HSGEM – The Hughes GeoMobile Satellite System Story—Andy Ott

In the early 1990’s, Hughes Space and Communications Group (HSCG) teamed with Hughes Network Systems (HNS) to develop a satellite based cellular communications system.  This was to be a total end-to-end system. HSCG was responsible for the Space Segment (spacecraft, spacecraft on-orbit as well as launch operations, including the facilities, software for both spacecraft bus and payload, and launch vehicle procurement). HNS was responsible for the user and ground segments (ground hardware infrastructure, network management, gateway stations, as well as cell phones and the billing system). Project management, including overall “Big-S” Systems Engineering, was the responsibility of HSCG as the prime, requiring formation of a GeoMobile Business Unit within HSCG.

The spacecraft did not fit into either the existing HS601 product line nor the under development at the time HS701 product line, necessitating a unique spacecraft, labeled HSGEM. There were many new, unique requirements for HSGEM space segment, the following is a list of a few of the major challenges:

  1. 13 KW Spacecraft Bus with dry weight 5,500 – 7,000 lbs. A modular Xenon Ion Propulsion System (XIPS) addition, if required due to launch vehicle selection. Payload weight 3500 – 4000 lbs.
  2. A single L-Band 12.25-meter aperture antenna to provide both transmit and receive communications. The Astromesh reflector is 18 ft in length by 44 inches in diameter stowed for launch and when fully deployed is a 52.5 ft by 40 ft ellipse with a 12 ft depth. A 128-element feed array provides in excess of 200 individually controllable spot beams.
  3. Elimination of potential Passive Intermodulation Products (PIM) sources for the spacecraft bus and payload. The diplexer was a special challenge due to the single antenna and the significant difference between receive and transmit power at L-band.
  4. Digital Signal Processor (DSP) to provide channelization, routing and beamforming; all functions previously performed by analog and passive hardware. The DSP included a mobile-to-mobile switch to allow for direct routing of mobile terminal to mobile terminal calls, thereby reducing round trip delay to a single hop. The DSP utilized state of the art at the time ASICs jointly designed and qualified by Hughes and IBM and manufactured by IBM. Flexible digital beamforming was a special challenge.
  5. Common software for payload, spacecraft system test and launch plus on-orbit operations integrated from Commercial, off the shelf (COTS) products and HSCG developed DSP command and control.
  6. Unique approach to North-South station keeping using the power of the payload to perform electronic beam steering vs chemical station keeping while operating in inclined orbit.

A development vehicle and the first two spacecraft were manufactured by HSCG, the Satellite Control Center by Raytheon and the Network Control Center and ground infrastructure by HNS.  The first launch of a HSGEM spacecraft, however, occurred in the year 2000 after HSCG was bought by Boeing. Although Boeing activities are not discussed on this website, it is public information that the first HSGEM was successfully launched by Sea Launch and met or exceeded all requirements (space and ground), resulting in a very successful and happy customer. The satellite and ground systems are still operational today (2018) and revenue creating, exceeding the 12-year life requirement of the contract.

Fig I: HSGEM spacecraft in launch configuration at HSCG High BayFig 2: HSGEM On-orbit

Key to the commercial success of this project was its efficient use of very valuable and much in-demand L-Band frequency spectrum. Ability to control more than 200 individual spot beams allowed for reuse of the same frequency spectrum more than 40 times and tailoring the coverage area to meet needs of specific customers. A comprehensive article, “The Hughes Geo-Mobile Satellite System”, was co-authored by HSCG (John Alexovich and Larry Watson) and HNS (Anthony Noerpel and Dave Roos) with major support from the rest of the “Big S” Systems Team and presented at the 1997 International Mobile Satellite Conference held in Pasadena California. The article is an excellent description of the end-to end system. Some of the key points are as follows (full article appears immediately following key points).:

  1. HSGEM is sized to provide 16,000 voice circuits for 2 million subscribers, including presence of up to 10 dB of shadowing.
  2. The maximum coverage area with over 200 beams, each approximately 0.7 degrees in diameter or 450 km across, is 12 degrees as viewed from geosynchronous altitude.
  3. Dual mode terminals provide the ability to communicate with either the HSGEM or with local terrestrial cellular systems (GSM) for voice, data, facsimile, and supplementary services.
  4. The HSGEM accommodates many features that support flexibility and reconfigurability as technology further advances, which has been demonstrated over 17 years (so far).

