Base station details

PK-96 TNC

Connected with Keyspan USB->Serial converter. COM4, 9600 7bits, even parity, 1 stop bit.

For terminal operation, power up TNC, type a * to get it trained on the baud rate, and then type KISS ON to enable KISS mode.

UI-View32 APRS tracking software 

Requires Admin privs to run and talk to the serial port properly.

Get maps from the UI-View website. (mirrored here, unzip in the MAPS subdir of the app)

Antenna

The base station antenna is using this design, a 3-element 2 meter yagi, which should give approximately 7db of gain.

Mobile station details

Garmin GPS 35-HVS

GPS reciever with integrated antenna. Supports a wide voltage range: +6-40 volts.

Tinitrak II

Reads position data from the GPS, encodes it and transmits it on the radio.

Design thoughts

 I have some big questions about what freq to use (and if it's public aprs)

 how

 WIDE it should be... we hope to get upto about 90k with about 5watts@2

 meter.

 Thinking of using a simple j-pole.. welcome feedback and ideas.

Balloon flights are a regular occurance on APRS, happening all over

the continent. Send your information to Ralph Wallio so that others

interested in ballooning can find out about your project.

http://showcase.netins.net/web/wallio/ARHABlaunchannouncements.htm

Ralph is our official announcement bulletin board. Anyone interested

in ballooning should keep an eye on Ralph's website. Anyone interested

in sending up a balloon should announce it on Ralph's website so

others can take part in the experience.

I would suggest using 144.390, as there is a large investment in APRS

infrastructure on that frequency. Balloon payloads don't need long

paths. WIDE1-1, WIDE2-1 would be the maximum path that I would suggest

using. The packet path only helps when you are on the ground, both at

the start and at the end of the flight. When the balloon is in the

air, it has a better path than any ground based digipeater listening

for it. Longer paths only clog up the terrestrial network for no

reason, although using the above path keeps the clogging to a minimum.

Older obsolete paths were much worse when used from a balloon.

Remember, you will only see one copy of each packet via the APRS-IS

because of duplicate filtering. Rest assured that your packets will be

heard by a great many digipeaters, and also i-gated by many i-gates.

It's only the fastest digipeater/i-gate combo that gets recorded on

the APRS-IS. I'd suggest beaconing at 1 per minute. Longer means more

waiting and anxiety for you on the ground. Shorter means the

land-lubbers get cranky about all the noise. Generally if you use a

reasonable path, the general population don't squawk about rapid

beaconing from a balloon. Most people realize that the noisy package

will only be on the air for a couple hours at most.

I would also suggest backing the power down on the 2 metre

transmitter. There's no need to have 5 watts. You will be playing with

line of site propagation, and your favourable antenna position (90,000

feet) makes up for a lot of transmitter power. If you can reduce the

output power, you can get a much longer run time. You also have the

option of reducing the mass of batteries you need to send up. Reducing

the mass means more altitude. Run time is a priority, as it is nasty

if your tracker turns off before you hit the ground.

Also, is your GPS unit guaranteed to resolve a position above 60,000

ft? Many manufacturers implement the >60,000 ft AND >1,000 kts limit

improperly, and stop resolving if either limit is exceeded, rather

than when both are exceeded. Again, Ralph keeps track of the GPS units

that we have tested and proven onboard our payloads.

http://showcase.netins.net/web/wallio/GPSrcvrsvs60kft.htm

If you have any specific queries, I am more than happy to furnish what

help that I can... you can contact me directly at ve6srv(at)rac.ca.

James

VE6SRV