The usual procedure is to tune a jamming transmitter onto the same channel as the incoming and supposedly undesirable broadcasts, and then modulate the jamming transmitter with noise, or music or noisy programming. In this way, it becomes very difficult or even impossible for listeners in the target country to hear the programming from the distant radio station.
Back during the era of the Cold War, shortwave listeners all around the world were aware of multitudes of jamming transmissions that were heard all across every international shortwave band. This annoying procedure began around the year 1948.
However, it was on the evening of November 29, 1988, that the Soviet Union ceased to jam all foreign radio stations. Thus it was that the extensive jamming era that lasted for 40 years was now over. It is stated that when the USSR switched off their massive network of jamming stations, they were operating more than 1600 jamming transmitters in about 120 jamming radio centers.
Radio
historians tell us that the earliest known jamming of radio broadcast
programming took place in the late 1920s.
During that era, Berlin was jamming the broadcasts of Radio Komintern in
Moscow.
At
that time, Moscow was on the air with 40 kW on 1450 metres (207 kHz) under the
callsign RA1. The antenna tower was the
famous and historic Shukov Tower, standing more than 500 feet tall that was
located for so long at 37 Shabolovskaya Street in Moscow.
However,
the story of the jamming of wireless transmissions goes back much further than
that. Back in the era of wireless
experimentation under the famous Guglielmo Marconi, it was discovered that two
wireless transmitters on the air at nearby locations at the same time succeeded
in turning the Morse Code signals of both transmissions into an unintelligible
mess, a hopeless garble. This was simply
an unintended case of jamming, due to the fact that the wireless emanations in
that era were untuned and very wide band.
In
September 1899, Marconi visited the United States at the invitation of the New
York Herald. It was arranged that he
would send out news releases in Morse Code on the progress of the 10th
America’s Cup, a yacht race between two contenders, the American “Columbia”
owned by the financier J. P. Morgan & the British “Shamrock” (1) owned by
Sir Thomas Lipton of tea fame.
In
order to cover the race as it proceeded off the coast of New Jersey, Marconi
placed wireless equipment on the ship “Ponce”, owned by the Puerto Line, and
the “Mackay Bennett”, a cable ship at anchor near the Sandy Hook
Lighthouse. During the three stages of
the race, lasting for 2½ weeks, Marconi successfully Morsed the information
back to the New York Herald. We might add,
the American contender, “Columbia” won the three successive events
outright.
Two
years later, there was a re-run of the same race at the same location between
the same two sparring partners, J. P. Morgan with his same “Columbia” and
Lipton with a newly designed yacht, the “Shamrock 2”. However, due to the success of the Marconi
news reports by wireless 2 years earlier, two other wireless companies got into
the act.
Marconi
equipment was installed into the ship “Mindora” with the landbased station
installed at the Navesink Twin Lighthouse, and news bulletins were Morsed
ashore for AP, the Associated Press.
Another
company, headed up by Lee de Forest, placed wireless equipment on an old
schooner, the “Maid of the Mist” which was towed around by the tugboat “William
J. Sewell”. The de Forest news bulletins
were Morsed ashore for the Publishers Press association.
In
addition the International Wireless Telegraph company also installed wireless
equipment on board ship and at a landbased location at Galilee in coastal New
Jersey. Morse code coverage from this
station did at times produce some form of jamming against the transmissions
from the Marconi & de Forest stations.
Initially
there was some on air squabbling between the Marconi & the de Forest
stations due to the fact that both temporary wireless stations were using
untuned equipment, but for the benefit of both, they worked out a mutually
agreeable sharing of time for their transmissions. Once again, the American “Columbia” was the
winner over the British “Shamrock 2”. However, two years later again, there was another running of the America’s Cup, the 12th since the original event in 1851, when the American yacht, “America” won the race around the Isle of Wight in the English Channel; hence the name, “America’s Cup”. In the 1903 event, the American yacht, “Reliance” owned by another financier Cornelius Vanderbilt was competing against the British “Shamrock 3”, owned still by Sir Thomas Lipton. During this event, there was at times some form of deliberate jamming apparently by a 3rd party.
Both
the American Marconi company and the Lee de Forest company placed wireless
equipment on ships hired for the occasion so that they could transmit news
bulletins back to the shore. However,
there was this 3rd contender, and it was Dr. Gustav P. Gehring and
his International Wireless Telegraph company with a powerful wireless station
at the Navesink Twin Lights Lighthouse.
It
was arranged in advance that the Gehring station would transmit long dashes in
Morse Code, and that the arrangement of these multiple dashes would indicate
various aspects of information associated with the yacht race. Even though these very long dashes in Morse
Code did signify news information, the real purpose was to jam the
transmissions for the other two news organizations, Associated Press &
Publishers Press Association. This
jamming transmitter succeeded in totally obliterating the news bulletins on
behalf of the two other news organizations, AP & PPA.The results of this 12th America’s Cup were that the American yacht “Reliance” won the three stages of the 1903 race, and neither AP nor PPA received any reliable news bulletins by wireless. This was the 1st known case of the deliberate and planned jamming of wireless transmissions, and it happened just 109 years ago, in the summer of the year 1903.
(AWR Wavescan/NWS 189 via Adrian Peterson)