"Radio Astronomy and Satellite
Communication, two N.J. first
Whenever we touches history, events of the past belong to the present
Electrical Engineer Luis A. Riesco, IEEE Life Senior Member
Consulted:
1. IRE Proceedings, yrs. 1932 & 1935 KG Jansky
2. My Brother KG Jansky an his discovery…yr. 1936 CM Jansky 94th meeting A.A.Soc.
3. NASA Science educational publications
4. INFOAGE Museum and Partners Ocean Monmouth Radio Club OMARC and IEEE
5. The Evolution of RADIO ASTRONOMY , J.S. Hey 1973 Science History Publications
6. IEEE CENTENIAL JOURNAL, NJ Coast Section , 9 March 1984
7. THE INVISIBLE UNIVERSE, The Story of Radio Astronomy, Gerrit L. Verschuur
8. HIGHER FREQUENCY TECHNIQUES, Departments of the Army and Air Force, 1952
9. IEEE AEROSPACE and ELECTRONIC SYSTEM MAGAZINE Vol.3 No.12, DEC. 1988
Copyrights by respective organizations and Ideas Unlimited, Corp.
All copy rights reserved
10/7/2010
1
Radiation from deep space detection PART 1
Radiation through space and back PART 2
• We will recreate these New Jersey first into
the present in such a way that you will
understand how these science pioneers
handled basic communication and space
principles with hard work, determination and
ingenuity.
• We will use decimal units as used in common practice.
10/7/2010
2
RADIO and RADAR Radio Detection And Ranging
•
Basic foundation originated in Europe
•
Michael Faraday (1791-1867) Electric magnetic field around a conductor
James Clerk Maxwell (1831-1879) Mathematical model for electromagnetic waves propagation
Heinrich Hertz ( 1857-1894) Demonstrated the existence of electromagnetic waves
Guglielmo Marconi (1874-1937) Built wireless apparatus and Patented in England
•
US patents for elementary wireless apparatus has been granted to a number of researchers
Thomas A. Edison (1891) ; Oliver Joseph Lodge (1894); Nikola Tesla (1897) Worked at Edison Power
Station then Joined Westinghouse and then started his own company.
such as:
•
US Supreme Court overturned Marconi’s patent and in 1943 credited Tesla with the invention of Radio.
However Marconi excel as businessman and soon became a world radio communication monopoly with Marconi’s
Wireless Telegraph Company. Made demonstration to the British and US Navy and Transoceanic communication.
•
Initial wireless technology used the spark gap principle before Hertz to Tesla,
Marconi and others.
•
The history of radio shows that the spark gap transmitter was the product of many people,
often working in competition. Battery energy was transferred to a coil and a capacitor as a spark
jumped the space oscillates and discharged into an antenna that irradiates a radio signal.
10/7/2010
3
The Circle as a Sine Wave Generator
•
http://upload.wikimedia.org/wikipedia/commons/a/a5/ComplexSinInATimeAxe.gif
•
Circle radius r=1
•
Axes x,y and z=time
•
The 360 degree circle
•
Wavelength λ Lambda, measured between any two repetitive points, such as crests,
or repetitive zero crossing.
•
Propagation through free space occurs at a velocity of nearly 300,000 km/sec.
•
f is the frequency of oscillation in Hz/sec.
•
c the velocity of propagation of electromagnetic radiation in m/sec.
•
Then we have:
c= f λ or
λ m)=300/f(MHz)
10/7/2010
4
Electric and magnetic fields in an
Electromagnetic wave
10/7/2010
5
Electromagnetic Spectrum
f (GHz)
λ (cm)
L
30 –15
1–2
S
15 - 7.5
2-4
C
7.5 - 3.75
4-8
X
3.75 - 2.4
8 - 12
K
2.4 - 0.75
12 - 40
Microwave Bands
These are ballpark values
10/7/2010
6
Electrical wave generation
•
The capacitor is fully charged and there is no current passing through the coil. This
situation is unstable and the capacitor spontaneously discharges via the coil,
creating a current in it which is linked with a magnetic field. The energy stored in the
capacitor (potential energy) is exchanged for the energy associated with the
magnetic field and flowing current (kinetic energy) in the coil. In other words, the
capacitor is the generator, and the coil is the load.
