Aviators also searched for a way to exploit the radio device to improve flying
safety. In 1920, thanks to a radio compass, US Navy seaplane pilots were able to
locate their position on a map during flight and head precisely towards a ship off
the coast of Virginia, which was emitting electromagnetic waves on a specific frequency. The crew then landed back on the airfield, calculating the route like they
had done before but this time tuning in to a station broadcasting from the airport.
Radio air navigation
10
made passengers and goods transportation safe and reliable; at the same time, it changed the balance of power among those nations that
could build large air fleets, which were capable of reaching enemy territories far
faster than ships. It was not long before the marriage between the Navy and the Air
Force was sealed. In 1922, the first aircraft carrier, the Japanese Hosho,
11
entered
into service, followed by the British Hermes the following year. From then on,
aircraft carriers became an indispensable military tool.
After WWII, a system of radio beacons, named LORAN (Long Range
Navigation), was installed all over the planet. The system was very similar to
today’s cellular mobile communication networks and transmitted radio signals on
specific frequencies depending on the geographical position. The onboard receivers could calculate the coordinates of an aircraft at any time by tuning into the
signal emissions of each specific cell of antenna, of which they had the position
and transmission frequency memorized.
12
Populations have been trying for thousands of years, amidst great tragedy and
enormous joy, to move around the world to fight, to trade and to survive. Then in
just a few hundred years, thanks largely to the invention of the clock and the radio,
everything changed. Historian Yuval Noah Harari writes:
It is estimated that the total value of the goods and services produced by
humanity in the sixteenth century was equivalent to about $250 billion in
today’s money. Today this value is close to $60 trillion. Also, in that century,
10
A radio signal transmitter-receiver system for determining location works as follows. Suppose
a transmitter is installed at a known point A on Earth and it disposes of a special radio that can
receive signals from transmitter A, whose position is known. When the signal is received, the
calculation of the distance from the place of transmission is immediate, but the position is not;
however, this is restricted to a single point on a circle with a radius of the above-mentioned
distance and with the location of the transmitter as the centre. So, by installing a second transmitting tower in another known point B, also on Earth, the same special receiver will also
measure the distance from B, and a second circle will be determined with the radius of the new
distance and with the transmitter B as the centre. The two virtual circles will have two points
of intersection, but only one will be the position sought. The introduction of a third repeater
provides a third circle intersecting the previous ones in a single point, corresponding to the
position sought. This method is the basis of today’s GPS satellite system.
11
http://www.difesaonline.it/evidenza/approfondimenti/la-marina-del-sol-levante-tra-le-dueguerre-mondiali-1918-1941.
12
Since LORAN transmitters send signals along the surface of the Earth, they only make it possible to calculate two-dimensional positions, i.e. latitude and longitude.
GPS: The Stellar Clock 55
safety. In 1920, thanks to a radio compass, US Navy seaplane pilots were able to
locate their position on a map during flight and head precisely towards a ship off
the coast of Virginia, which was emitting electromagnetic waves on a specific frequency. The crew then landed back on the airfield, calculating the route like they
had done before but this time tuning in to a station broadcasting from the airport.
Radio air navigation
10
made passengers and goods transportation safe and reliable; at the same time, it changed the balance of power among those nations that
could build large air fleets, which were capable of reaching enemy territories far
faster than ships. It was not long before the marriage between the Navy and the Air
Force was sealed. In 1922, the first aircraft carrier, the Japanese Hosho,
11
entered
into service, followed by the British Hermes the following year. From then on,
aircraft carriers became an indispensable military tool.
After WWII, a system of radio beacons, named LORAN (Long Range
Navigation), was installed all over the planet. The system was very similar to
today’s cellular mobile communication networks and transmitted radio signals on
specific frequencies depending on the geographical position. The onboard receivers could calculate the coordinates of an aircraft at any time by tuning into the
signal emissions of each specific cell of antenna, of which they had the position
and transmission frequency memorized.
12
Populations have been trying for thousands of years, amidst great tragedy and
enormous joy, to move around the world to fight, to trade and to survive. Then in
just a few hundred years, thanks largely to the invention of the clock and the radio,
everything changed. Historian Yuval Noah Harari writes:
It is estimated that the total value of the goods and services produced by
humanity in the sixteenth century was equivalent to about $250 billion in
today’s money. Today this value is close to $60 trillion. Also, in that century,
10
A radio signal transmitter-receiver system for determining location works as follows. Suppose
a transmitter is installed at a known point A on Earth and it disposes of a special radio that can
receive signals from transmitter A, whose position is known. When the signal is received, the
calculation of the distance from the place of transmission is immediate, but the position is not;
however, this is restricted to a single point on a circle with a radius of the above-mentioned
distance and with the location of the transmitter as the centre. So, by installing a second transmitting tower in another known point B, also on Earth, the same special receiver will also
measure the distance from B, and a second circle will be determined with the radius of the new
distance and with the transmitter B as the centre. The two virtual circles will have two points
of intersection, but only one will be the position sought. The introduction of a third repeater
provides a third circle intersecting the previous ones in a single point, corresponding to the
position sought. This method is the basis of today’s GPS satellite system.
11
http://www.difesaonline.it/evidenza/approfondimenti/la-marina-del-sol-levante-tra-le-dueguerre-mondiali-1918-1941.
12
Since LORAN transmitters send signals along the surface of the Earth, they only make it possible to calculate two-dimensional positions, i.e. latitude and longitude.
GPS: The Stellar Clock 55