Broadband via the Earth

by saint  (saint@peachworld.com)

For the average Internet user, or the computer experimenter; the thought of having access to a high-speed data link is what dreams are made of.  Broadband data transfer would allow a world of applications to be run on a Local Area Network (LAN).  Broadband data transfer would also mean pretty hefty transfer speeds to the Internet.  Without access to dedicated wired connections, or wireless modems, can this concept become a reality?

Nortel has recently introduced a method of distributing computer network signals via standard electrical wiring.  This is re-application of old technology, with a new twist.

For many years, colleges and various institutions used electrical power lines to "broadcast" radio signals to listeners within a limited area.  Types of modulation varied, with both AM and FM modulation being used.

The Intercollegiate Broadcast System (IBS) discusses such a system in their 1978 Master Handbook for college radio stations.

There are a few limitations to this system however.  The greatest limitation is the need for relay stations at each electrical substation.  Radio frequency data cannot be pushed up through the substation transformer array, due to impedance and other electrical factors.  The next limitation is the noise generated and carried on the actual electrical power line.  Electrical lines are designed and built to carry electricity and not radio frequency data.

Looking back into the lost pages of history, there may be yet a more promising avenue of approach.

Imagine using good old Mother Earth as a huge conduit for data streams.  Impossible, you say.  Well, let's look back in time.

Chapter 1

The first prominent chapter is the great experimenter and visionary, Nikola Tesla.

Tesla was among the greatest inventors of the late-1800s and early-1900s.  His work far superseded that of John Lodgie Baird, Guglielmo Marconi, and Thomas Edison.

Tesla envisioned a system where unlimited power could be transmitted through the Earth.  In 1899, at his laboratory located in Colorado Springs, Colorado, Tesla succeeded in sending electrical current through the ground, and produced magnificent man-made lightening as a result.  One of the most dramatic occurrences of this particular experiment was that the equipment used to introduce the electrical current into the Earth worked so well that the generating station in Colorado Springs was set on fire due to "continual feedback" from the induced electrical current into the Earth.  Remember the basic system of radio operation - the antenna and ground system.  Tesla was also able to correlate information and determine the natural frequency of the Earth.  I believe this frequency is 33 kHz.

Here is proof positive that electrical current can be transmitted through the Earth, and that the electrical waves can travel at distances beyond a mere few feet.

Chapter 2

The second prominent chapter is during (((World War 1))).

Wireless sets were not readily available for deployment to ground forces.  It was, and still is, vital for communications to be constantly available for commanders to direct operations.

The method of combat in WW1 was trench warfare.  Long miles of trenches marked each side's area of operation.  Real time communication was essential, as human and pigeon couriers were not immune to the implements of the opposing side's arsenal.

The French used a primitive version of the modern field telephone.  Their system consisted of the standard telephone handset and signal generator.  (The signal generator would alert the other user that a telephone call was coming through.  Much like the modern ring of a telephone.)

The variant that the French had was that in lieu of using wires to connect the telephones, they used the Earth as a conductor.  This method was used for a short while until the Germans developed a sensitive audio amplifier that they employed on their side of the trenches.  (It is important to remember that the opposing sides' trenches were often miles apart, with various earth conditions separating the two.)  The Germans would intercept and monitor the "ground" signals that the French were sending out through their "Earthen" field telephone system.  The French countered by employing a single ground and wire connection, thus limiting the electrical current sent via the ground portion of their field telephone system.  They also used a vacuum tube oscillator, which generated "white noise" or random electrical current that would mask the grounded side of their field telephone system.  The Germans were thus denied the ability to monitor the French Earthen audio.

Chapter 3

During (((World War 2))), U.S. amateur radio operations were forbidden and outlawed by the cognizant authority.  The federal government was fearful that the axis powers would monitor these communications and receive valuable intelligence.

The ever resourceful amateur radio operator turned to conducting local "nets" via Earthen audio communications.  The basis was exactly identical to what the French had used in their "Earthen" field telephone system.

Modern Day

In Modern Electronics magazine (September 1990), a detailed description of "A Ground Communication System" is discussed.  The basis for this system is a mic, audio preamplifier, stereo amplifier, and a transformer, for the "transmitter" portion of the system.  The input is naturally the mic.  The preamplifier boosts the audio data from the mic to the stereo amplifier.  The transformer acts as an impedance match to match the amplifier to the grounded element.

The receiver portion consists of a transformer, amplifier, and a speaker.  The operation consists of the transformer matching the impedance of the grounded receiving rod to the transformer.  The amplifier passes on the received data to the speaker.

Ground methods considered were various.  A quick check of the American Radio Relay League (ARRL) handbook would provide a more detailed explanation and selection of ground schemes.

Ground element spacing would have to be plotted for each individual station.  Ground composition, water table, and subsurface structures (metal water or sewer pipes) would radically affect the "ground radiation" pattern.  You would want to achieve maximum electrical potential, to achieve the maximum transfer of electrical current to attain the most usable communications range.

We have established a "grounded Earth" audio link, so what?  How does your modem work?  That's right, good old audio.

The standard, unconditioned telephone line has an audio spectrum of 30 Hz to 3000 Hz.

Now then, imagine setting up your computer modem to communicate via your "grounded Earth" telephone link.  You could develop your own community based BBS, without having to involve Ma Bell.

Unlike telephone lines, where lines must be conditioned to maximize binary data transfer, an Earthen ground data communications system would have no such electrical devices to impede spectrum usage.

The only drawbacks to such a system would be:

Electrical Noise:  Much like the French using their audio oscillator to generate random electrical noise, the modern household radiates abundant electrical hash and trash into the surrounding ground - through the electrical companies' grounded feeder box.  Don't forget the telephone company, cable company, and your own amateur radio station equipment.  You would have to use a software or hardware based digital signal processor to filter out the unwanted electrical noise.  Remember that we are dealing with binary data transfer, and random electrical noise can effectively reduce the speed of your data link.

Range:  Depending on the ground system used and the condition of the soil where you place your Earthen ground system, your actual mileage will vary greatly.  The one factor in your favor: there is no limit on the amount of electrical current that you can pump into the Earth.  (Just remember that any electrical current that you feed into the ground can have the potential of leaking back into the household ground on your electrical feeder box, cable TV ground, and the telephone ground.  Another consideration is that you don't want to feed too much electrical current into the ground that would cause an electrocution hazard to humans or pets.)

Privacy of Information:  Private information flowing through this data link could be a factor.  (Remember, just as the Germans did in WW1, anyone could monitor this data - and view it.)

Virtual Private Networks:  Microsoft and several other companies have developed a software solution to this problem.  In essence, through a VPN, you establish a secure (encrypted) data flow between your computer and the host computer over an existing computer network.  Through such a system, you can exchange data without the fear of compromising data.

Bandwidth:  I have no idea what kind of bandwidth such a system could offer.  The least amount of bandwidth would be comparable to the standard 56 kbps modem.  I am sure that bandwidth limitations would vary, due to soil content and related factors.

What Would a Total Ground-Based Communications System Cost?

If you were to scrounge enough, you could probably assemble the necessary hardware for less than $200.00 (both the send and receive portion, or a complete system).

Unlike standard RF communications, ground communications is not affected by atmospheric anomalies or propagation.  Unlike the telephone system, your ground wave communications link would never be "Out of Service."

Happy experimenting.