•
The current flowing in the coil is at a maximum and so is the associated magnetic
field. The capacitor is fully discharged. Unfortunately, because of this, at this very
moment the power supply fails. The situation is unstable. The current flow ceases
momentarily, the magnetic field gradually collapses, and a current is induced in the
coil, passes out of the coil and charges up the capacitor. Kinetic energy is
exchanged for potential energy, the above formula is effectively written the other way
around,
•
now the coil has become the generator and the capacitor has become the load.
•
Since the impedances of coil and capacitor are conjugate, the maximum power is
transferred from (transferred from, not consumed by!) one to the other at the
condition of resonance.
•
If there was no resistance in the circuit, this exchange or oscillation would continue
indefinitely because the current and voltage are out of phase in each branch of the
circuit and no power is consumed; the damping and decrement would be zero and
the Q infinite. Some how this circuit deliver the oscillation and a Power Supply
sustain the oscillation.
10/7/2010
• If the resistance in a tuned circuit is negligible, then the resonant
7
RADAR Astronomy active observation
• Radar astronomy is a technique of observing nearby
astronomical objects by reflecting microwaves off target
objects and analyzing the echoes. This research has been
conducted for four decades. Radar astronomy differs from
radio astronomy in that the latter is a passive observation and
the former an active one. Radar systems have been used for a
wide range of solar system studies. The radar transmission
may either be pulsed or continuous.
• The strength of the radar return signal is proportional to the
inverse fourth-power of the distance. Upgraded facilities,
increased transceiver power, and improved apparatus have
increased observational opportunities.
10/7/2010
8
Radar detection principles and uses
•The speed of an object is measured by applying the Doppler principle.
•Object approaching the radar antenna, the frequency returned signal
is greater than the frequency of the transmitted signal.
• Object is receding from the radar antenna, the returned frequency is
less.
• Object is not moving relative to the antenna, the return signal will have
the
same uses
frequency
as traffic
the transmitted
signal.
•Primary
is in air
control, where
airports use radar to track
airplanes and for navigational and weather determination purposes.
Military radar detects the enemy and guide defense weapons.
•Scientific study of the solar system. Used for basic orbit determinations
measuring distance and speed versus time. Rendering data into a radar
image. These techniques can also be applied from a spacecraft radar,
flying past a solar system object or in orbit, around the object. With this
new area of astronomy, hundreds of special bodies in the solar system
have been studied by radar to map out their surface, measure their
distance from earth, and to follow their orbits that allows present10/7/2010
and
9
future space travel landing and return
Lt. Col. John H. DeWitt, Signal
Corps Evans Signal Laboratory
Director.
W4ERI
• Born in Nashville, attended Vanderbilt University
Engineering School for two years. Vanderbilt did not
offer electrical engineering, so DeWitt dropped out
in order to satisfy his interest in broadcasting and
amateur radio.
• After building Nashville's first broadcasting station,
in 1929 DeWitt joined the Bell Labs NY City,
designing radio broadcasting transmitters.He
returned to Nashville in 1932 as Chief Engineer of
radio station WSM.
10/7/2010
10
State of the art and Project
•On the night of 20 May 1940, using the receiver and 80-watt
transmitter configured for radio station WSM, DeWitt tried to reflect
138-MHz (2-meter) radio waves off the Moon, but he failed due to
insufficient receiver sensitivity.
•Intrigued by Karl Jansky's discovery of "cosmic noise," DeWitt built a
radio telescope and searched for radio signals from the Milky Way.
•190-120 BC Hipparchus from Alexandria trigonometry developer, made estimates of the solar system geometry.
He new earth’s radius was about 4000 miles and found the Moon distance to be about 60 radii.
•240000 miles or 386,160 Km. Today depending of position of Moon orbit, between 360,000 and 405,000 Km
NASA. Taking the average 382,500 Km, for an earth diameter of 12 756.2/2= radius 6378.1 Km.
•or 59.97 earth radii, a tolerable approximation for that time.
