Can someone explain this system to me? I have thought about buying it. I understand you need a HAM license, but what is the difference between the 70cm and 2 meter versions? Does it work well?
Can someone explain this system to me? I have thought about buying it. I understand you need a HAM license, but what is the difference between the 70cm and 2 meter versions? Does it work well?
... and you still have to have the laptop to read the signal
Rick,
Actually no, you don't. There are two ways to do it without a laptop:
1. Use a radio with a built-in TNC to decode the APRS packets. There are two hand-held options for that, plus another one that's bigger, intended for mounting in a car:
(a) the Kenwood TH-D7 decodes the APRS and displays it on its LCD screen in lat/long format. You can manually input it into a handheld GPS or, with the proper cable, pass the NMEA GPS$ strings into a GPS directly (the Garmins do this quite nicely all the way back to my monochrome Garmin 12 up to the current full color with maps Etrex mode. It's no longer in production, so your only option is to find one that's lost on the back shelf or buy a used one, and they're seeming to go for about $150-200 in the used market.
(b) the Yaseu VX-8R also decodes the packets directly and displays them on the LCD. If you add the optional GPS antenna module to the handheld, it'll give you distance and bearing information so you can walk to it, but it doesn't apparently output the NMEA data to another GPS receiver (i.e. one with maps).
2. take a scanner or HT that doesn't have a TNC built in and output the audio into one of the little APRS decoders available. There are several made (about $100 or so) that will display the packet information on an LCD screen or, with the proper cabling, will output the data to a handheld GPS.
This is more than academic for me, by the way, since I'm sponsoring a team that's participating in the NASA Student Launch Initiative this school year, and one of the requirements is to have tracking for the rocket to assist in recovery. Right now, I'm thinking that we'll probably have a UHF B/GPS in the payload section, and a BRB transmitter in the booster section, both on separate frequencies. A portable receiving station (maybe using the Kenwood D700, the mobile radio I mentioned earlier) feeding a laptop so everyone can see where the payload is, and the chase team with handhelds (maybe the VX8R or a TH7/handheld GPS if we can swing it) for the recovery.
From what i'm reading about the system you're using, it's not that portable, or is it?
I have been in contact with Yaesu, and was told that it is possible to output the data to a GPS device. They also indicated which connector I should purchase to do so. Of course, I need to figure out how to rewire this connector for the inputs on the computer and GPS units.
Troj: Forget the yagi -- don't need it. Adrian tracked his just fine to 57k agl using just the rubber duck on his TH-D7
I'm working on a standalone TNC w/ radio receiver and LCD display, that should make for a much cheaper / non-laptop solution....just need more time
I'm working on a standalone TNC w/ radio receiver and LCD display, that should make for a much cheaper / non-laptop solution....just need more time
-- Greg
well, as usual, time is my enemy. I've got a prototype running, but the range is dismal -- measured in 100's of feet instead of miles.
Not sure you need to lug the laptop in the field -- just go to the last reported position -- surely that will be close enough unless you're on the other side of a mountain?
Speed / altitude? The BeeLine GPS has gone above 100K feet in a balloon, and well above mach in rockets. There's a question as to what happens if you exceed both of the COCOM limits (515 m/s and 18000 meters) but so far, no ones tested that for me yet
- Greg
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