APRS tracking (hey rebelk5frk!)

[got_mud]

i dived into the radio active networks page to learn more about aprs and am now mentally numb. can you give me the basic rundown on the whole deal?

i would have sent a pm, but i think this stuff is cool and everyone should hear about it.

thanks

 

[rebelk5frk]

Well I just sent a PM yesterday to someone about the same subject so I guess others will find interest too. /forums/images/graemlins/wink.gif

APRS is both simple and complex at the same time if that makes any sense... A very basic use is vehicle tracking. The bare minimum for normal APRS tracking is a radio, a GPS, and an encoder of some sort such as a TNC, Laptop, "TinyTrack" etc. Or if you just want to have a stationary APRS station then all you need is a radio and some sort of encoder with your position programmed in.

APRS is used quite a bit for search and rescue operations and special events such as road races etc.

The idea is you have a gps spitting out NMEA formatted sentences via a serial port that shows your position, speed, altitude, etc. The encoder (several options are available) takes the data from the GPS and turns it into formatted AX.25 packets (a standard ham radio data format) and feeds the data to the radio at 1200 baud as "Audio Frequency Shift Keying".
That just gets your signal out there for the world to hear. Then you can use a similar setup with a radio and a TNC attached to a computer or pda etc running specific software to plot the information on a map.

APRS also has provisions for short messages and weather reports among other things. Most active areas also forward the information heard on the APRS radio frequency to the internet so you can track things over very wide areas of the world/country.

There are also a few satellites that forward APRS packets over large areas.

APRS isn't just limited to regular "ham radio". The information can be transmitted over just about any medium. Professional tracking systems use a similar system using cellphones. Some people even use it for tracking model rockets, airplanes, weather balloons, and the list goes on and on.


My setup I have in my vehicles is a GPS receiver connected to a Byonics "TinyTrack3" into a 2meter ham radio. I also have a radio tuned to the national APRS frequency (144.39mhz) at home connected to the sound card of my computer. Special software decodes the information and makes it available to the APRS software I'm running which has several maps loaded to show the position of my vehicles at all times. The software I run also forwards all data heard over the radio to the internet so I can be anywere in the world and see where my truck is parked. (a poor mans Lojack /forums/images/graemlins/grin.gif )

Click here to see a few examples of what the information looks like on the internet.

oh and before I forget (APRS is a registered TM of Bob Bruninga )

 

[got_mud]

** drools on self in a tech junkie kind of way **

so, where do i get the software? and how would i go about making a mobile unit capable of txing its 20 to a base unit and still rx and display the 20 on my laptop of other mobiles in the field? can this be done with software? i don't like the idea of having to use three radios in my mobile just to tx and rx this data and still be able to communicate with other units, assuming that i have the concept correct. most of the other units in my group are cb'ers and frs'ers and are leary of investing the additional $$$ it will take to get this going. i am getting closer and closer to getting my rescue operation off the ground, though. /forums/images/graemlins/laugh.gif

/forums/images/graemlins/thinking.gif let me verify the concept- to tx its 20 each rig must have a dedicated radio with a 1200b data capability, a gps with nmea format data export capabilty and an encoder (tt3, tnc, etc). to rx the 20 of units a station must have a dedicated radio, a pc with sound card and the appropriate software to decode the data. is that the basics?

what would be the most basic gps that would work for this application? i thought of using deluo units in each rig but the cost is near that of an operational gps with display. for a few dollars more a self standing gps can be bought and be usable for more than just unit tracking.

any other thoughts on this stuff?

would you like to make an equipment donation to my non profit organization? please?

and also- thanks for the 411.

 

[got_mud]

oooooooooooooooo more thoughts...
couldn't i use a scanner to rx the signal of mobile units? ie using the sound card method.

 

[rebelk5frk]

Well hmmm where to start.... if you just want to RX then yeah a scanner would be just fine. For RX and TX it doesn't require 2 seperate radios, 1 radio can do both. For RX and TX it requires a TNC or similar setup. The TinyTrack can only TX. Also if you are using APRS on a semi private frequency ie: not the main APRS freq. then you can also wire it all up so you can also talk on the same freq. The TT3 has the ability to TX only after you release the PTT, sort of like a roger beep you hear on CB.

If you plan to have a laptop in your truck then you could just use the sound card for both rx AND tx and save buying one more thing. Using a soundcard takes a bit of processing power so you'd want to use a somewhat newer laptop... 300mhz or faster.

APRS will also work with FRS radios as long as you have a microphone/spk jack on the radio. The main problem is you would be limited on range severely. (although there is a workaround for that if you went that route) CB's would work also in theory but IIRC packet is not legal on CB. It wouldn't work very well anyway with all the noise.

As far as software goes, there are plenty of choices. There is software for PALM OS, WinCE, MAC, Win, Unix/Linux, etc. My favorite is a program called Xastir available at xastir.org but is not for the faint at heart to install since it is designed for Linux but also works under Windows with some work. The two main programs for Windows is Winaprs and UIview. a quick google search will find the links for them.

A program called "AGW Packet Engine" is what is needed for using a sound card as a modem for APRS or other packet programs. AGWPE can be found here

oh and for a GPS anything that spits out standard NMEA data will work just fine. I use the Deluo in my car and have all of the tracking equipment tucked out of site so the mouse style receiver was all I wanted in that case. In my K5 I have a Garmin GPS 12XL that I picked up for a little less that $100 from ebay so I can pull it out of the vehicle and use it for other things if needed. So it really depends on what other possible uses you might have for the gps when you pick which one to get. If it is always going to be connected to a laptop then even a mouse style gps is plenty since you can use the laptop for display purposes.

 

[got_mud]

** still drooling **

so... my thought for the main mobile unit was to use a gps mouse to input data to the laptop via usb, as i do not have a serial port on my compaq. from the laptop i would have to export data to an encoder to connect to the radio, and without a serial port, how should i go about that? this assumes that computer is capable of receiving the data and exporting it simultaneously. i will take a look at the software you listed and see what i can learn from it.

 

[rebelk5frk]

Sounds like you got a plan going. The USB GPS might work but most APRS software expects a serial device for the GPS. You would have to check the documentation or the manufacturer...It might emulate a serial port. You would also need a USB to Serial adapter for just about any encoder options... The adapters are pretty cheap and can be found with multiple serial ports and many people have had good success with them.

 

[Stickseler]

That sounds kinda like what our tech geek came up with at work but it uses a nextel phone with GPS. It sends our trucks position every 30 secs or so we can track the trucks. They also got a barcode reader for the Nextel so we can track when and where the driver puts a load. I think there trying to get the phones to get some kind of data base so the drivers can use it to see where to drop stuff when they go back to the job.