the evolution of microwave communications
DESCRIPTION
A brief history of microwave communications by Richard Laine, Principal Engineer, Aviat Networks.TRANSCRIPT
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PRESENTED BY RICHARD U. LAINE, PEPRINCIPAL ENGINEER, AVIAT NETW ORKS, SANTA CLARA, CA 95054
EVOLUTION OF MICROWAVECOMMUNICATIONS - A BRIEF HISTORY
JULY 2011
Agenda
• Historical Perspective, not without controversy
• “Wireless” in its Infancy—the Intertwining of Edison, Marconi, andTesla
• Propagation—the Intertwining of Huygens, Newton, Fresnel, andEinstein
• Microwave Radios—The Early Days: PPM “digital,” Analog FM-FDM
• Evolution of the U.S. Microwave Communications Industry
• Evolution to Aviat Networks
• Upgrade from Analog to Digital Microwave Hops
• Digital Microwave Attributes—A Media Comparison
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY2
Wireless Communications – The Early Days
Excerpt from the Scientific American July 1892
In the specification to one of his recent patents,
Thomas A. Edison says:
“I have discovered that if sufficient elevation be obtained to
overcome the curvature of the earth’s surface and to reduce to
the minimum the earth’s absorption, electric signaling between
distant points can be carried on by induction without the use of
wires.”
MICROWAVE PATH ENGINEERING 117 YEARS AGO!
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY3
Thomas A. Edison (1847-1931)Ohio
The First Wireless Communications Age
The radio is one hundred years old, but it doesn’t look it!
... it is interesting to note that Samuel F. B. Morse’s telegraph was followed
only 40 years later by the increasingly remarkable invention of radio
frequency transmission.
Thomas Edison experimented with signals that could be generated and
detected at a distance in 1883, but did not appreciate the importance of
“the Edison Effect.” Edison received a patent for wireless telegraphy in
1885, but was preoccupied with other projects. Edison sold the patent “for
a song” to Marconi, who put extensive effort into the technology. By 1901,
he sent Morse Code from Massachusetts to Cornwall, England.
Roger Rusch
Applied Microwave & Wireless Fall 1995
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY4
Samuel F. B. Morse (1791 – 1872) Scotland
Wireless – Marconi Inventor of the Radio?
January 1897An invention which promises to be of the greatest practical value in the world of telegraphy hasreceived its first public announcement at the hands of Mr. William H. Preece, the telegraphicexpert of the London post office. During a lecture on "Telegraphy Without Wires" recentlydelivered in London, Mr. Preece introduced a young Italian, a Mr. Marconi, who, he said, hadrecently come to him with such a system. Telegraphing without wires was, of course, no newidea. In 1893, telegrams were transmitted a distance of three miles across the Bristol Channel byinduction. Young Marconi solved the problem on different principles, and post office officials hadmade a successful test on Salisbury Plain at a distance of three-quarters of a mile.
Scientific American - January 1897
The roots of modern radio-links can be perceived in the first experiments carried out by Marconi,as he used very high frequencies—practically in the field of microwaves—and had recourse toparabolic-cylinder reflectors. Here is the first invention which Marconi anticipated. Many scientistsbefore Marconi had devoted their work to the electric and magnetic phenomena, takingadvantage of the extraordinary synthesis which James Clerk Maxwell’s equations had giventhem. In 1894, when he was only twenty, the young man from Bologna set up his first laboratoryat Villa Griffone, about fourteen kilometers from his native city. Marconi’s basic contribution, forwhich he deserves the name of “inventor of the radio”, was, first of all, that he modulated by asignal the electromagnetic waves that a spark produced in a Hertz oscillator sent in space.
Gian Carlo Corazza 1996 European Conference for Radio-Relay, Bologna
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY5
Guglielmo Marconi(1874-1937) Italy1909 Nobel Prize for Wireless Telegraphy
James Clerk Maxwell(1831-1879) Scotland
Wireless – Marconi Inventor of the Radio? Or Not!!
On 11 June 1943, the U.S Supreme Court overturned most of Marconi’s
wireless communications patents thus upholding Nikola Tesla’s earlier
September 1897 patent for radio, that in 1904 was reversed by the U.S. Patent
Office and awarded to Marconi, based upon Tesla’s wireless communication
demonstrations in 1894.
This Supreme Court decision—five months after he died impoverished, alone
in a New York hotel room—in effect recognized Tesla (who, shortly after
arriving in the U.S. in 1884, had worked for Thomas Edison for $18 per week)
as the inventor of the radio.
This added to Tesla’s remarkable credentials as the inventor and architect of
alternating current machinery and long-distance electrical distribution, this
rendering obsolete his adversary Edison’s direct current electrical
powerhouses that had been built up and down the Atlantic seaboard.
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY6
Nikola Tesla (1856-1943) Austrian Empire“The Man who Invented the 20th Century”
Propagation – Huygens’ Principle? Or Not!!
Christiaan Huygens, a contemporary of Sir Isaac Newton, is said to have gained most of his insights into wave motion by
observing waves in a canal. In 1678, this great Dutch physicist wrote the treatise Traite de la Lumiere on the wave theory of
light, and in this work he stated that the wavefront of a propagating wave of light at any instant conforms to the envelope of
spherical wavelets (Huygens’ “Combination Wavefront” of separate waves) emanating from every point on the wavefront at
the prior instant, with the understanding that the wavelets have the same speed as the overall wave.
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY7
Augustin-Jean Fresnel(1788-1827) - France
Albert Einstein(1879-1955) - Germany
Christiaan Huygens(1629-1695) - Netherlands
Sir Isaac Newton(1643-1727) - England
Propagation – Huygens’ Principle? Or Not!!
