Moon Col-R-Tel used its fields in a different way than
Earth TV did. Moon video painted a color picture in six
fields. But Earth TV painted that color picture in only two
fields. For this reason, video coming from the Moon required
conversion before we could view it.
Video 101.We need to define a few terms: A
frame is one picture in a series that
appears as moving video. Earth televison systems built each
video frame from two fields. A field was half of a
video frame. Each field contained alternate scan
lines: Odd lines in one field. Even lines in the other.
The scan lines ran left to right, and drew the picture on
the screen. Back to the two video fields. Over time, two
fields meshed, reducing flicker effects for the viewer.
Moon vs. Earth Col-R-Tel. The Moon color
system was Earth Col-R-Tel in reverse. Recall that Earth Col-R-Tel
transformed NTSC television signals into field-sequential signals. Video from
the Moon was another matter. It was already field-sequential. The Earth
downlink station translated this video to NTSC.
Standard TV sets could reproduce the downlink station's output.
Downlink adapters made viewable pictures for home sets across the world. Now
let's take a deeper look at the video arriving from the Moon.
The mooncam process complemented downlink station processes: The mooncam selected one of
three colors per field and transmitted that color to the downlink station. Filters in the color
wheel caused the camera to ignore or skip the other two colors. Skipping colors reduced the
video bandwidth. Due to color-skipping, each color in a mooncam video only updated once per every
three video fields. (Wetmore 20) Note: The output of an Earth Col-R-Tel adapter followed the same,
lossy mooncam process.
WEC Mooncam for lunar surface, color (Wood 29)
Color sensor. RCA's GCTA camera transmitted a “field complete”
signal. The camera relayed this signal during the horizontal interval of line 18. Before
every green field, a phototransistor picked up a lamp shining through an aperture in the color
wheel. There were two such apertures in the wheel. For this reason, every time the wheel
revolved, the phototransistor pulsed its signal twice. (RCA 1-12, 1-20, 1-28, 1-29, 1-30,
1-35, & 1-36) The downlink station could use the “field complete” signal as
a reference. This reference allowed the downlink to route the correct signal to each
input of the color matrix and proc amp.
The WEC camera used a magnet and coil to detect a similar signal. (Apollo Color
Television Subsystem Operation and Training Manual 3-9)
(R= Red; B= Blue; G= Green)
Moon Frame 1
Moon Frame 2
Moon Frame 3
Field 1: R (Odd)
Field 2: B (Even)
Field 3: G (Odd)
Field 4: R (Even)
Field 5: B (Odd)
Field 6: G (Even)
Skip B (Odd)
Skip G (Even)
Skip R (Odd)
Skip B (Even)
Skip G (Odd)
Skip R (Even)
Skip G (Odd)
Skip R (Even)
Skip B (Odd)
Skip G (Even)
Skip R (Odd)
Skip B (Even)
Transmit R (Odd)
Transmit B (Even)
Transmit G (Odd)
Transmit R (Even)
Transmit B (Odd)
Transmit G (Even)
Making data is tougher than discarding data. Just so,
converting Moon Col-R-Tel to NTSC was more difficult than conversion going
the other way. While Earth Col-R-Tel worked by losing color data,
Moon Col-R-Tel (the downlink) worked by making color data.
That is, Earth Col-R-Tel discarded two colors per NTSC video field. At
the downlink station, Moon Col-R-Tel borrowed data from adjacent
frames, and actually built new frames. The field-sequential to NTSC
color conversion equipment was a form of mechanical television.
Time Delays. The downlink conversion process occurred during Moon
telecasts, but delayed the output video. (Spacecraft Films, “TV Transmission
33:59 GET”) The Doppler correction alone caused about a 12-second delay.
This delay resulted from a tape loop between machines. (Wetmore 20) Additional delays
occurred during transmission from downlink stations to synchronous satellites in Earth
orbit. Such transmissions occurred between downlink stations and NASA-Houston, and
between NASA and other countries. In Europe and Asia, coaxial cable
and TV standard conversion caused further delays.
