With Varying Frequency – Amateur Radio Ponderings

“In telecommunications, a diversity scheme refers to a method for improving the reliability of a message signal by utilizing two or more communication channels with different characteristics. Diversity plays an important role in combating fading and co-channel interference and avoiding error bursts. It is based on the fact that individual channels experience different levels of fading and interference. Multiple versions of the same signal may be transmitted and/or received and combined in the receiver. Alternatively, a redundant forward error correction code may be added and different parts of the message transmitted over different channels. Diversity techniques may exploit the multipath propagation, resulting in a diversity gain, often measured in decibels.”    - Wikipedia

Henry Rogers for the Western Historic Radio Museum has produced an excellent webpage on the development of Diversity Receivers for the Amateur Market by Hallicrafters Inc.

The DD-1 is unique for its era:

(click on picture or a larger version)

The math behind Diversity Reception is explained at Dr Paris’s website.

Tom W8JI also has a nice write up on Diversity Reception.

Thanks to Jeff KE9V for pointing out on his blog Long Delayed Echos the Western Historic Radio Museum website where the History of Diversity Radio for Amateurs is but a small part.

73

Steve 
K9ZW