An illustration of this idea, now
known as Huygens' Principle, is
shown. Disbelieving, Newton
continued to push his “Corpuscular
Theory” of particle propagation of
light, so because of that it was not
until some 100 years later when
Augustin-Jean Fresnel of “Fresnel
lens” and “Fresnel zone” fame
revisited Huygens’ Principle in 1815
that his term “diffraction” was
reintroduced.*
JULY 20118 EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY
Einstein and others opine the dualitythat light functions as both a particle(per Newton) and a wave (perHuygens) depending on how theexperiment is conducted and whenobservations are made.
Illustration of Huygens’ Principle.The pinholes in the mask act assecondary point sources of radioenergy.
Microwave Radio Links - The Early Days
2 GHz PPM “Digital” Radios
6 Bays!! 24xVF or 24x300 baud data channel capacity!! General Electric’s
2 GHz “radar-like” pulse position modulated (PPM, used during WW2 then
declassified) hot standby terminal. Many hundreds of similar GE and ITT
PPM radio hops were deployed in long pipeline, power and turnpike
systems in the 1940s-50s, some up to 75 hops in length with no end-to-
end noise buildup (like modern digital systems), all over the U.S. and
worldwide for the military.
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY9
Microwave Radio Links - The Early Days
AT&T Long-Haul Analog Routes Deployed 35,000 TD2 Repeaters
The San Francisco-New York transcontinental route of hundreds of 4 GHz
TD2 analog FM-FDM hops completed in 1951 for all long distance VF and
TV was upgraded with high-capacity L6 GHz TH1 radios in 1955 and
improved TD3 radios in 1962.
The performance of analog hops was far more
affected than later generation digital radio hops
to equipment nonlinearities, interference,
thermal noise, multipath distortion,
waveguide echoes and moding,
and fading.
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY10
U.S. Microwave Industry Evolution Through 1991
The Early DaysU.S. Microwave CommunicationsManufacturers from 1931 (ITT) through 1991
Farinon/Harris MCD (1958) andDMC/Stratex Networks (1984) merged to formHarris Stratex Networks (2007), which changed names toAviat Networks (2010)
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY11
EXTINCT
50EXTINCT
50EXTANT
20(growing rapidly)
EXTANT
20(growing rapidly)
JULY 201112 EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY
How We Evolved into Aviat Networks
JULY 201113 EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY
1963
1982
1984
Jan 1984San Jose
2002
Microwave CommunicationsDivision (MCD)
1980Merger
1981
1998
Feb 1958San Carlos
Jan 26, 2007 Merger
SiemensTransmission Systems
Lenkurt Electric Company
GTE Network Systems
Len EricksonKurt Appert*
1959 Merger
1944 San Francisco1947 San Carlos, CA
1983
Siemens Information andCommunications Networks
Boca Raton* Bancroft Library Oral history: http://www.archive.org/search.php?query=kurt%20appert
Bill Farinon
Bill Gibson
)(
2010
The Migration from Analog to Digital Microwave Links
It’s Been a Challenge!
• Canadian Marconi delivered the first PCM digital radios to privatemicrowave users in North America in 1970, some hops remaining inservice into the millennium, thus triggering the rapid development anddeployment of higher capacity (first 1152 VF ch/78 Mbit/s, then 1344 VFch/90 Mbit/s) digital radios for LOS (line-of-sight) radio-relay hops.
• This culminated in 1980 with the realization that the alarm/networkmanagement systems and adaptive equalization in these trailblazingdigital radios were often found totally inadequate to accommodate thefragile, bursty characteristics of many high capacity digital microwaveradios and spectral distortion caused by dispersive fading in hops notbefore seen in FM-FDM analog radio systems.
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY14
The Migration from Analog to Digital Microwave Links
It’s Been a Challenge!
• The 1980s thus brought about dramatic improvements in digitalmicrowave modulation efficiencies and, with new adaptive equalizationand powerful error correction, robustness to the dispersive (spectrum-distorting) fade activity that so degraded digital radio hop performance inthe 1970s.
• The mid-1990s heralded DSP equalizers that replaced discrete devicesin far more robust advanced asynchronous (PDH) and 2016/1890 chSONET/SDH point-to-point TDM digital radios. The FCC’s relocation ofanalog microwave hops from 2 GHz in the late 1990s to accommodatecellular deployment sped this digital migration.
• These new PDH and SDH digital technologies supported the explosivebirth of new high-performance terrestrial Fixed Wireless Systems andFixed Wireless Access networks in all of their forms, e.g. Point-to-Pointand Point-to-Multipoint, in synergism with fiber optics and FSO (free-space optical) networks.
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY15
Digital Microwave Attributes - a Media Comparison
• Superior availability (“uptime”) —route security (no fiber optics cable cuts)
• Rapidly expandable and upgradeable, in-service if protected
• High quality—no multihop “noise” addition as in analog microwave hops
• Rapid deployment over difficult terrain and into urban areas, unlike cable
• Economical and secure—no copper or fiber optic cable deployment withright-of-way and security issues, and very high costs
• Robust to fading and interference compared to analog microwave hops
• Much less sensitive to antenna feeder system and long-delayed ,on-pathechoes compared to analog microwave hops
• Highly efficient data and broadband transport
• Exacting in-service visibility of radio hop performance with NMS, PCR
• Seamless interconnectivity to an ever-expanding digital transport (fiberoptics and other), PABX/MSC switch, and LAN/IP world
JULY 2011EVOLUTION OF MICROWAVE COMMUNICATIONS: A BRIEF HISTORY16
FavorsMicrowave
Microwave or Fiber
FavorsFiber
Required Transport CapacityLow
Long
Transport ChoicesShort
Turn
-Up
Tim
e
High
Radio Fiber
Availability/security Payload (transport) Cost effectiveness Implementation time Terrain considerations