• DeWitt then received a directive from the Chief Signal Officer, the
head of the Signal Corps, to develop radars capable of detecting
missiles coming from the Soviet Union. “No test missiles were
available, so the Moon experiment stood in their place” DIANA was
born. Abundant radar surplus equipment and funds to achieve a 10/7/2010
goal
11
he had long cherished.
“Radar was developed by men who were familiar with the ionospheric
work.
using widely-known scientific technique, which explains why the
development of radar--took place simultaneously in several different
countries."
In September 1945, DeWitt assembled his team:
Dr. Harold D. Webb, Herbert P. Kauffman,
E. King Stodola, and Jack Mofenson.
Dr. Walter S. McAfee, in the Laboratory's
Theoretical Studies Group, calculated the
reflectivity coefficient of the Moon.
Members of the Antenna and Mechanical Design,
Research Section, and other Laboratory groups.
10/7/2010
12
Basic equipment selection criteria
• No attempt was made to design major components
specifically for the experiment. The selection of the receiver,
transmitter, and antenna was made from equipment already
on hand, including a special crystal-controlled receiver and
transmitter designed for the Signal Corps by radio pioneer
Edwin H. Armstrong.
•
Crystal control provided frequency stability, and the apparatus
provided the power and bandwidth needed.
• The relative velocities of the Earth and the Moon caused the
return signal to differ from the transmitted signal by as much
as 300 Hz, a phenomenon known as Doppler shift. The
narrow-band receiver permitted tuning to the exact radio
frequency of the returning echo.
10/7/2010
13
Anticipating receiver design criteria
As DeWitt later recalled:
• "We realized that the moon echoes would be
very weak so we had to use a very narrow
receiver bandwidth to reduce thermal noise to
tolerable levels.
• We had to tune the receiver each time for a
slightly different frequency from that sent out
because of the Doppler shift due to the earth's
rotation and the radial velocity of the moon at
the time."
10/7/2010
14
Shortly after V-J Day, Lt. Col. DeWitt issued instructions
to modify certain standard radar equipment for the moon
investigation.
•
Changes to allow us to send out a long pulse. The
transmitter was driven as hard as possible so we
could get considerably more power from it, and an
ordinary telegraph key was connected in the circuit
to turn it on and off.
•
It was decided that a one-second pulse every four
seconds would be satisfactory, so about ten minutes
before moonrise I started to key the transmitter, for
thirty minutes with no observable results.
•
After operating for about ten days, it became evident
that the TR system was not working satisfactorily
The TR tubes were not protecting the receiver from
the strong transmitted pulse.
10/7/2010
15
Engineers from the Antenna
Design Section were called in.
• J. Ruze, head of the section, and A. Kampinsky designed a
system using quarter-wave step-up transformers on the
250-ohm line with open spark gaps on the ends of the
quarter-wave TR and ATR.
• But the gaps would not last because of the unusually bang
pulses, although normally they work very well on
conventional radar sets where the pulses are very short and
the average power is low.
• The next step was to design a mechanical TR system using
an electro-mechanical keyer which bars on the transmission
line, the keying being arranged that the shorting bars would
have to be closed before the transmitter would go on.
• But still we did not succeed in getting a response from the
moon.
10/7/2010
16
Part of the solution
• The head of the Research section of the Laboratory, E.
K. Stodola, W3IYF, Dr. Harold Webb and J. Mofensen,
now part of the moon-radar group, decided that:
• If two antennas could be mounted side by side on the
same tower the additional 6 db. gain that, could be
realized in the two-way system would be an
advantage.
• Engineers from the Mechanical Design Section were
consulted. Under the able direction of J. Zorowritz this
rather difficult feat was accomplished.
•
According to the reciprocity theorem, the transmitting and receiving
patterns of an antenna are identical at a given wavelength
10/7/2010
17
Now instead of 32 dipoles we had 64. The phasing
of the dipoles was done by F. Haacke, P. Hartman
and F. Elacker, ex. W2DMD.
• During the time that the new antenna was being
assembled and installed it was decided to utilize the
narrowest band-pass possible in the receiver, to design
an electronic keyer and sweep generator in order to
operate a nine-inch cathode ray oscilloscope, and to
measure the receiver sensitivity.