Compensating for Doppler Shift
Doppler shift. Before the downlink station could begin its conversion, it
had to correct for Doppler shift in the Moon signal. The shift varied depending on
the relative motion of the Earth and the spacecraft. Standard TV sync circuits
couldn't reliably lock a Doppler-shifted picture. Without Doppler shift
correction, the pictures would tear and flip. The correction process was
partly mechanical and partly electronic.
Video Backup. Before sending the Mooncam signals to Houston, downlink stations in California,
Spain, and Australia made backup copies of the signals. For the local backups, the downlinks used Ampex
VR-660B, video tape recorders. These were early helical VTRs for monochrome signals, not color.
Yet because a mooncam didn't send a chroma signal, a monochrome recorder could still capture pictures in
color! The VTRs used two-inch tape on reels. (Wood 11, 12)
Normal (top) vs. Doppler-shifted (bottom) horizontal sync. Bottom-left:
Departing spacecraft stretches sync & picture. Bottom-right: Approaching spacecraft squeezes sync & picture.
(Adaptation from Grob 68)
Two Machines. Houston corrected the signals for Doppler shift. NASA used two, quadruplex,
2-inch videotape machines. One machine recorded. We'll call this machine the recorder. The other
machine played back. We'll call this machine the player. (Wood, 7) The two machines operated as an
electromechanical time base corrector.
Tape from the recorder ran to the player. Between the recorder and player, the tape was nearly slack.
This slackness allowed one machine to operate faster than the other without breaking the tape. There was another
complication: Normally when tape tension slackens, a tape sensor shuts down a tape machine. The answer to this
problem was a counterweight between the players. The counterweight maintained just enough tape tension. This
constant tension kept the tape sensors from stopping either machine. (Wetmore, 20)
Doppler corrector, field storage unit and NTSC encoder. (The “Color
Converter” was a video disc recorder.) Source: Apollo
Color Television Subsystem Operation and Training Manual 5-2.
The recorder taped the TV signal from the spacecraft. This TV signal included sync pulses
that stabilized the picture. On the tape, the time between recorded sync pulses varied. This
time depended on the direction of spacecraft motion with respect to Earth: When the spacecraft
receded, intervals between sync pulses grew longer. When the spacecraft approached, the
intervals grew shorter. On the Moon, heating and cooling of the sync generator circuits
caused more phase shifts. (Wood 12)
Servo. A crystal-controlled servo drove the player. This servo locked on the NTSC color subcarrier
frequency, 3.58 MHz. The servo’s other input was the taped horizontal sync pulses from the
recorder. Normally, these horizontal sync pulses followed the NTSC standard and occurred at 15,734 Hz. The
crystal frequency and the normal sync frequency had a common quotient of 7,867 Hz: The servo divided
the crystal frequency by 455 to produce a 7,867-Hz signal. The servo also divided the horizontal
frequency by two. Normally this operation would also produce 7,867 Hz. Yet due to Doppler
shift, the result might be off by several Hz.
Subcarrier quotient. As its standard, the servo used the crystal subcarrier quotient
(7,867 Hz). The servo compared the two quotient frequencies. Any difference between these two
frequencies caused a correction voltage. The servo used this correction voltage to
vary the player speed. The varying player speed corrected for differing intervals between sync pulses.
Output sync matched the NTSC standard. The player's video output ran to the scan converter.
Conversion from Field-Sequential to NTSC
Downlink station color conversion. Time for a little review. On the Moon,
cameras scanned one color video field at a time. After six color fields, a full
color frame resulted. This was field-sequential scanning. On Earth, color TV sets
scanned all three colors simultaneously. Every Earth field contained three colors.
Two Earth fields made up a frame. The three primary colors arrived at an Earth
receiver over a chroma signal. Chroma was separate from the
monochrome (luminance) signal. The Earth set combined chroma and luminance
and voilà: Color TV! But the mooncam didn't provide chroma. Instead, the
mooncam mixed color and monochrome data. And that's why NASA needed a
downlink converter. The downlink station had to convert the Moon video
to Earth video. The conversion process repeated each Moon color field three
times, as part of three Earth fields. (Repeats began after the first two
Distributing data. Despite the data duplication, the downlink
equipment never invented new picture elements. Instead of dreaming up
the missing data, the process involved distributing received data. For
example, Moon fields 1-2-3 became Earth Field 1. Moon fields 2-3-4 became
Earth Field 2. Moon fields 3-4-5 became Earth Field 3. Westinghouse called
this field-combination method the moving window. The moving window
preserved the natural flow of motion over time.
