Eggfinder GPS Tracker Users Manual TX Board Rev B4d RX Board Rev B4d © 2014 Eggtimer Rocketry All Rights Reserved
California Proposition 65 Warning WARNING: This product contains chemicals (lead) known to the State of California to cause cancer and birth defects or reproductive harm. This kit includes a special low-temperature ultra-fine leaded solder wire. Including the solder with the kit ensures that you will have solder that can be used to mount the surface-mount parts in the kit.
Important Regulatory Information This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation. It is intended to be used ONLY for educational and experimental use in Class II/III amateur High Power Rockets which are classified as aircraft by the Federal Aircraft Administration (CFR 14 §101.
Hope RF HM-TRP Documentation (FCC test documentation) http://www.hoperf.com/upload/rf/HM-TRP-915(20dBm)-FCC.pdf FAA Regulations for Amateur Rocketry (Part 101) http://www.ecfr.gov/cgi-bin/textidx?c=ecfr&rgn=div5&view=text&node=14:2.0.1.3.15&idno=14 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Before You Start… • If you bought a Starter Set (both Eggfinder TX and RX kits), make sure that both of them are on the same frequency (it’s marked on the package label).
An Introduction to Rocket Tracking Once upon a time it was a big deal for a model rocket to go out of sight, especially if it was a relatively large one (say, the size of an Estes Big Bertha). Rockets like that would go out of sight at maybe 1,000’, but unless your field was surrounded by trees or tall grass there was a good chance that you would get it back because it’s not going to stray more than a few hundred feet away from the launch pad. With mid-power and high-power rockets, that’s a different story.
MHz bands. These advances have made it possible to create GPS-based rocket tracking system for a fraction of what they would have cost 10 years ago. Meet the Eggfinder The Eggfinder is a GPS-based rocket tracking system that transmits using the license-free 900 MHz band. The radio modules used in the Eggfinder use the maximum legally-permissible output power for this band, 100 mW. There are actually two pieces to the Eggfinder system, the TX (transmitter) module and the RX (receiver) module.
• Follow NAR/TRA guidelines… if it’s too windy to fly, an Eggfinder isn’t going to help the situation. • Having a transmitter doesn’t mean that you don’t need to pay attention to your rocket, a visual fix on your rocket is still the best way to help get it back.
Mounting Your Eggfinder TX in a Rocket The Eggfinder TX board is about 3” long and .9” wide; with its “stick” antenna it’s about 6” long and .9” wide. It will fit into just about any rocket with a BT-50 or larger payload bay, although some of the batteries may not fit in a space that small. (9V batteries and 7.4V 2S LiPo packs are about the same size, and require a BT-55 or larger body tube.). The cardinal rule of tracking transmitter mounting is KEEP METAL AWAY FROM THE ANTENNA.
Important points to note are: • The mounting holes are sized for a 4-40 screw. Since the Eggfinder TX is relatively lightweight, you can use a self-tapping or wood screw into a plywood sled, if you do that we recommend that you put a drop of epoxy in the hole on the sled first so it won’t come loose. • You can also use double-stick foam tape, “servo tape” is the best because the adhesive is very strong and it won’t come loose accidentally.
Using Your Eggfinder TX and RX Note: If you have the Eggfinder LCD receiver, see the Eggfinder LCD User’s Guide for instructions on using it with the Eggfinder TX.
Assuming that your frequency is clear, connect your Eggfinder TX to the battery. The RED PWR LED should come on, indicating that you have power. Like the Eggfinder RX receiver, if the GREEN LED on the Hope RF module starts blinking that means that somebody else is transmitting on your frequency… figure out who it is before you start transmitting. If your frequency is clear, hold the button on the Eggfinder TX down until the GREEN RDY LED comes on (it should take about a second), then release it.
Satellite Mapping Software MapSphere GooPs (with Google Earth) The goal here is to find out where the LAST place that your Eggfinder ended up… this is going to be very close to your actual landing spot, unless for some reason your rocket drifts way out of range. Even then, you’re going to be able to get an idea of the direction that it was going before you lost radio contact, so you’re still likely to get your rocket back.
