Moderator Comment by Chris Anderson on March 4, 2009 at 9:28am

Cool link, Jay. Just to be clear, this is a way to send data over audio radio channels, such as ham?

Comment by Jay Kickliter on March 4, 2009 at 10:47am

Yes, you could probably use it with just about any radio that has audio in/out jack, and a standard keying mechanism, which I think is grounding the input signal. Of course there are regulations which you have to follow, but that varies country to country. For the US, the best bet would be to get a Technician Class license. If you reading this site, you probably have the ability to pass that test with just a couple days of study, since it no longer requires morse code.

Comment by Jhon on March 4, 2009 at 12:07pm

very long means 20 km ? or 200?

Comment by Michael King on March 4, 2009 at 12:20pm

Very long is, how good you are with ham radio. I routinely communicate with the space station at well over 5000km with 25 watts.

Michael King
K1NGZ
general class HAM radio operator.

Comment by helitron on March 4, 2009 at 1:30pm

Very interesting project !

Erwin Baeck
OE6EBF

Comment by Michael King on March 4, 2009 at 1:45pm

I am all about building this little beauty on my propeller experimenters board to see how it works. i am just going to write a simple pass through app on the propeller and pass serial data from my computer using an existing aprs software app. I hope it works!

Comment by Jay Kickliter on March 4, 2009 at 4:57pm

I might try hooking it up to my scanner and capturing HEX coming in over 144.390 MHz during my drive to school. I'm in NYC, so I should pick up plenty of APRS packets. Maybe by studying the hex I could finally understand the different APRS formats.

Michael, do you know the rules if you are using your own protocol? What frequencies can you use, and do you have to have your call sign in each packet?

Comment by Kyle Sanders on March 4, 2009 at 5:23pm

Out of curiosity ... could you extend the range of a receiver (at the ground station) with a parabolic antenna, assuming it was pointed at the UAV / Tx?

Comment by Jay Kickliter on March 4, 2009 at 5:43pm

At the frequencies you'd be dealing with < 500 MHz, either a patch antenna or yagi/helical would probably be better. To put it in perspective, people using these types of transmitters in high altitude balloons transmit packets at ~300 mW which are pocked up close 300-400 miles away. Michael King would probably have a better opinion.

I have to stress, the hardware to do this has been around a few decades. Programmers have been doing it with PICs for years. But this is the first purely software microcontroller solution I've seen that can easily fit into existing projects. The Propeller has 8 processors, Phil's code takes up just one of those. You'd have to have a really stable UAV that requires very little input to control it at 1200 baud.

Comment by paul hubner on March 5, 2009 at 9:22am

Kyle,

That's exactly what I'm working on now - A ground station tracking antenna dubbed GSTaTS. I'm using it for 2.4 video today, but the concept is the same. GPS in (from the tracked object, pointing out. I'm using a Microsoft contest platform now, but plan to port to the Prop after the contest is over. I hopeto use it up to ~20 miles with my dish antenna attached rather than the Yagi, which is for my UAV. I've been involved in a few balloon launches and want to get live controllable video from the 'bird.

Re a 1200 baud UAV control - that's not too terrible for a UAV if its a reliable 1200 baud. Commanding a UAV is a lot less intensive than piloting live.

Paul

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