets

[coxinha]

Hi -
I am looking for a solution to measure the distance of many targets within ~300m of a given point(s)/antennas.

Of course, a simple solution would be using GPS and Data connection from a phone but I don't want to use a phone.

So, basically targets are getting close to the antenna and when they get about 300 metters the identification starts. From there, many targets can be reacheable to the antenna. As they get closer, I'd like to know which is closer versus the other.

I'm looking about measurement of 50 devices in parallel.

Please assist with a possible direction for this item and let me know if more clarification is needed on these requirements.

Thank you

 

[shrtrnd]

'Targets', kind of conjures-up a question about what you're targeting.

 

[coxinha]

'Targets', kind of conjures-up a question about what you're targeting.

My apologies - When I say targets I mean the objects I am trying to measure the distance to the antenna.
To exemplify, you can have 10 cars driving to a place. 3 of them get into the measurable range (~300m) and I would like which of these 10 is within the range. I don''t know which one will arrive first or when. That's what I am looking for...

 

[shrtrnd]

On specific trajectories or random ones. Laser range-finder?
Ultrasonic range detection?
Fixed emitter or moving? Multiple emitters or single?
Ground-clutter obstacles or line-of-sight?
The more we know, the more specific the recommendations.
Would a fixed trip-switch like a tape-switch be useful to trigger detection of approach?

 

[coxinha]

Random trajectories, laser is not an option.
Ultrasonic would be ok but I need it for city outdoors for ~300m. So not realistic.
Busy streed environment - people, cars, etc.
Re. the fixed trip-swtich - I am thinking that for closer range - but for far range I will be unable to install it for legal reasons and supportability.

 

[shrtrnd]

Pretty tough in a city environment with clutter.
Are your 'target' vehicles emitting any detectable signals of their own, or you're just trying to detect any unspecified vehicle that approaches?
Your original idea of a phone may not be too far off the mark. What else is out there that might substitute for the phone connection in your application?
GPS applications seem to be prolific these days, I'm wondering if there's something already available off-the-shelf that will do what you want.

 

[coxinha]

Pretty tough in a city environment with clutter.
Are your 'target' vehicles emitting any detectable signals of their own, or you're just trying to detect any unspecified vehicle that approaches?
Your original idea of a phone may not be too far off the mark. What else is out there that might substitute for the phone connection in your application?
GPS applications seem to be prolific these days, I'm wondering if there's something already available off-the-shelf that will do what you want.

The vehicles could be emiting a signal as part of the solution. My objective is to replace the phone because the data rates in Brazil (where I am looking to start this solution) is too high so not everybody has a data plan.

 

[davenn]

you are after a very complex radar system with built in target ID
eg .... civil or military aviation .
good luck trying to produce something like that unless you have a budget of millions and a very
bright team of design engineers and manufacturers



Dave

 

[coxinha]

you are after a very complex radar system with built in target ID
eg .... civil or military aviation with TASCAN .......
good luck trying to produce something like that unless you have a budget of millions and a very
bright team of design engineers and manufacturers
Dave

Hi Dave - Maybe I am indeed looking for something insane, but I was hoping not...

It is not exactly a radar because the cars would be communicating to the tower... if it was 1 car, maybe it would be simple, but my concern is to have multiple cars communicating with my tower and how to find out which is which and how far they are... I 'm not looking for a position, only distance...

Maybe is helps to proper explain my scenario?

 

[Martaine2005]

" Humour "...Sounds like all you need is a 'police' scanner..

It is not exactly a radar because the cars would be communicating to the tower.

but my concern is to have multiple cars communicating with my tower and how to find out which is which and how far they are... I 'm not looking for a position, only distance..

The tower (scanner) enables you to get out of there when you know they are getting close..
They usually transmit an ETA..

 

[Osmium]

It's feasible. Maybe something like this: http://www.radiometrix.com/content/uhx1
to provide communication. You'll need to find out what's legal in Brazil in terms of frequency and power. Equip each vehicle with a transceiver. Equip the tower with a transceiver.

Now you need to build a small data module to feed the transceivers in the cars and the tower. Each car would have a small GPS receiver (not a phone - just a cheap receiver). Each car is given a digital identifier ( a number). The tower broadcasts a sequence of requests equivalent to "Car 54 where are you?". If car 54 is in range, it sends back its position. The tower querys each car in its list going in a loop through all cars. When the tower receives a message from a car it will contain the car's position. From that you can work out the distance.

You need to be into programming and have knowledge of either microprocessors (like arduino) or PCs (you can use nano-pcs) and connecting the hardware. Or have someone else with the expertise.

 

[AnalogKid]

"Maybe is helps to proper explain my scenario?" Yup.

Also, why is laser ruled out. A laser rangefinder on a rotating platform is a cheap optical radar.

ak