APRS Packet Radio

Sniper King

Is Packet radio doable with the propeller?· if it is then a really small unit could be built.

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·- Ouch, thats not suppose to be hot!··


Michael King
Application Engineer
R&D
Digital Technology Group

Post Edited (Sniper King) : 8/28/2008 9:34:46 PM GMT

Timothy D. Swieter

I was wondering something similar. I haven't really researched this, but just a thought. Use an off the self transmitter with a a mic input. The Propeller could generate the tones needed and send them to the transmitter. The Propeller would be attached to GPS and other sensors and generate the packet of data to be sent.

Again, my guess would be yes and I am curious what steps to take. Someday I would like to do a high altitude balloon so I briefly looked at what others were using.

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Timothy D. Swieter, E.I.

www.brilldea.com·- Prop Blade, LED Painter, RGB LEDs, uOLED-IOC, eProto fo SunSPOT, BitScope
www.sxmicro.com - a blog·exploring the SX micro
www.tdswieter.com

Sniper King

i found this!· i think this could be adapted quickly!



http://users.rcn.com/carlott/avr/avr_mx614_schematic.PDF

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·- Ouch, thats not suppose to be hot!··


Michael King
Application Engineer
R&D
Digital Technology Group

TreeLab

Check out the TinyTracker3+ at http://www.byonics.com/tinytrak It is a nice PIC system, but will only encode the GPS data, and not arbitrary APRS packets.

I tried to code a general APRS device on the Prop using a modem chip and some info from the Tucson, but the unusual encoding and CRC's killed my enthusiasm fairly quickly.

Check out the Tucson Radio site, it has a wealth of APRS info, including their AX.25 encoder board. It uses the same modem chip that I looked at, but the code versions that are floating around are a bit out of date. If you are familair with PIC programming (I am not), you can probably start with their code and port it to the Prop.
http://www.tapr.org/aprs.html

Cheers!

Sniper King

I totally saw that one and i might be a way to go. The one i found, the prop would easily be adapted. Then we collectively can write some cool code to do multiple things including unattended weather stations, GPS tracking, AUTONOMOUS SAILBOAT... Maybe!

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·- Ouch, thats not suppose to be hot!··


Michael King
Application Engineer
R&D
Digital Technology Group

Sniper King

I created this schematic but since I have never touched this chip before i may be stupid here.· this is a modified schematic from the above posted schematic of a Packet radio board.

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·- Ouch, thats not suppose to be hot!··


Michael King
Application Engineer
R&D
Digital Technology Group

Timmoore

I would expect you can remove the mx-614 completely. If I remember correctly its a 1200 baud FSK modem. The prop should be able to generate the correct frequencies for send and check for the 2 frequencies for receive - probably with 1 cog - use 1 counter for frequency generation and the other counter for detecting incoming frequency. In fact integrate the counter control into the fullduplexserial so you serialize the data but rather than output the bits, control the frequency generation counter to output 1 of 2 frequencies, similar for receive whenever you want to read a bit, read the detection counter to work out the current incoming frequency.

Sniper King

That is way out of my programming range for the Prop. I really want to do this. This would make packet radio an inline addon to an HT. This would make paket radio way more usefull due to the fact that those stupid little boxes go for $100-$200. Imagine an 25 dollar Packet system. On top of this it would fit in a fiml canister or something more professional but similar in size. Then add the fact that you could put a USB chip onboard for direct computer operation and have a simple TTL in/out.

This thing would be easy to make and very cheap. Packet radio would be flooded with them and there would be a huge growth in packet radio.

Of course my need is selfish.· I want the ASB (Autonomous SailBoat) to be exclusively run by the Propeller.· Communication,guidance, everything!

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·- Ouch, thats not suppose to be hot!··


Michael King
Application Engineer
R&D
Digital Technology Group

Post Edited (Sniper King) : 8/29/2008 9:32:03 PM GMT

Timmoore

I am going to take a look over the weekend, I think its straightforward to mod fullduplexserial. I can't test it for real, I didn't re-take my license when I moved from the UK but I can test it in loopback.

Jay Kickliter

I've been hoping for AX.25 also. It would save me a lot of money and a little bit in my balloon project if I could just output the tones directly from the Prop. My main motivation to learn assembly (which I just started) was to do this, but I wouldn't be disappointed if someone beat me to it.

The thing I don't like about the miniature trackers is that they either send APRS packets or one way messages, but can't seem to do both. What would be perfect is an object that you could just Start, and had a method such as SendAPRS(@lat, @long, @speed, etc.), or SendUNPROTO(@station, @message).

Tim, one thing I noticed about the AX.25 protocol is that the bits of the station field are all shifted for some reason.

Timmoore

I was just going to look at the problem of using the prop as a replacement for the mx-614 modem. Implementing the ax.25 prototocol is another problme that would need to be solved.

Ken Gracey

I'm in the process of setting up a two-way modem using 5W HT radios (Yaesu VX-6s). Each radio is going to be connected to a Tigertronics RTX-12OEM modem. This is a great way to go, because you get the high power RF link and serial I/O at 1200 bps.

Ken Gracey
KI6HBT

Sniper King

I am glad other people have interest in this as well.· I agree with Jay on this.· An object that could output APRS Packets with a simple method call would be so cool.· Currently most of the little modems are designed to be plugged into a gps.· this really wastes the power of the modem itself.· I want to build long range APRS weather stations.· Also I enjoy packet communication with the ISS.· My autonomous sailboat project will rely exclusively on APRS for position telemetry and mission updates.· Smaller is gooder!· I wish timmore lotds of luck this weekend!



I am reading the APRS manual to see how to produce acceptable ax.25 frames.· It uses a lot of big words though :-).

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·- Ouch, thats not suppose to be hot!··


Michael King
Application Engineer
R&D
Digital Technology Group

Earl Foster

I have been using the OpenTracker (http://www.argentdata.com/products/otplus.html) for my APRS tracking system on my high altitude balloons.· It is only a one-way device but it runs open source code written in "C" so you might find it useful.·
The radio I currently use on only 0.384 watts output but I can pick up the signal for miles, especially when airborn.· For a radio you might want to look at incorporating the MX146 (http://www.argentdata.com/products/radios.html).· It is a SMT 2-meter transmitter designed for short burst of data (5:1 ratio).· It is completely programmable and has the standard preset APRS frequencies used around the world.·
Eventually, I would like to incorporate 2-way·APRS messaging using the Prop but my·SPIN knowledge is still·on the low end right now.· I know I would use the object if it was available.




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WWW.HAPB.NET

"Don't ask yourself what the world needs - ask yourself what makes you come alive, and then go do it." - H.T.Whitman

Jay Kickliter

I've been looking at these Radiometrix modules. They have the modem and transmitter built in. Its what Byonics uses in the Micro-Trak APRS transmitter. The problems is that they come standard in European frequencies, and I don't know what kind of a volume of order is required to get one with the standard American freq.