 

ATS Mobile Terminals—the Pope Paul VI’s Visit to Columbia, the 2500th Anniversary of the Persian Empire and President Nixon’s Visit to China—Roland Boucher

This Hughes mobile satellite ground station was designed and built in 30 days to transmit live color television coverage of Pope Paul VI’s visit to the Eucharistic Congress in Bogota, Columbia in 1968.

The Go-Ahead

In the spring of 1968 Hughes was asked if it were possible to broadcast, through a satellite, the upcoming visit of Pope Paul VI to Bogota, Columbia. The Early Bird satellites operated by Comsat were considered but they required an 85-foot ground antenna.  Time and cost precluded this approach.  We were about to say NO then I suggested to the group that ATS-3 with is high gain receiving antenna could be used allowing a much smaller 15-foot diameter antenna.  The Hughes Ground Systems Group had just completed a prototype 10,000-watt transmitter.  If it could be made available we had a chance.  I also suggested that the terminal contain a VHF communication set in case the telephone service from Bogota to Hughes California prove unsuitable.  NASA agreed to make ATS-3 available, and one month before the expected arrival of the Pope in Columbia we were given the go-ahead.

Time was short; I moved my office into Lou Greenbaum’s shop and began work.  We needed almost immediate shipment of all components needed to build the terminal.  Lou and I drove to Fullerton to inspect the transmitter; it was OK so I asked that it be shipped to Lou’s shop that week.  The first problem came up the next day when the Purchasing department announced that no military terminal structure was available in less than six weeks.  They said a garbage truck tilt up box could be made available in one week. I said buy it, and tell them to put the ribs on the inside, panel it with mahogany plywood, and provide a strong roof and a door on one end. Next, I was told that the only 15-foot antenna available for immediate delivery was from Gabriel’s Horns in New Hampshire. I remember saying, “BUY IT!  God must be on our side”.

Testing Everything

Tom Hudspeth loaned us a prototype ATS spacecraft up and down frequency converter and the FM video modulator used to transmit Spin Scan Camera video. I borrowed a Boonton signal generator from the equipment pool to provide the FM voice subcarrier.  We borrowed the prototype of the VHF terminal installed on the Coast Guard Ice Breaker Glacier and built a 3-element Yaggi antenna to talk to Hughes from Bogota in case the phone lines were not reliable.  When the Fullerton transmitter was installed it would trip off in seconds after turning on.  This went on for about a week then I asked the technician Fullerton sent to install the transmitter, “What did you do different — it was working in Fullerton”.  He told me that nothing was changed except the directional couplers use in Fullerton had been borrowed so he installed new ones. I asked if he was careful to get the directional arrows on the directional couplers pointing in the right direction and he replied “what arrows?”  In ten minutes the transmitter was working again.  We tested the station, tracking the satellite, which was not perfectly stationary.

At first glance, one might think that we were forced to transmit blind since we could not possibly receive video on a 15-foot antenna.  Fortunately, the video signal has a very large amount of energy in the blanking pulse and this is transmitted at the 30-hertz frame rate.  We tracked the ATS-3 using this narrow band signal and plotted optimum antenna pointing angles with two carpenters tape measures mounted to the antenna gimbals.  Later in Bogota we used the VHF link to talk directly with the NASA ground stations to verify signal saturation levels in the spacecraft.  The station was flown to Bogota in a USAF C-130 and set up in less than one week.  Figures 3 and 4 show the terminal in operation in Bogota, Columbia.

The 15-foot antenna was dropped and dented during assembly in Bogota. We found a great body man who “made it all smooth again”.  He was right and it worked.