• Test results found that 0.04 micro volts would equal
the receiver noise, showing that the receiver was many
times more sensitive than our previous ham receivers although it should be noted that the band-width used
(about 50 cycles) is much too narrow for voice
communication (20 to 20,000 Hz)
• At 2.7 m (111 Mhz) wavelength the antenna utilized
ground reflection in order to increase the gain of the
aerial beam, which was fixed at low elevation.
10/7/2010
18
Tentative wiring configuration as per site description. Ing Luis A. Riesco
NOTE: In 1971 the Army destroyed documentation and “Camp Evans history went up in smoke” InfoAge
Evidently a quick draft based on multiple dipoles
amateur radio antennas configuration
To my surprise one panel wired in the same fashion
HIGHER FREQUENCY TECHNIQUES, Page 117
Departments of the Army and Air Force, 1952
•open
10/7/2010
19
Antenna Pattern and Considerations
•
The fundamental characteristics of an antenna are its Gain and the half power
beamwidth (HPBW) angular separation between the half power points on the
antenna radiation pattern, where the gain is one half the maximum value.
•
For this antenna the beam width of the array is approximately 15 deg at the
half power point, with the first three lobes spaced approximately 3 deg in
elevation.
•
9. “The SCR-270 in Japan” page 11 Fig 85, shows the “Expected vertical
coverage diagram” For the 100 Kw Pk Pwr radar with a Westinghouse water
cooled WL-530 tube. The antenna pattern for the “Final experimental version”
was 500 KW Pk Pwr with two air cooled Triodes JAN6C21 using the same
antenna the only difference is the distance in miles. It was concluded that:
Since the diameter of the moon subtends roughly one half degree of arc, most
of the power transmitted does not illuminate the target, a serious waste of
power. The transmitter was driven as hard as possible to get considerably
more power from it, and reach the moon with the first lobe as instructed.
•
The rate of rise of the moon along its ecliptic is 1 degree of arc every 4
minutes, which allowed roughly 40 minutes of observation as the moon
intercepted the first three lobes of the antenna.
•
Bending effects path through the ionosphere exist, but no precise
measurement of this effect has yet been made.
10/7/2010
20
How to reach the moon and detect a back signal
Free space radar equation #1
Basic formula for maximum distance at which a radar set can detect
targets as function of peak transmitter power, radio frequency of the
transmitted signal, duration of the signal, receiver noise figure, and
target echoing area.
These constants, among others, are concisely summarized in the:
Form #1
•r is the radar range at which a signal may be detected,
•Pt is the transmitter power during the pulse,
•Go, the transmitting antenna power gain,
•Ao the absorption area of the receiving antenna,
•o’ the effective echoing area of the target,
•Pr the power of a barely discernible signal,
10/7/2010
21
Theoretical Considerations
•
On the same basis as Pt. The power gain due to ground reflections
(not considered in the free space equation)increases the range of the
system by a factor of 2.
•
This is equivalent to a power gain of 12 db. In the case of a target as
large as the moon (2160 miles diameter), calculations showed that in
order to receive an echo from the whole hemisphere of the moon at
once, a pulse width greater than 0.02 seconds was required.
•
This set a lower limit on the transmitter pulse width which
corresponds to an optimum bandwidth of 50 Hz for the receiver.
•
Propagation studies indicated that electromagnetic waves at a
frequency of 110 Mz were capable of penetrating the ionosphere,
and because of availability of equipment, a radar set operating at
111.5 Mz was chosen for the experiment.
http://radiojove.gsfc.nasa.gov/education/educ/radio/tran-rec/exerc/iono.htm
The effect of Earths Upper Atmosphere on Radio Signal
Atmospheric Windows of EM radiations
10/7/2010
22
Pr Minimum perceptible receiver power #2 and Noise Figure #3
•Due to the relative velocities of the earth and the moon, the returned signal may
differ from the transmitted signal by 300 Hz Doppler frequency shift.
• In using a highly selective receiver whose final mixer is tuned to receive the pre
calculated frequency of an echo return from the moon, the receiver rejects any
signal returned at any other frequency.
•To reduce the noise contribution of the receiver, a high gain, low noise figure
preamplifier was connected between the antenna and the receiver.
