Some years ago, I started using APRS Ham Radio programs to track rockets with the 400Mhz stuff on a laptop. There was no 900Mhz back in the day. (Remember Beeline? They're still in business!) Could download photomaps of the launchsite for the laptop in advance and didn't need an internet connection. I asked an APRS program author how I could use his program to read the GPS positions for a 900Mhz GPS rocket trackers when they started coming out to the public. The APRS tracker uses an APRS word protocol when transmitting that has to be decoded. The 900Mhz stuff just uses the NMEA positions coming in.
In a matter of hours, the author told me how to use a second instance of his program to pipe the NMEA words of the rocket tracker to the first instance to display both the local position and the 900Mhz tracking rocket's position on the first instance running. If one wants their local position displayed on an APRS program, it just expects the NMEA words to come in for local GPS position and APRS packets to come in for APRS Ham band tracking of a rocket.
I might have been the only one around tracking 900Mhz GPS trackers live on a map at the time.
I will tell you, seeing the last known position of a rocket on a map really helps with recovery and with APRS tracking every position is displayed. One can see a drift trend on a live map and if no rocket at the last known position, Just whip out the 400Mhz Yagi and just proceed in the direction that is suggested by the drift trend on the map. Even without a Yagi and using a whip, if one keeps walking they'll find the rocket and reacquire the signal. A Yagi used in recovery will increase the ground footprint of the downed rocket and one might get a position sooner than with a whip. I experimented with that by using a 400Mhz Yagi for APRS recovery and when I received a signal, I detached the Yagi and put on the straight whip. The signal disappeared. Put the Yagi on and it returned. Nonetheless, if the flier is using the whip and goes in the proper direction, they'll reacquire the signal.
Found intact APRS rockets every single time once I got into the ground footprint of the tracker.
The only time one might NOT receive a final ground position is if the GPS antenna in the rocket tracker is facing the dirt 400 or 900Mhz. I never had that happen though. Always would receive when in the ground footprint of the tracker.
The reason I went with direct mapping is I saw several fliers screw up hand inputting the lat/longitude units into their handheld GPS trackers and go on wild goose chases. In one case in the APRS days, I would monitor every Beeline GPS tracker that came to fly on the laptop APRS mapping program so I could gain experience. One fellow whose flight I was monitoring on an APRS map, came back in to the flight line dejected with no rocket. I went up and showed him on the laptop map, "It should be RIGHT HERE!" He replied he put the lat/long in his handheld Garmin 60Cs mapping GPS and came up empty. I told him, "Let me see that." (the 60Cs).) He was using the wrong lat/long units! I corrected the units, input the final lat/long and he found his rocket! I had a 60Cs too and read the instruction booklet for it 6 times. Did alot of mapping APRS tracking up to that time. Knew what to look for and fixed it for him in seconds. Boy was he a happy camper when he found his rocket!
That's why I stuck with live mapping 900 Mhz GPS/APRS as it gives so much more information for recovery.
I did switch to the Android program GPS Rocket Locator:
https://download.cnet.com/gps-rocket-locator/3000-31711_4-78090096.html
as it was a lot easier to use on a smaller Android Nexus 7 for the 900Mhz GPS tracker as the ground footprint was so much smaller than lugging a
laptop around. One could download maps online of a launchsite in various resolutions and not use an expensive cell phone link. As I recall, it had a few glitches but it was still very usable. As a tip, always put the Android device in a cardboard box with a flap to guard against glare unless the Android device has a screen that can be seen in the sun. Also avoid using a phone and get an Android with a bigger screen. I didn't have one at the time that would work in the sun. Found out the hard way hence the "box trick".
I still do a bit of RDF tracking with smaller rockets. If outta sight, I hold a Garmin 60Cs or 60CsX parallel to the Yagi beam when I get a good bearing. With the "sight n' go feature" I can lock the bearing into the handheld Garmin GPS and it will guide me on the track. I try to wait until the rocket is lower especially if I can see it and lock the bearing then. If I can't see it, I wing it and if the radio signal strength meter starts to drop, I lock the bearing then. If one walks far enough, they'll find the rocket. Oh a radio with a good signal strength meter is mandatory for RDF. I saved a pile of money over the commercial RDF rocket trackers back in the day but I had to invest in a Ham ticket and radios. The radios of course had dual purpose for tracking and Ham communication.
I haven't flown in years. TRA club folded when Prefect died. My wife died from Radon induced lung cancer 6 years ago. She never smoked anything combustable in her life and we didn't know the house we bought had a Radon gas problem. She had to stay home and take care of our mentally handicapped son of whom I have guardianship of (he's 30 now). The house is abated now and Radon is hardly detectable. I retired 4 years ago as running back and forth from work to check on my son was getting to be a drag. He does fine for several hours at a time though. My two small shops, garage and basement are a mess too. Haven't had a chance to get them organized.
So I'm the chief cook, bottle washer and homemaker now. So glad my mom taught me to cook as a kid and teenager as I had to take care of myself from age 21 to 31 when I was married. Gotta go and get cleaned up and go shopping now. I have a few other things I can discourse on tracking in the future.
Kurt (KC9LDH)
NAR 11583 L2
TRA 10384 "