Sheared frames. The downlink process also sheared a half line from the top
many Moon fields. Other downlink circuitry added normal luminance, chrominance,
burst, and sound to the Moon signal.
The “moving window” combined Moon video fields to
assemble Earth video fields. Each Moon field repeated three times.
The downlink picture conversion process was analog. The idea was
to record Moon fields serially and play them back in parallel.
To store, repeat and combine Moon video fields, the Apollo missions used
magnetic disc recorders. Ampex developed this type of recorder for use
in sporting events. Starting in 1967, such recorders made possible the
instant replays that football fans love. (Abramson, 117-118) Westinghouse
modified Ampex HS-100 recorders for use in NASA downlink stations.
The stock HS-100 recorder had two discs, and recorded on both sides
of each one. This recorder contained 1,800 tracks (450 tracks for
per side, times two discs). Each track could record one video field.
Alternate fields recorded on alternate disc sides. The HS-100 disc
rotated at 3,600 rpm. In one rotation, each side of each disc could
record or play back one video field. The next video field would record
on the next side. There were four record-play-erase heads, one for each
side of the two discs. The four heads could be active at once, with each
head operating on a separate track. (Ennes, 485, 488-489)
Stock Ampex HS-100 disc recorder included 2 discs. Had one record-playback-erase
head per disc side. Video fields alternated between disk sides: Field 1 on Disc 1,
top. Field 2 on Disc 1, bottom, etc. (Adaptation from Dunlop 111.)
Probable Modification. Downlink operations required six tracks.
(Specifications called for activity on five tracks, with the sixth track
remaining unchanged.) The need for six tracks (five active at
once) would have been beyond the HS-100's capacity. With four heads, the
stock machine could only support four active tracks. Likely Westinghouse
satisfied its requirements by adding a third disc and two more heads to the
recorder. (Or maybe Westinghouse used two disc recorders.)
Right: Likely 3-disc modification of Ampex HS-100. NASA required
6 tracks & 5 simultaneous operations. These goals would require 6
heads A-F. Custom 3-disc, 6-head recorder would have satisfied
Disc operations. The recorder performed a different task on each track.
On each successive disc rotation, this task switched by one operation. Playback
(read) tasks occurred simultaneously and built the output video field. Each
output field included two matching Moon fields and one that didn't match. For
example, one even and two odd fields, or two even and one odd Moon fields. Normal
field interlacing caused this mismatch. (Source of the mismatch: Standard odd
fields began scanning at the top-left corner of the screen. Even fields began
scanning a half line away, at the top-middle of the screen.)
The disc recorder corrected the mismatch by introducing a brief delay. A
half-line delay before starting the record head sheared off half a line. After
the delay, the resulting Moon field matched the other two Moon fields. Leaving
the non-matching field as-is would start scanning at the wrong screen location. A
delay line in the disc recorder achieved the shearing effect. (Ennes 493, 495)
The delay line was a passive, analog device of the quartz (not RCL) type.
The delay before scanning was 31.5 microseconds. (Wood, 6)
Right: Two interlaced fields made up each video frame.
First field, odd lines. Second field, even lines. Each
field started on different part of screen. Downlink station had
to convert every third field from even to odd, or odd to even.
Conversion involved shearing off half of first line.
Video disc operation. The “Loading Moon Fields” tables below describe
operation of the video disc.
These tables derive from page 5-4, Figure 27 of this book: Apollo Color Television
Subsystem Operation and Training Manual (by Westinghouse, or “WEC”). Each
new disc rotation began immediately at the end of the previous rotation. (After Disc
Rotation 6, the process at Disc Rotation 1 repeated, only with new data.) There was no
time for heads to move radially. That is, “between disc rotations,” the
six heads remained stationary. This mode of operation differed markedly from
typical operation. Ennes (490) describes typical operation: One or more heads would step
to a new track while another head recorded.