•The minimum perceptible received power Pr #2
Form. #2
calculating NF
Form. #3
E2/4R maximum available signal power at the receiver input terminals in watts E is
the signal voltage at the antenna terminals. R is the effective impedance in ohms.
•KTB is the maximum available noise power at the receiver input
K is Boltzman's constant, 1.37 X 10-23 joules per degree Kelvin.
T temperature in degrees Kelvin, chosen, at 300 degrees
B is the noise bandwidth of the receiver in Hz/sec For this receiver B is 57 Hz/sec
10/7/2010
23
Antenna effective gain
•
For a one to one ratio Form # 3 gives signal power to noise power of 1.48 X 10-18
watts, taking the effective noise figure (NF)of the receiver as 7 db.
•
The best antenna available at this frequency was a 32 horizontal dipole array
utilized by the SCR-271 early warning radar.
•
Two of these arrays 64 dipoles were secured side by side and mounted on a
30m (100 ft) tower.
•
Calculations show that the array had now a power gain of 152 times that of a
single half wave dipole antenna.
•
Since the effective gain of a single dipole is 1.64 times that of an isotropic
radiator, the value of G is given as 1.64 X 152 or power gain 250 times a single
half wave dipole
10/7/2010
24
Receiving effective range
•The absorption area A, of the receiving antenna is calculated from
substituting the value of G, previously given, Ao = 522.1 X 10-7 square
miles.
• Substitution of these values in the free space radar equation gave a
maximum range of 573,500 miles
•The effective range of the equipment was more than twice that
needed to receive echoes from the moon.
10/7/2010
25
Efective area of the target #3 Summarizing
•The remaining constant to be determined before solving Eq. 1 is o
•Calculations of the reflectivity coefficient made by Walter McAfee of the
Theoretical Studies Group, assuming zero conductivity and a dielectric constant
of six for the moon, resulted in the figure 0.1766.
•The effective echoing area is this figure multiplied by the projected area of the
moon, Pi d2/4 where d is the lunar diameter. This gave an effective echoing
area of 0.1766 (2160)2 (3.1416)/4 or 647,000 square miles
•r is the radar range at which a signal may be detected…573,500 Mi or 922716 Km
Pt is the transmitter power during the pulse……..30 Kw
•Go, the transmitting antenna power gain……… 250
Ao the absorption area of the receiving antenna…522.1 X 10-7 square miles.
o the effective echoing area of the target……….647,000 square miles
Pr the power of a barely discernible signal……..20 dB above thermal noise
10/7/2010
26
Maximum receiving range considerations
•This calculation of the signal strength of the returned echo checked
closely with observations and indicated that no appreciable
attenuation occurs in free space.
2
•By adding the power gain due to ground reflection, a further excess
of power of 12 db or a range of 1,140,000 mi or1,843,460 Km.
• Which meant that according to calculations, the received signal
should be about 20 db above thermal noise.
10/7/2010
27
When radio wave reaches the ionosphere
•The electric field in the wave forces the electrons in the ionosphere into
oscillation at the same frequency as the radio wave.
•Some of the radio-frequency energy is given up to this resonant oscillation.
The oscillating electrons will then either be lost to recombination or will
re-radiate the original wave energy.
•Total refraction can occur when the collision frequency of the ionosphere is less
than the radio frequency, and if the electron density in the ionosphere is great
enough.
•Critical frequency is the limiting frequency at or below which a radio wave is
reflected by an ionospheric layer at vertical incidence.
•If the transmitted frequency is higher than the plasma frequency of the
ionosphere, then the electrons cannot respond fast enough, and they are not able
to re-radiate the signal. It is calculated as shown below: where N = electron
density per cm3 and fcritical is in MHz.
10/7/2010
28
Frequency and angle considerations
•The Maximum Usable Frequency (muf ) is defined as the upper
frequency limit that can be used for transmission between two points at
a specified time. where α = angle of attack, the angle of the wave
relative to the horizon, and sin is the sine function.
•The cutoff frequency is the frequency below which a radio wave fails
to penetrate a layer of the ionosphere at the incidence angle required
for transmission between two specified points by refraction from the
layer.
