Eggtimer Rocketry
 
Eggfinder

Eggfinder GPS Tracking System


The Eggfinder is a GPS telemetry system that sends out a stream of NMEA-formatted serial data from a transmitter located in your rocket to a receiver on the ground that you connect to a laptop.  The purpose is to track your rocket in flight, and more importantly get it back.  Using one of the latest integrated GPS modules, the Eggfinder is a mere .9" x 3" and weighs under 20 grams.  It sends out a position update once a second, giving you the exact latitude and longitude of the rocket at that point in time.  This data can be fed real-time into a number of free software programs to track your rocket, and if using something like Google Earth or MapSphere you can actually get a map that will show you where your rocket landed.  If you have a GPS-enabled smartphone like an iPhone or Android, you can plug the landing coordinates into an application such as MotionX and you can literally walk right up to your rocket.

Like other Eggtimer Rocketry products, the Eggfinder is sold as a kit, the complete system is under $100.   This makes an Eggfinder the least expensive GPS tracking system on the market, by a wide margin.  We use RF radio modules that transmit on the 900 MHz license-free ISM band at 100 mW, and have attained a clear-air range of over 10,000' with no signal loss (the rocket went out of sight but starting coming down before we ran out of signal!)   If you change out the included 1/4 wave "stick" antenna on the receiver for a RP-SMA connector and a directional panel antenna (under $20), you can easily double this range.  This makes the Eggfinder an ideal tracking solution for those situations in which your rocket may not be strato-busting but may go out of sight and therefore be difficult to find.

The system actually consists of two kits, an Eggfinder transmitter module and an Eggfinder RX receiver module.   Most of the parts are standard through-hole parts, except for the GPS and radio modules, and one 8-pin SOIC microcontroller on the TX board.  Even though the GPS module and the RF transceiver modules are surface mount modules, they are not terribly difficult to solder onto the board; we include special .020" low-temperature no-clean solder to make it easier.   If you have any prior kit-building experience (i.e. you've build an Eggtimer Flight Computer) then  putting an Eggfinder together will be a breeze.

Specifications

Eggfinder TX Transmitter Module

Maestro Wireless GPS module accurate to 2.5m, using SIRFstarIV.

Battery: 2S 7.4V LiPo battery at minimum 250 mAH recommended

Simple to operate:  Just plug in the battery connector, and it's on.

1-Second "heartbeat" LED to let you know that it's picking up GPS satellite data.

Current draw: Operating, about 70-100 mA.  Standby:  about 10-20 mA.

Size:  .
Eggfinder TX: 0.9"w x 3"l  x .4" h ( included 1/4 wave antenna adds about another 3" in length), fits into a 24mm (BT-50) tube.


Weight: About 20 grams.



Eggfinder RX Receiver Module


Easy to operate:  Just plug the USB cable into your computer, and it's on!

Simple serial-NMEA data connection (9600 baud, 8 bits, no parity), works with any GPS-enabled application, or you can use a serial terminal program to simply capture the NMEA data stream for later use.

Can be used with an external serial-Bluetooth(R) module and battery (not included) to create a handheld wireless receiver solution for use with your Android/Windows smartphone or tablet.

Size:  .9"w x 2.25" l x .3"h (+ about 3" for the 1/4 wave antenna), + 3' USB data cable