RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while tying up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
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and text used on the RF Cafe website are hereby acknowledged.
Wax nostalgic about and learn from the history of early
electronics. See articles from Radio & Television News, published 1919-1959. All copyrights hereby
In the days before satellite communications
(Telstar I, c1962), long-range television broadcasts relied
on an extensive (and expensive) series of line-of-sight microwave towers. Each site
had land ownership and maintenance expenses, so there was an incentive to streamline
operations. Development of an over-the-horizon relay system enabled a reduction
in sites and streamlining of operations - at least in theory. History shows that
these installations must not have provided the improvement needed to implement them
on a larger scale than that reported here. Nowadays, the proliferation of cellphone
towers for ubiquitous coverage of wireless telecommunications has proven that huge
numbers of individual sites can be profitable given a large enough customer base.
You can scarcely go anywhere anymore without being able to spy a cell tower sticking
out over the landscape.
First Over-Horizon TV Bridge
New 785-mile TV-telephone link set up between Florida and Cuba employs scatter.
One of four 60·foot "big screen" Blaw-Knox antennas used in new microwave scatter
Scientists and engineers at Federal Telecommunication Laboratories have developed
the world's first microwave radio system capable of carrying television and more
than 100 telephone channels for a distance of almost 200 miles. Over-the-horizon
microwave equipment, employing scatter techniques, provides an electronic bridge
between Florida City, Florida and Guanabo, Cuba - a distance of 185 miles. High-power
transmitters and high-gain antennas are used in the new link. The system differs
from others constructed or under construction in that it incorporates a frequency
band broad enough to accommodate television and more than 100 telephone conversations
at the same time. The conventional "O/H" system is narrowband and is capable of
carrying only a limited number of voice or telegraph channels. Overland links from
the O/H terminals to the main offices in Miami and Havana were installed by the
American Telephone and Telegraph Co.
In order to achieve the utmost in system reliability, broadband transmitters
and receivers are used in a suitable dual and quadruple diversity system. The equipment,
which is basically FM, operates in the 692-880 mc. band. A transmitter power level
of 10 kw. is used.
Besides this Florida-Cuba link, International Telephone and Telegraph Corp. is
installing five major O/H links. One joins the 240-miles-apart Mediterranean islands
of Sardinia and Minorca, providing direct telephone service between Spain and Italy.
President Kennedy addressing
the launch of the Telstar satellite
Posted November 10, 2021(original 10/31/2014)
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