Introduction
ECC stands for - 'Earth Conduction Communications' or 'Earth Current Communications'.
The fundamental principle of ECC utilises the inherent "resistance" of the earth. Signals are detected by a distant receiver by currents induced to flow through the earth at the receiver by the transmitter. It is these currents that can be used to communicate information to locations well outside the direct line between the two rods.
This principle has been used for more than 100 years and is by no means a new technique. The interest here lies in applying modern DSP techniques to extend the range of this communication mode.
Dedication
G0AKN - John Taylor was a contemporary practitioner of ECC at frequencies below 9kHz as well as 73kHz and 136kHz. Sadly John has passed away. His experiments can be found in this PDF file [470kBytes]. His work kindled my interest in ECC and his method of basic experimentation has set an good example to follow.
Motivation
From the discussion about attenuation elsewhere it can be seen that achieving significant distances utilising ECC communications is extremely difficult. As a guess, around 100Km will be the limit for true ECC (excluding electromagnetic radiation) at frequencies below 9kHz.
Firstly, the challenge of extending the range of ECC is attractive experimentally, especially using modern techniques.
Secondly, are the assumptions made above concerning the effects of transmitter/receiver probe configurations borne out in practice ?
Thirdly, there is a mountain of information waiting to be discovered surrounding this mode of communication. For example... Quantitative confirmation of the advantage of Dipole-Dipole configurations over Equatorial Dipole-Dipole configurations (or not) at ECC DX distances (> 10Km).
- Evaluation of transmitter probe configurations (i.e., what is the
effect of deep probes - down to 30m)
- What is the requirement for receiver probe spacing (i.e., minimum
distance required to overcome receiver noise - is this dependent on
local soil resistivity ?)
- What transmitter/receiver probe configuration is best for achieving
maximum range for a given power ?
- Is a triangular loop with one side on the ground as good and/or
convenient as earth probes as a receiving antenna ? (as suggested by
Mark - G0KZZ)