10/7/2010
29
Temperature profile a high altitudes
http://chemistry.about.com/library/weekly/bltempconvert.htm
Above 100 km is the thermosphere and ionosphere where the temperature increases from 200 K at 100 km to 500 K at 300 km.
Basically at the bottom it is 200K. At the top it is 500K. K is in Kelvin.
Celsius it would be -73 ºC to 227 ºC. ………………K..Substract –273.15=Centigrade
10/7/2010
Fahrenheit it would be -99.4 ºF to 440.6 ºF…………K
30
Summarizing all calculations
•r is the radar range at which a signal may be detected 573,500 Mi or 922716 Km
Pt is the transmitter power during the pulse……..30 Kw
•Go, the transmitting antenna power gain……… 250
Ao the absorption area of the receiving antenna…522.1 X 10-7 square miles.
o’ the effective echoing area of the target……….647,000 square miles
Pr the power of a barely discernible signal……..20 dB above thermal noise
•http://www.daycounter.com/Calculators/Decibels-Calculator.phtml
10/7/2010
31
The "bedspring" mast antenna
The two antennas from SCR-271
stationary radars were positioned side by
side to form a 64-dipole array aerial,
mounted on a 30m (100-ft) tower.
•Originally RCA design, remarkable for
BW and absence of secondary lobes.
The antenna had only azimuth control
It was impractical an equatorial
mechanism. No prevision has been
made to incline the antenna in elevation.
Hence, experiments were limited to the
rising and setting of the Moon.
“This condition of observation is the
worst possible (due to the long path
through the atmosphere and the
consequent possibility of trapped
radiation) has been recognized”
(Courtesy of the U.S. Army CommunicationsElectronics Museum, Ft. Monmouth, New Jersey.)
10/7/2010
32
The Transmitter, Receiver, Keyer and Indicator
•Transmitter Conventional: At 516.2 KHz x24x9= 111,5 MHz (MC)
•Receiver Non conventional. Designed by Major E. H. Armstrong for another purpose selected, as met the requirements of power and BW.
•All the receiver is frequency controlled, with four mixer stages which heterodyne the radio frequency signal to of 180 cps. T he first three injection
frequency and the final radio frequency are derived from multiples common crystal oscillator, a high degree of frequency stab ility is achieved in the
system essential to permit tuning the highly selective receiver to the frequency of the echo signal accomplished in the final heterodyne stage.
•Keying: A low level multiplier stage conduct by driving its cathode negative for the duration of the transmitted pulse .25 sec on eve ry 4 sec
Initially keying performed mechanically by a relay, but been replaced by an electronic keyer controllable between 0.02 to 0. 2 seconds
10/7/2010
33
Jack Mofenson, adjusts the position on the
transmission line of the waveform monitoring stub
10/7/2010
34
Equipment adjustment
10/7/2010
35
Lt. Col. John H. De Witt at the Power Transmitter Stage.
10/7/2010
36
Triode JAN6C21 Power Transmitter Stage
10/7/2010
37
Year
1946
New Moon
Jan 3 12:30 P
First Quarter
Full Moon
Last Quarter
Jan 10 20:27
Jan 17 14:46
Jan 25 05:00
•http://www.moonconnection.com/moon_phases_calendar.phtml
10/7/2010
38
The first echoes from the moon were received at moonrise on January 10, 1946
•
11:48 A.M. they aimed the antenna at the horizon and began transmitting. The
first signals were detected at 11:58 A.M., and the experiment was concluded at
12:09 P.M., when the Moon moved out of the radar's range.
•
The modified radio receiver was an audible 180 cycle beat note occurring 2.5
seconds after transmission. Although numerous observations have been made,
both at moonrise and moonset, echo returns do not occur after every
transmission.
•
The radio waves had taken about 2.5 seconds to travel from Hearth to the Moon
and back, a distance of over 800,000 km.
•
Camp Evans Audio, scroll down to “Project Diana - Radar Makes Round Trip to the Moon”
http://njarcsite.sicaproductions.com/streaming/
10/7/2010
39
Sociology in Diana Experiment 2
•History on High officer to Subordinate relationship shows some cases that low level military in some
countries are not authorize to give directives to superior officers.
