Friend Compass for Festivals

Hi lately I have been thinking about trying to build a way of finding your friends when you are in a big crowd at music festivals. Everyone's phones typically die within the first day or so, so I was thinking about using two GEMMA (https://www.adafruit.com/products/1222?&main_page=product_info&products_id=1222) arduinos to communicate their position to each other. I currently have a gemma with 24 RGB LED's arranged around it. I figured if I could get the direction from the other gemma then I could light up the LED that corresponds to their direction and have the brightness correspond to their direction.

If anyone could give me some direction of the communication portion of the project that would be really helpful. I would like the communication distance to be about 200 acres or as large as possible.

Thanks in advance.

How are you going to display the information? How are you going to determine the location? Direction, distance, GPS location? How are you going to continuously notify others of the location? How are you going to power the devices? For how long? What type of terrain? Open or wooded or built up?

200 acres is a large area to be using an omni directional aerial and low power wireless.

What is the purpose of this device?

Weedpharma

You really can't beat cell phones for power saving techniques. If people would just leave them turned off much of the time, the battery charge would last for weeks.

No matter how skilled at electronic design you are, you won't be able to do better unless you enforce similar power saving rules.

there are a lot of apps for phones and solar chargers and other ways to use the cell phone.

but, to address your request. you would have to have two devices that could talk over whatever distance you have. if that is a campsite or stadium or national park. they would need to talk in some way.

then, you would need to either have both with a GPS and be able to send their coordinates, then calculate where you are and where they are....

or if you use radio direction, you would need two antennas, a wide field and a narrow field. imagine a wide field that is 180 degrees. you spin around until you get them in the wide field, the narrow field could be 30 degrees wide.it does not really matter. if you are 20 feet from someone and you are looking through a 35 degree field of view, you would find them.

you only really need one LED, just spin around until it lights, then walk. swing it right and left to define the edges of the signal.

now, you need to figure out what radio output you can use, that is battery powered, that will last longer than your cell phone.

the beauty is that it could listen, and when you press a button, send a signal, the other device could come out of sleep mode and start transmitting.

I can just see it now - a rotating antenna on the top of a "beanie cap" as you walk around to determine direction :o

gpsmikey: I can just see it now - a rotating antenna on the top of a "beanie cap" as you walk around to determine direction :o

NAW, it would get in the way of the propeller.

The OP refers to "friends" (plural) so how is he going to determine which friend is where?

Weedpharma

weedpharma: The OP refers to "friends" (plural) so how is he going to determine which friend is where

IFF squawk

I think what you want is a custom version of “Spoonr”. (Variant of “Grindr”, but we won’t go there …)

gpsmikey:
I can just see it now - a rotating antenna on the top of a “beanie cap” as you walk around to determine direction

Actually, I have been musing on a similar concept for foxhunting, but simply using two antennae as a Doppler Scan discriminator - turning the head would provide resolution of direction.

weedpharma: How are you going to display the information? How are you going to determine the location? Direction, distance, GPS location? How are you going to continuously notify others of the location? How are you going to power the devices? For how long? What type of terrain? Open or wooded or built up?

200 acres is a large area to be using an omni directional aerial and low power wireless.

What is the purpose of this device?

Weedpharma

The idea is just to tell you in which direction your friends are so you can figure out which concert they are at when there are multiple stages. Therefore, the intention was to have the have the LED's correspond to the direction they are in. The device is really just supposed to operate as a compass, distance would be nice be I believe beyond the scope of this project.

Currently what I have is this (https://dl.dropboxusercontent.com/u/24725223/20160313_152122.jpg). It is a adafruit GEMMA micro-arduino/controler. Using the NeoPixel library I can control the color and all of the 24 RGB LEDs with one control pin meaning I have two pins left on the device. It is currently powered by a 9V battery, it hasn't run out of power yet but I have been running it for about 35ish hours.

I was hoping to use some sort of radio frequency to communicate between the devices, because GPS modules tend to be someone expensive and I feel it is over the top for what I want to do. I figured the device would constantly listen and send out a pulse every 5 seconds or so to conserve battery life. As for identifying different people that's not really important but I figure that if the radio frequency system is viable I can either have an identifier in the signal or send a different frequency per person.

The device doesn't need to be excessively accurate just give you the right direction to go in. Really if you can get to the general vicinity where your friends it's easy enough to spot them.

I was wondering if potentially setting up 4 sensors in a square would allow you to figure out the direction or if the wide and narrow scan idea is better? The terrain would be open fields.