Error in Record-Playback Sequence. This page corrects an error in
the manual's disc color sequence. The book gave the sequence as R-G-B (red-green-blue).
A private email from the late Stanley Lebar clearly and emphatically states that the
sequence was R-B-G. The basis of this sequence was the color wheel that revolved before
the Moon camera lens. This wheel adhered to Peter Goldmark's original CBS specifications.
Not surprisingly, the Col-R-Tel scanning disc also followed Goldmark's R-B-G scanning
RCA camera. According to the RCA camera manual, the RCA camera also followed the
R-B-G sequence. (RCA 1-12) This sequence is why the same downlink equipment and program
would work for both the WEC and RCA cameras.
There was no way to specify which color field was the “first one” to
come from the Moon. (Those who wish to view the R-G-B order from the WEC manual may use
the color-change buttons. These buttons are beneath each table below.)
First usable field. The disc had to contain three stored Moon fields. Otherwise,
the disc couldn't play back enough data for one Earth field. The first four disc rotations
recorded Moon fields into tracks 6, 1, 2, and 3. But what the disc played back was incomplete,
and no usable Earth field resulted. Usable Earth fields didn't emerge from the system until
Rotation 5. Each rotation took 16.7 milliseconds, so Rotation 5 wasn't complete until
the 83-millisecond point. For that reason, there was a fleeting delay before the system
could process the first Earth field.
The R-B-G colors for each track are examples from Westinghouse. (Apollo
Color Television Subsystem Operation and Training Manual, Figure 27, 5-4.) For instance,
in the first table: “Track 1: Red-Even.”
At Houston, the mooncam video underwent various electronic processes. The parallel
output from the disc recorder fed to a standard color matrix (multiplexer)
circuit. Next after the matrix came a proc (processing) amplifier. (Wetmore 20)
NASA used stock equipment, probably by Grass Valley Group. (Wood 11) The matrix had three
inputs, one for each color field signal. The matrix output standard NTSC signals. (Apollo
Color Television Subsystem Operation and Training Manual 5-5, 5-6) These signals
A luminance signal (merged RBG fields)
In-phase-I and quadrature-Q, amplitude-modulated (QAM),
suppressed carrier chroma. The I and Q signals defined the hue
(phase)and saturation (intensity) for each
primary color in the picture. The chroma bandwidth was
one-eighth as detailed as the luminance
The color burst signal, during horizontal blanking.
Phasor diagram: Chroma signals, NTSC (US, Mexico, Canada,
Japan, etc.) and PAL TV (Australia, most of Europe, etc.)
The proc amp provided...
New, stable horizontal and vertical sync
Stronger chroma signals (if necessary)
The sound subcarrier, mixing Moon and Earth chatter.
During transmission worldwide via satellite, each country converted the NTSC
(U.S.) TV signals to the local format.
Fringe “Benefit.” Apollo Moon pictures often had color fringes. Such
fringes are a flaw of field-sequential scanning. Fringes resulted from unmatched content
within neighboring Moon video fields. See photo, right. A mismatch would occur anytime
an astronaut moved quickly. The color fringes persisted even after conversion to
simultaneous color television (NTSC/PAL/SECAM).
What Viewers Saw. During motion sequences, such as an astronaut waving his arm,
viewers noticed colored “trails.” For example, a moving arm would leave a
momentary trail of arms: A red, a blue, and a green arm. A moment later, the “arms”
would merge again, and appear as a single arm of natural color.
Right: Click picture to watch video of color fringes.
(NASA video: Charlie Duke, during Moon surface EVA, Apollo 16.
