Sending binary data over FM 144.650 MHz

Hi.

This is about a wheater balloon project.

I need to send low speed binary data from the ballon (10,000 meters max altitude) to a ham vhf receiver (FM 144.650 MHz).

I'm quite good for digital electronic, but not analog...

I think I need an oscillator and an amplifier, but I don't know exactly how to do it.

If anybody have an idea...

(the design must be really cheap, because chances of retrieving the balloon is poor)

Thanks

Might want to ask on a forum for Amateur radio enthusiasts for help on making radios.

I know theres kits and howtos out there on the internet for building FM transmitters, but typically they are low power and for a weather balloon you'll probably want to use a good amount of power.

You have the choice of sending AFSK (audio frequency shift keying) or carrier shift keying. Using AFSK is a lot easier to receive than simply changing the frequency. Especially at low bit rates.

Do you know what protocol you are going to use?

We are going to launch a weather balloon too.
We decided to buy a commercial radio.
Here are a few examples:
https://www.argentdata.com/catalog/product_info.php?cPath=25&products_id=110

https://www.argentdata.com/catalog/product_info.php?cPath=25&products_id=134&osCsid=d98dc78337fda42ae7b4f9290f9d1b49

From the software point of view, we maintain an RTOS which have an AFSK modem and AX25 layer ready to be used in order to send/receive APRS packets.

Here is an example project which uses an Arduino board to encode/decode APRS packets:

The required hardware is very minimal!