I'm looking to transmit some data (CSV files) from a measurement instrument underground to a receiver on the surface. I've learned that in order to penetrate the limestone, low frequencies have to be used (around 80-130kHz). There are various methods to achieve this including ground-spike antennas that use the earth between two electrodes to help form a large antenna by injecting current into it, and magentic loop antenna pairs that essentially work as an inductor by transmitting and receiving the magnetic (H) component of the RF transmission rather than the low power E field component.
With that put aside, I've noticed that there aren't any existing RF modules that transmit at these frequencies. Because of that I've considered the posibility of directly synthesising a modulated signal using an Arduino (UNO or Nano). As far as I understand it I need a direct digital synthesis (DDS) IC to generate a reference frequency. From there I understand the Arduino can be used to calculate a waveform that simulates the modulation of that carrier in the mentioned frequency range. I've identified that on-off keying (OOK) would be a suitable modulation method due to its simplicity and resistance to noise.
This is where I need some help. How do I take a CSV file, use its contents to OOK modulate a carrier wave and then directly synthesise this waveform using Arduino? Are there libraries that already exist to enable this? If so, how would I use them? I don't have extensive programming knowledge so I'd appreciate any help I can get.