Earth Col-R-Tel TVs could have picked up
Moon Col-R-Tel pictures. This reception method would require no
NTSC conversion. Consider that downlink stations included Conrac
studio monitors that engineers had modified for field-sequential
operation. These Col-R-Tel-like monitors could directly receive the
Moon, field-sequential telecast. (Wood 11)
Converters cancel. The Col-R-Tel converter and moon-downlink
converter canceled each other. Thus without NTSC in between the converters,
neither converter would be necessary. The TV pictures would probably come in
Experiment. Someone could prove my statement about Col-R-Tel Moon pictures. The
experiment involves transmitting Moon pictures on a standard TV carrier. Then
the experimenter would reproduce the unconverted Moon signal. The picture
would appear on a Col-R-Tel unit without hue and saturation conversion
electronics. Both the Moon and Earth units would maintain their
Cliff Benham has now performed this experiment, and it works! Cliff's homemade
mooncam has reproduced color TV pictures on an original Col-R-Tel set. Since the camera
pictures were field sequential, the Col-R-Tel converter worked barefoot! That is,
without the adapter electronics. See... Homemade mooncam.
Comparison. Below is a comparison of the Moon and Earth
color standards vs. the CBS color standard. You can see how close
Earth Col-R-Tel signals were to Moon Col-R-Tel signals. Note that
both signals used the same vertical and horizontal frequencies. In both
cases, the CBS system differed. This critical comparison underscores
the statement that...
The CBS system didn't go to the Moon.
The CBS system couldn't lock a Moon TV signal.
Incidentally, this statement applies both before and after the
downlink conversion. Either way, the CBS system was incompatible with
Apollo color Moon pictures. On the other hand, Col-R-Tel borrowed extensively
from both the CBS and NTSC color systems.
Simpler Conversion. If Stanley Lebar had chosen a two-color system, he could have avoided using the disc-based
converter. Two-color, field-sequential pictures transmit at the same frequency as normal NTSC does. That is, 30 frames
per second. In terms of speed, this rate is a huge improvement over the three-color, field-sequential system that Apollo
actually used. Recall that the three-color pictures transmitted at only 10 frames per second.
Still not live. Addition of NTSC signals such as the monochrome signal, chroma, and burst would still occur at the
downlink. Also, Doppler correction would still be a requirement. Doppler correction involves a slight tape delay between
two video recorders. This delay would remain. Yet two-color pictures could have been slightly closer to “live.”
Why go with three colors, then? Because by Newtonian theory, a three-color system has a broader gamut than does
a two-color system. That is, the three-color system can display pictures with more colors and better color fidelity. By
the way, Edwin Land would contest this statement. (Land, Experiments; Retinex) About the same time as the color Apollo flights,
the Spectrac® TV color converter reinforced Land's point. (Benrey 45-47)
1971 Spectrac prototype, showing 2-color conver-sion. (Adaptation from Benrey 45)
Resolution. Another disadvantage of the two-color system is that frames transmit at half resolution. There is no
odd and even field for each color. Instead, for each color, only one field transmits. As with Spectrac, probably nobody
would notice the difference. (Topping patent 1967)
Which 2 colors? A typical two-color system displays orange and teal fields. A
standard CRT makes the orange by turning on its red and green guns. To get teal, the CRT activates its blue and green
guns. The result is much like the standard, NTSC chrominance I-signal. RCA engineers invented the I-signal because it is in
the optimum color range for accurate flesh tones. The eye is more sensitive to flesh tones than to any other color.
Two-Color Mode. Early color TVs included a two-color mode using the high frequencies of the I-signal. Today, few if
any TV sets can decode this mode. (Color Television: Simplified Theory 44-45)
One challenge for a two-color mooncam would be the U.S. flags that Apollo astronauts planted on the moon.
Reproducing the white stripes and stars would be easy for such a two-color camera: Adding 100 percent orange
and 100 percent teal produces white. But the camera's orange and teal axis is far away from either red or blue. What
the camera would record would instead be dark red-orange and dark teal. From a reasonable distance, these colors
would be fairly good stand-ins for red and blue. Take a look at our two-color flag (above). What do you think?
The History of Television: 1942 to 1985. Jefferson, North Carolina: McFarland & Company,
Ampex. “HS-100 Highband,
Slow Motion VTR” Redwood City, California: Ampex Corporation, 1967. Press release including
photos, 8 pp. Contacts: Gregg Perry (Redwood City), John B. Hatch (New York), & Carter G. Elliott
Apollo TV and Communications Documentation: Mooncam
articles, press releases, manuals, plans, etc.
