Avionics News May 2013 - 61

Avionics and a radio operator onboard the
Fokker C2, a test bed for communication
and navigation equipment.

Photo courtesy of The Museum of the Air Force

40 years before the AEA’s founding. In the early years, pilots did
not find radios particularly useful. In fact, many pilots preferred
the old method of writing messages and then dropping them over
the side of the airplane.
The basic concept of avionics communication has remained
unchanged. The primary communication radios in aircraft
remain of the AM type. In time, the frequencies have been raised
and the bandwidth has been narrowed, but the basic concept has
remained the same.
Radio Navigation Prior to World War II
One of the driving forces behind the development of avionics technology was the industry’s need for accurate navigation.
Deduced reckoning, celestial navigation and navigation by pilotage have limits. As instrumentation developed, allowing aircraft
to fly in reduced or no-visibility conditions, the need for accurate
navigation grew.
An early form of radio navigation was the direction finder, also
called the radio direction finder. As early as 1922, aircraft have
been equipped with RDFs. The most common RDF design consisted of a rotatable loop antenna on the aircraft fuselage. A radio

operator could tune in a radio station and obtain a line of position.
Through the use of triangulation, exact positions could be determined. The DF was the new navigational technology of the 1930s.
Some experts claim that if Amelia Earhart’s (1897-1937) navigator, Fred Noonan (1893-1937), had been more familiar with the
Electra’s RDF, Earhart and Noonan would never have been lost.
Also available in the 1930s was the radio compass. The U.S. Army
Air Corps performed radio compass testing in 1931.
The use of RDF and its successors, the radio compass and ADF,
presents challenges for pilots, since both systems report a bearing
to the station relative to the aircraft. As a result, pilots using DF
technology must estimate and correct for winds aloft. This process
can be difficult, even for the most experienced pilots.
Concurrent with the development of RDF was range technology, also called reverse RDF. In 1929, the French developed
a rotating wireless beacon. In this case, a directional antenna
would rotate through 360 degrees, once each minute. When the
antenna pointed north, the station would broadcast an identification signal. A radio operator onboard the airplane could measure
Continued on following page
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Avionics News May 2013

Table of Contents for the Digital Edition of Avionics News May 2013

Point of Communication
AEA now
The View from Washington
International News and Regulatory Updates
Beltway Briefing
Power Redundancy in the Age of Digital Cockpits
Member Profile
Capital Quest
Avionics News Through the Years
Equipping for International Operations
A Conversation With...
Member Profile
What is Australia Waiting For?
AEAviators
Going Global
Business Basics
The History of Avionics
Meet the AEA Board of Directors
A Real-Time Look at Airborne Weather Radar
Aviation Aces
Legal Ease
What's New
Marketplace Classifieds
Avionics News May 2013 - Intro
Avionics News May 2013 - Cover1
Avionics News May 2013 - Cover2
Avionics News May 2013 - 1
Avionics News May 2013 - 2
Avionics News May 2013 - 3
Avionics News May 2013 - Point of Communication
Avionics News May 2013 - 5
Avionics News May 2013 - AEA now
Avionics News May 2013 - 7
Avionics News May 2013 - 8
Avionics News May 2013 - 9
Avionics News May 2013 - 10
Avionics News May 2013 - 11
Avionics News May 2013 - 12
Avionics News May 2013 - 13
Avionics News May 2013 - The View from Washington
Avionics News May 2013 - 15
Avionics News May 2013 - International News and Regulatory Updates
Avionics News May 2013 - 17
Avionics News May 2013 - 18
Avionics News May 2013 - Beltway Briefing
Avionics News May 2013 - Power Redundancy in the Age of Digital Cockpits
Avionics News May 2013 - 21
Avionics News May 2013 - 22
Avionics News May 2013 - 23
Avionics News May 2013 - Member Profile
Avionics News May 2013 - 25
Avionics News May 2013 - 26
Avionics News May 2013 - 27
Avionics News May 2013 - Capital Quest
Avionics News May 2013 - 29
Avionics News May 2013 - 30
Avionics News May 2013 - 31
Avionics News May 2013 - Avionics News Through the Years
Avionics News May 2013 - 33
Avionics News May 2013 - Equipping for International Operations
Avionics News May 2013 - 35
Avionics News May 2013 - 36
Avionics News May 2013 - 37
Avionics News May 2013 - 38
Avionics News May 2013 - 39
Avionics News May 2013 - A Conversation With...
Avionics News May 2013 - 41
Avionics News May 2013 - Member Profile
Avionics News May 2013 - 43
Avionics News May 2013 - 44
Avionics News May 2013 - 45
Avionics News May 2013 - What is Australia Waiting For?
Avionics News May 2013 - 47
Avionics News May 2013 - 48
Avionics News May 2013 - 49
Avionics News May 2013 - AEAviators
Avionics News May 2013 - 51
Avionics News May 2013 - Going Global
Avionics News May 2013 - 53
Avionics News May 2013 - 54
Avionics News May 2013 - 55
Avionics News May 2013 - Business Basics
Avionics News May 2013 - 57
Avionics News May 2013 - 58
Avionics News May 2013 - 59
Avionics News May 2013 - The History of Avionics
Avionics News May 2013 - 61
Avionics News May 2013 - 62
Avionics News May 2013 - 63
Avionics News May 2013 - Meet the AEA Board of Directors
Avionics News May 2013 - 65
Avionics News May 2013 - 66
Avionics News May 2013 - 67
Avionics News May 2013 - A Real-Time Look at Airborne Weather Radar
Avionics News May 2013 - 69
Avionics News May 2013 - 70
Avionics News May 2013 - 71
Avionics News May 2013 - 72
Avionics News May 2013 - 73
Avionics News May 2013 - Aviation Aces
Avionics News May 2013 - 75
Avionics News May 2013 - Legal Ease
Avionics News May 2013 - 77
Avionics News May 2013 - What's New
Avionics News May 2013 - 79
Avionics News May 2013 - 80
Avionics News May 2013 - 81
Avionics News May 2013 - Marketplace Classifieds
Avionics News May 2013 - 83
Avionics News May 2013 - 84
Avionics News May 2013 - Cover3
Avionics News May 2013 - Cover4
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