West Georgia Amateur Radio Society

Now that I have the electronics worked out, Blake and I will get together and mount the hardware in the payload container.  I will then take the equipment, fully charge it, and test run it overnight Thursday into Friday to verify all equipment is operating properly and that the batteries can provide power for the required four hours. We'll then charge everything back up on Friday in preparation for Saturday's planned launch.

In order to assist chase teams (all are invited to participate), there will be a cross-band repeater in the payload, operating with an uplink on 145.600^131.8 and downlink on 445.450mhz.  While we'll be using the W4FWD repeater initially, the balloon's cross-band repeater will allow us to communicate without the need for other repeaters, particularly useful if our chase moves us out of range of the W4FWD repeater. The cross-band repeater will operate on 145.600Mhz and 445.450mhz with a 131.8 tone, so a dual VFO radio (one that can monitor two frequencies at a time) is very desirable. We won't have time to help people program their radios on Saturday, so it is UP TO YOU to setup your radios, and get any needed assistance doing so, ahead of time.  You'll want to transmit on 145.600 and listen on 445.450.  Tone (131.8) on transmit is required!

Tracking the balloon or being a "Chase Team" is open to anyone (although only licensed operators will be able to utilize the repeaters).   All you need is a computer, tablet or smart-phone with internet access. The http://aprs.fi website  provides a map view (and other data) of the balloon's progress as digipeaters pickup its APRS transmissions. Here's a link that will filter down to ONLY the W4FWD-11 balloon. If you look at the site prior to launch on Saturday.  the balloon will likely appear to be parked on Old Draketown Trail, where the hardware is being tested - it might also appear to be parked in Carrollton when we test it at Blake's house inside the payload container. If you want to track the balloon directly, then you'll need APRS compatible equipment, either a radio with APRS built in, or a computer interfaced to a radio, but this is hardly a requirement. We strongly recommend teams working in groups of two or more, so the driver can focus on driving and another can function as navigator.

The balloon is expected to climb to over 100,000ft before bursting and coming back to Earth. If all goes according to plan, we should get APRS location data until near landing, telling us the general area to retrieve the payload. Finding the balloon is sort of a fox-hunt, with the APRS making it much easier to get into the general area, but still requiring some searching (and navigation) as teams make their way to be the first to find it.  Remember, while the chase is fun and competitive, we want everyone home unscathed, so drive safely and be careful out there - safety first!

For those that are curious, we'll be flying a Raspberry Pi running Direwolf APRS software, connected to a custom transmitter board utilizing a DRA818V transmitter module, powered by a 12000mah 12V li-ion power pack and a LM2596 DC-DC step down module. The cross-band repeater is a custom board that utilizes DRA818V and DRA818U modules (one is 2 meter, the other 440mhz) and a 3000mah 12v li-ion power pack and a LM2596 DC-DC step-down module. Antennas are just thin wire cut to resonance. Output on both APRS and Voice is 0.5W.

73, WX4BK
Brian