•Pearl Harbor wrong data interpretation and faliure to verification shows:
•The first wave of Japanese planes numbered more than 180. Although U.S. radar operators saw the
massive formation nearly a full hour before the attack began, they raised no alarm, because they mistook
the planes for a group of U.S. bombers expected to arrive from California around the same time.
•This mistake happened in spite of the fact that the planes seen on the radar were coming from the wrong
direction and were much more numerous than the expected bomber fleet.
•De Witt developed a team work in a Management by Design Objective environment.
•Motivated his staff. In some cases they made test run experimentation with not failure report.
•However he always was in control of the project. His instructions shows that driving hard the
equipment was able to considerably exceed the return radar pulse requirements. Calculations and
measurement trusted and verified. The signal transmission and moon eco reception met the project
objectives. After celebration, pictures, films and PR activity the team work continue until,
•Some time later the Army, concluded however, that nothing of military use would come of this work
and ended the experiments.
•At the Naval Research Laboratory, Mr. James H. Trexler saw that the moon reflections might be useful
in relaying military communications and got his project funded.
10/7/2010
40
Lt. Col. De Witt’s Experiment were of great influence on the later
development of Earth Moon Earth (EME) communications
•
Mr. Trexler's idea for a communications relay capability using the moon
Project Pamor (Passive Moon Relay) was funded by the Naval Security Group.
•
With NAVSECGRU funding, Trexler's development teams built a 60-foot-diameter
antenna (actually a reflector-shaped hole in the ground), at Stump Neck, Maryland, and
with NRL in-house funding proceeded to experiment with T&R of signals off the moon.
•
1951- The feasibility study of using moon reflections communications was successful
•
1954- On July 25th, using a 100-watt 220-megahertz communications transmitter, NRL
transmitted the first voice messages via the EME path.
•
1955- On November Transcontinental communications were demonstrated teletyping
messages from Washington DC to San Diego; two months later NRL conducted
transoceanic communications EME between Washington DC and Hawaii.
•
1956-The Chief of Naval Operations directed the establishment of the Communication
Moon Relay (CMR) system for transmission of teletype and facsimile messages between
Washington DC and Hawaii. Using 84-foot-diameter dish antennas-one for transmitting,
the other for receiving.
•
•
•
Transmitter at the U.S. Naval Radio Station, Annapolis, Maryland,
Receiver at Cheltenham, Maryland.
The Hawaiian facilities at Opana and Wahiawa on the island of Oahu.
10/7/2010
41
Test results verification and predictions
•1946 January 10th –The experiment was daily repeated three days and eight days by the end of the
month.
•1946 January 24-Until then The War Department withheld announcement of the success.
A press
release explained:
•"The Signal Corps was certain beyond doubt that the experiment was successful and that the
results achieved were pain-stakingly [sic] verified."
•As DeWitt recounted years later: "We had trouble with General Van Deusen our head of R&D in
Washington. When my C.O. Col. Victor Conrad told him about it over the telephone the General did
not want the story released until it was confirmed by outsiders for fear it would embarrass the Sig[nal].
C[orps].“
• Two outsiders from the Radiation Laboratory, George E. Valley, Jr. and Donald G. Fink, arrived and,
with Gen. Van Deusen, observed a moonrise test of the system carried out under the direction of King
Stodola. Nothing happened. DeWitt explained: "You can imagine that at this point I was dying. Shortly
a big truck passed by on the road next to the equipment and immediately the echoes popped up.
• I will always believe that one of the crystals was not oscillating until it was shaken up or there was a
•Several years later, the Signal Corps erected a new 50-ft (15 meters) Diana antenna 108-MHz
loose connection which fixed itself. Everyone cheered except the General who tried to look pleased."
transmitter for ionospheric research, lunar echo studies and the tracking of the Apollo launches.
• The implications of the Signal Corps experiment were grasped by the War Department, although
Newsweek cynically cast doubt on the War Department's predictions by calling them worthy of Jules
Verne.
•Time reported that Diana might provide a test of Albert Einstein's Theory of Relativity. In contrast to
the typically up-beat mood of Life, both magazines were skeptical, and rightly so; yet all of the
predictions made by the War Department, including the relativity test, have come true in the manner
10/7/2010
•END
PART
2
of a Jules
Verne novel.
42