By Newcomb Weisenberger
Re: What did Marconi hear? By Donald Kimberlin nce, Radio Guide Oct. 2003
Read his excellent, thought provoking article.
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Some of the points made in the above article are: (In my own words)
The spark transmitter duty cycle was shortened so as to only produce clicks.
The existing propagation pattern made the transmission unlikely.
That atmospheric static mimicked the Morse code for the letter S
That Marconi so desired to hear an S that he imagined static signals were his
That Marconi’s experiment was “The World’s Most Heralded Radio Failure.”
The Kimberlin article is….. So provoking that I want to share these thoughts, which come to mind.
Note: Marconi wasn’t listening for three dots! He was listening for and heard an S
First, let us admit that neither you or I, or Mr. Kimberlin can know what Marconi heard in his earphones Dec 12 1903 nor why he said, “I hear England.” (Or words to that effect.) Nor would we know if we had been at his side 101 years ago.
Second, Place this event in context with his similar signaling experiments. The first was just over the hill at home. Others radiated at greater distances ’till he successfully crossed the English Channel. A serious engineer, Marconi changed one thing at a time. This time it was to determine if a radio link could compete with submarine cable. He placed his transmitter and receiver near the transcontinental terminals of the Anglo-American cable co. These were placed on the edges of the Atlantic Ocean. His goal was to move from signals to messages* again like cablegrams.
Marconi chose to receive. It is more difficult to receive than to send!
Note: This was one-way transmission. Marconi would develop Duplex messaging later
*Signals carry a meaning assigned by the sender. A character might be assigned that could carry the textual equivalent of a paragraph or more of copy. Marconi intended to, and later did, send text messages.
Writer’s comment: I believe that Marconi planned to make commercial use of his Radio Telegraph using his new Radiograms. ( Thought of then as Space messaging.) I believe that the Anglo American Cable Co. thought so too. And was motivated to evict him from their property. ( A fact that agrees that his experiment was a success at the time).
We can only imagine what an empty place the Radio spectrum was then. When Marconi wasn’t sending, there was no man-made signal on the air at any frequency! There was almost no man made interference! There were few homes wired for electricity. There were no electric appliances. Home wiring was for lighting only.
This void was filled with natural electro-magnetic radiation. Ancient from forever, but new in that man could now detect it! These signals were incoherent, bearing no intelligence. The cracks, pops and sizzles were a storm in them selves.
Marconi heard this like rain in his earphones. We call this random because there is no pattern to the thousands of discharges the world around.
(We make exception for sun spot cycles and fading.)
However, Random is a pattern in itself! A tapestry of gray noise with punctuating crackles of lightning. We now call this static, a name for brush discharges that can be seen, heard and felt without a radio receiver.
Marconi added an audible thread of electro magnetic radiation to this busy background. (A transverse EM Wave.) This was not random! But was a precise square wave. Digital before its time, in that time was more important than intensity.
Intelligence was also carried in the spaces between keying. ( Some 100 years earlier Mr. Morse had shared his code with the world.)
Note: Before Marconi, no sound was sent over the telegraph. The sound was, acoustic, created as the sounder was lifted and dropped. The timing of the clicks carried the information.
E I S H
One Dot, two Dots, Three dots, four dots
Signaling is the simplest method of communicating. This is what he and his assistant did, over and over again. We could repeat part of that experiment today. I could signal you while you listen to a background of static. (Like a hearing test.) The natural clicks are starting and ending in all possible variations. You can hear my signal though it is weaker than the static!
I will insert a code letter in the noise in your earphones. The human brain can detect and separate these letters from the random noise pattern. Marconi found that one dot or click is lost in the noise. Two clicks occur too often in the random pattern. Seldom do we hear three clicks in the noise.
By that we mean – space-click-space-click-space-click-space. We have produced a pattern of seven limiters that random noise rarely mimics. That is how complicated our S has become.
NOTE: Try to imagine how often in a 30 min period, that we can expect random static to appear with the precise timing and duration, followed by the proper period of silence to accidentally produce the letter S. Multiply those odds by the number of Ss sent.
Again, if at all odds three clicks were heard in Marconi’s earphones, it would not sound like Poldhue! (even if it was man made.)
We send a pattern of S’s at a scheduled time.
Marconi and his assistant have trained them selves to be so precise in the timing of their keystrokes that they can recognize the hand, (touch) of the sender. Not only can he hear an S or a series of S’s, but also he knows who is sending!
That he knew it came from Poldhu Station, England. That he could distinguish the pattern of S’s against the background noise.
Also, satisfied that this experiment was as successful as the experiments that preceded it and those that followed. The Anglo American Cable Co. felt so threatened by his successful experiment that they made him vacate their terminal property.
This experiment proved the sensitivity of his new magnetic detector. This would seem to be proof that Marconi could hear the S signal thru the natural noise. (Increasing the sensitivity of the receiver would have brought up the background noise too.)
We see little rational for Marconi to have:
Only thought He heard an S.
Nor that it was just wishful thinking.
That his success came from, to quote,
“The World’s Most Heralded Radio Failure.”
It follows that Marconi’s equipment was licensed to Naval Ships. I think that we can hear an echo of Marconi’ S in their international distress signal that used two Ss.
In 1901, Marconi had two things in his favor that no one has today.
Under these conditions, a fraction of a watt transmission can cross the continent.
+(Man made interference can be repetitive, natural interference is random )
The very nature of static is the sameness of its variables! When we hear it or see it, we are not aware of its unlimited variables but hear and see a ‘blanket’ of dis-interest.
A repetitive signal ‘stands out’ in contrast to the hash. Our brain automatically locks on to the information transmitted and ignores the natural background.
The unwanted atmospheric noise becomes the pallet for Marconi’s signal.
As we look back at the pattern of Marconi’s successful experiments and commercial rewards,
it seems unlikely that the successful Poldhue trial was only an illusion of a desperate inventor’s imagination. Or that this was an impossible dream shared by the World for one hundred years. nbw