Basic Television: Principles and Servicing. 4th ed. New York: McGraw-HillBook Company, 1975.
Excellent, readable summary of NTSC (analog) television theory. Well-organized, topical chapters and
a thoughtful index make data easy to find. One of the top television textbooks by one of the top television
Johnson, NASA. “Astronaut Charles Duke During an
Apollo 16 Lunar Surface EVA” YouTube Video, 1:16. August 1, 2011. Accessed this site on July 29, 2019.
Provides a good example of the spurious color fringes that are an artifact of field-sequential scanning. Watch
for the fringes whenever Astronaut Charlie Duke swings the hammer or makes a sudden move.
Lebar, Stanley. “The Color War Goes to the
Moon.”Invention and technology (Summer, 1997): 52 and 54.
Stanley Lebar's story of the Westinghouse cameras. The late Mr. Lebar was Westinghouse's program manager for the
mooncam project. Includes a photo of the color wheel. The layout of this wheel followed the layout of Peter
Goldmark's color wheels for CBS. As on Goldmark's discs, color wedges curved away from the direction of
disc travel. The curve of the wedges indicated the color sequence: Red—blue—green.
Lebar, Stanley. Private correspondence about Westinghouse's Apollo TV color cameras, emphasizing
color scanning order, 11-23 through 25-2006.
Lebar, Stanley. Private correspondence about Westinghouse and its development of color TV
cameras for the Apollo Moon program, 2009.
Lindsay, Hamish. “A Technical Description
of Honeysuckle Creek During the Apollo Era.”; https://www.honeysucklecreek.net/. Accessed this site on June 24,
2019. URL: https://www.honeysucklecreek.net/station/technical.html
Subject: Downlink station equipment and operations in Australia, primarily Honeysuckle Creek, but also Tidbinbilla &
Parkes. Site includes link to brief video of Stanley Lebar. Stan introduces Apollo monochrome & color mooncams &
on-board video monitor.
Luckett, Hubert. “For $150 and a Bit of Work You Can Have Color Pictures on Your Present Television Set.”
Popular Science, October 1955. Color pictures from a black-and-white television: Description of the Col-R-Tel kit by
Color Converter, Inc. How to install it and set it up. The Col-R-Tel converter was a CBS-like color wheel and drive that
operated off the TV's vertical sync. The Col-R-Tel adapter was an electronic circuit. Like the mooncams, this circuit was
Spartan technology: Only the essentials. By discarding information, the adapter derived field sequential color from incoming
simultaneous color signals. This clever circuit only required one chroma demodulator, and no delay line. The converted
set required no convergence adjustments. Col-R-Tel was only for NTSC sets.
Niemyer, L.L., Jr., “Apollo Color Television
Camera,” media release, Westinghouse Defense and Space Center, Aerospace Division, Baltimore, MD, September
16, 1969. Presentation detailing the Apollo color cameras by a prominent WEC engineer. Mr. Niemyer delivered this white
paper at the Electo-Optical Systems Design Conference in New York.
Russell, Sam. “Shooting the
Apollo Moonwalks: A Recollection of How It Was Done.”
http://www.hq.nasa.gov/alsj/Shooting-Moonwalks.pdf Access on June 13, 2019. The late Mr. Russell was the RCA
Project Engineer. Covers Apollo 15-16-17 cameras.
Spacecraft Films. “TV Transmission 33:59 GET.”Apollo 11: Men on the Moon. DVD set. No director. Los Angeles:
20th Century Fox, 2003. Specifies 12-second delay during downlink processing of color video from command module
color TV camera.
Spacecraft Films. “Probe & Drogue TV.”Apollo 11: Men on the Moon. DVD set. No director. Los Angeles:
20th Century Fox, 2003. Mentions 12-second delay during downlink conversion of field-sequential color video from command module
Topping, F.V. Color Converter for Black and
White Television Sets. U.S. patent 3,535,435, filed May 22, 1967, and issued October 20, 1970. Topping's "Spectrac" system
produces splendid, naturalistic color pictures on a black-and-white TV. With the assembled Spectrac kit, a two-color
(red and cyan) filter fit over the TV screen. Viewers watched TV through a slow-moving, two-level, striped belt.