*47 the checksum data, always begins with * As an example, some “real” records taken during a flight looked like this: $GPGGA,171634,3406.6883,N,11757.4427,W,1,9,0.9,181.1,M,-33.2,M,,0000*6A This record was taken at 17:16:34 UTC (actually 9:16:34 PST), at 34°6.6883’’ N, 117°57.4427’W. There was a valid GPS fix (the “1” after the “W”), from 9 satellites.
There are a number of map sources that you can choose from, we recommend Microsoft Live Search Maps - Aerial. Having a satellite map will help in many cases, but if the location that you are flying is surrounded by roads then you may want to use the “Microsoft Live Search Maps – Streets” map instead. Sometimes the streets provide better visual clues of where your rocket went than the satellite map.
The rocket went relatively straight up, weathercocked into the wind slightly as is slowed down, drifted a little on the drogue chute, and drifted more on the main chute. Note that there is a discontinuity in the graph, that can happen once the rocket starts moving fast. Also note the small movement before launch, that’s when we were walking the rocket out to the RSO table and then to the pad… it tracks EVERY movement.
Overlaying the road map instead of the satellite map… not very interesting here because it’s about 8 miles to the nearest road. Now, this is interesting and pretty, but it doesn’t tell you exactly where your rocket landed. If you have a smartphone, you can use the coordinates to tell you where to go (more on that in a bit). If you do not have a smartphone, MapSphere does provide a relatively easy way to tell you which direction to go.
690.
In this case: Latitude = 33.828873 (North), Longitude = -113.130500 (West) This is the last position that your Eggfinder reported, and should be very close to your actual landing position. Using the Latitude/Longitude Data to Find Your Rocket Now that you have the coordinates of your rocket’s resting place, you need to able to get to it. The easiest way is to use some kind of tracking app on your GPS-enabled smartphone. We’ve used Motion-X on the Apple iPhone with good results.
http://www.eggtimerrocketry.com/page16.php?view=preview&category=9&image=135 Once you have done that, you launch, and when you get the last location of your rocket (for example, from MapSphere as detailed above), you create a new waypoint with those coordinates. Once you’ve done that, simply click on Navigate to Waypoint, and bring up either the Map or the Compass function to show you where you are in relation to your rocket and how far you need to go.
There’s pretty much no way that the rocket could be found without having a tracker. With the Eggfinder, we were able to walk right up to the landing spot without really looking around for it.
Using External Antennas with Your Eggfinder System With the included ¼ wave stick antennas, the Eggfinder system has been tested to over 8,000’ range line-of-sight with no loss of signal at apogee. This is adequate for most hobby rocketry sport flights, since it’s OK if you lose the signal as long as you pick it back up as the rocket is coming down… after all, the goal is to find out where your rocket landed, not necessarily to be able to track its flight (although it is very cool when you can do it!).
significantly more range. There are two basic types of commonly used directional antennas for rocketry applications, the panel antenna and the Yagi. A panel antenna is basically two conductive sheets of a certain size, separated by a space; the forward-facing panel is connected to the antenna signal lead, and the opposite panel (which is usually a little bit larger) is connected to ground.
antenna, you will need a “N” connector. On the Eggfinder side, you will need a RP-SMA FEMALE connector on the cable (INSIDE threads with a JACK in the center). We recommend that you use the shortest cable that you can practically use, if you mount the receiver just behind the rear of the antenna you can generally keep this cable to under 6”.
Specifications: Eggfinder TX GPS: Maestro Wireless A2235H 48 track verification channels Low power, 35 mA typical operating, 5 mA standby Transmitter Module: Hope RF HM-TRP Output Power: 20 dBm (100 mW) Center Frequency: 905.000 Mhz – 925.000 Mhz, in 2.000 MHz steps per channel Modulation: FSK Modulation Delta: 35 KHz Antenna Options: • 80 cm (1/4 wave) “Stick” permanent antenna • RP-SMA connector for external or other removable antenna Eggfinder RX Receiver Module: Hope RF HM-TRP Center Frequency: 905.
Eggfinder Quick Reference Guide Eggfinder TX (Transmitter): Battery: 300 mAh (min.), 7.
