AX.25 (APRS) Remote Weather Station

Hey Arduino enthusiasts! I am a Mechanical Engineer (read programer handicapped) and am working on a remote weather station to support my local Paragliding/Kiteboarding community. We will be using a Young anemometer (pulse for wind speed and resistance for direction) at one of our favorite sites. We wanted to couple it with an Arduino to convert raw data into AX.25 audio that can be sent to a HAM radio and uploaded to the internet via a nearby igate. The programming for collecting the raw data should be straightforward but I was hoping for some help with the AX.25 (APRS) programing. I see there is a Radio Shield that can do it but was hoping to just use the PWM functions on the arduino. Thanks in advance for any help. Lastly, if it helps we have a little bit of money in the club account set aside that can be used to support the effort.

Here is some code that I think is near what I am looking for: Here is a description of weather APRS protocal (see page 62): Anemometer website: Radio shield I would prefer not to use: Who we are:

but was hoping to just use the PWM functions on the arduino.

Have you seen ANY projects that use PWM to generate audio data that is actually intelligible? Ever wondered why?

Paul, thanks for helping out! I too live in the Seattle area. The station will be going up near Port Townsend.

Using PWM to make waveforms makes sense in my head. But again it is an ME head and could be way off. The first website I listed ( ) saids this:

Use the hardware PWM of the Arduino to create the output wave forms using direct digital synthesis. Then Pass the output voltage from the PWM through a low pass filter using two poles (to get it nice and smooth).

What do you think?

What do you think?

I think that that is exactly what PWM is for.

However, audio is NOT nice and smooth. It is variable frequency, variable amplitude. Neither of which the Arduino can do. Using a radio shield, which has the necessary hardware to produce variable frequency, variable amplitude output is the way to go.