The belt alternately obscured red or cyan stripes. The stripes were extremely narrow. They had the effect of turning
the entire screen either red or cyan. Spectrac electronics sequentially switched the video: Only red video
appeared when the screen was red. Conversely, only cyan video appeared when the screen was cyan. (By red or cyan video, we
refer to intensity values for each color. That is, Spectrac combined saturation and brightness for each color, deriving
intensity.) At normal viewing distances, neither the moving nor the stationary stripes were visible. The only
artifact of the coloring process was a slight flicker in the picture. A display of the system enthralled vistors to the
Chicago Consumer Electronic Show in 1971. A later Popular Science article described the system in detail, with
technical drawings. Unfortunately Topping couldn't obtain adequate funding for manufacturing. He abandoned the Spectrac
Westinghouse Defense and Space Center.
“Westinghouse Builds Color TV Camera and 'Mini' Monitor for Apollo 10,” media release, Pittsburgh, PA, May 16,
1969. Quoting Westinghouse engineer Larkin L. Niemyer, Jr. (p. 3): “The wheel spins at 600 revolutions per
minute and is divided into six sections so that the sequence of color filters as they pass in front of the tube
during one revolution will be red, blue and green, red, blue and green.”
Westinghouse Electric Corporation. "Westinghouse TV Cameras
Bring Apollo Video from Liftoff to Moon Landscape," media release, Pittsburgh, PA, n.d. (Probably 1970.) See
p. 11: Details the R-B-G (red-blue-green)
sequence of colors on the Westinghouse color wheel: “As each color filter passes in front of the imaging
tube, it collects all of the information on red colors and hues, then blue colors and green and then repeats
the sequence again.”
Wetmore, Warren C. “First Color TV from
Space.”Aviation Week and Space Technology (May 26, 1969): 18-20. Concerns Apollo 10, the first
mission with a color TV camera. Mentions the R-B-G sequence of colors on the Westinghouse mooncam's color
wheel. Also brings up the counterweight that maintains tape tension in the tape loop between VTRs.
Williamson-Labs. “The-Color Wheel-Camera:
I B M-&-Sarkis Zartarian's-‘Com-Club.’” Williamson Labs. www.williamson-labs.com/480_hal.htm (retrieved 5-23-2013).
Color wheel similarity: Compares Apollo & IBM color wheels. The article mistakenly names
the Apollo color filters as cyan, yellow and magenta (CYM). These are the complements of the true colors. As Stanley Lebar and Cliff Benham
explained to the author: In some photos, the Apollo filters appear to be CYM. This is because the filters are dichroic
filters. Dichroic filters reflect the non-absorbed colors. The strongest rejected colors are the complements CYM.
Wood, Bill. “Apollo Television.”;
www.hq.nasa.gov/alsj. Accessed this site on June 10, 2019. URL: https://www.hq.nasa.gov/alsj/ApolloTV-Acrobat5.pdf
Publication date: 2005. Impeccable detail on both cameras and the downlink station. Includes facts and insights that
don't appear elsewhere. By a former Apollo station engineer on the MSFN (Manned Space Flight Network).
Colin Mackellar, ed. “Honeysuckle Creek TV—Gene Cernan at
Shorty Crater” https://vimeo.com. Accessed this site on June 30, 2019. URL: ttps://vimeo.com/55766658
Publication date: December 17, 2012
Monochrome, 8mm movie off Conrac monitor. Engineers converted this monitor to display
field-sequential color video from the Moon (apparently after Doppler correction). The movie shows flicker from
the roriginal Moon transmission. One can also hear the Super-8 film advancing in the camera. At the Honeysuckle
Creek downlink station, Ed von Renouard shot the original Super-8 film with a home movie camera. Colin Mackellar
added the sound and painstakingly synchronized it to von Renouard's silent footage. The film documents Cernan's
Apollo 17 moonwalk in December 1972.
O'Neill, James E.
“Equipping Apollo For Color Television.” TV Technology Newsletter. Accessed this site on June 10, 2019.
Only site with data on CBS input on downlink station development.