Operations in Columbia

Comsat insisted that Hughes had no license to transmit television signals through a satellite and that we should lease the terminal to them for the Pope’s visit.  I had adjusted the Boonton signal generator to provide voice signal levels about 1/10 the normal Comsat levels.  Their man on site in Bogota complained, also he also could not understand how we could possibly know when we were pointing our antenna at the spacecraft.  I knew the Comsat voice levels were unnecessary for acceptable quality and refused saying I wanted to make sure we had excellent quality video of the Pope. As to the antenna pointing, we had tracked the spacecraft for weeks, if the carpenter tape measures read correctly we were pointing at the satellite.  I knew NASA tested the VHF link every day so I could pick up the mike on our VHF terminal and ask for the microwave signal saturation level.  For the next 20 years satellite television quality was compared to BEST or “Bogotá Quality”

The Italian cameramen who accompanied the Pope had set up their control trailer next to our terminal. Early test using their video signal showed a troublesome amount of 60-cycle hum.  When this was pointed out, the Italian technical guy suggested that we tie both trailer and terminal together and drive a stake in the ground between them establishing a common ground. He also suggested that we disconnect the ground at the local power distribution transformer establishing the stake between our stations as the only ground. It worked.

After the successful transmission of the visit of the Pope to Bogota the first mobile satellite transmitting station went to Persia to transmit the 2500th anniversary of the Persian Empire in October 1971 to the world, then on February 5, 1972, a C-130 flew it to China for the historic visit by President Nixon .

I would like to thank The Bogota team which included Al Koury, Jim Burns, Jack Clarkson and Bernie Burns as well as those nameless others in Lou Greenbaum’s Satellite Command and Control Department who were vital in completing the terminal in 30 days.

I would also like to thank Howard Ozaki who provided the tunnel diode low noise receiver amplifier, Clovis Bordeaux Hughes Fullerton who provided the 10-kilowatt Transmitter, and especially Tom Hudspeth for his many valuable suggestions and “Loans”.

 

 

 

 

APPLICATION TECHNOLOGY SATELLITE – VHF EXPERIMENT ONLY–Roland Boucher

BACKGROUND

In early 1963 as a young 31-year-old engineer I was assigned the task of developing a method for mobile users to communicate through a synchronous satellite.  A brief study of the problem indicated that for truly mobile communications the user should be able to use a simple dipole antenna. This led to a company funded effort to demonstrate the reception of the one-half watt Syncom 2 VHF telemetry signal on a simple dipole antenna. On 21 February, the one-half watt Syncom2 VHF telemetry signal was successfully received on a dipole antenna. Three months later, on 8 May 1964, a teletype message was repeated through Syncom 2 telemetry and command system to a ground transmitter with a power of 19 watts using 12 and 14 db. gain Yagi antennas.

When news of these tests reached Frank White of the Air Transport Association he set in motion a series of events that led NASA to fund the ATS VHF Experiment.  His plan was to demonstrate two-way communication between a Pan-Am jet leaving Hong Kong with the NASA ground station at Camp Roberts California via the Syncom telemetry and command system.  On Jan 27 1964, these tests were successful and within weeks NASA funded the ATS VHF experiment.

The ATS-1 is the first of a series of five spacecraft built for NASA Goddard Space Flight Center by the Hughes Aircraft Company. The objectives of the VHF repeater are as follows:

• Demonstrate feasibility of providing continuous voice communications link between a ground control station and aircraft anywhere within the area covered by the satellite

• Demonstrate feasibility of providing a network in which data from small- unmanned stations or buoys are collected via satellite and disseminated

• Evaluate feasibility of VHF navigational systems

• Evaluate airborne and ground stations required in the above ­ mentioned networks

A fifth objective area was later added to demonstrate two-way voice and teletype communications from ships at sea anywhere in the satellite coverage area.
VHF REPEATER GENERAL DESCRIPTION

The VHF communications experiment is a frequency ­translation limiting (Class C) repeater receiving at a frequency of 149 Mhz and transmitting at 135 Mhz. The repeater both receives and transmits through an eight-element, phased-array antenna; Table 1 presents the repeater characteristics.

Operation of the repeater is as follows: incoming-signals at 149 mHz arereceived on each dipole element, routed through diplexers, amplified by a low-noise receiver, and shifted in phase to compensate for the relative position of each dipole antenna. The electronically controlled phase shifter in the receiver unit, driven by the waveform generators, causes the output s of each receiver to be in phase only for those signals originating from the earth. Reference sinusoids used to drive the waveform generator s are obtained from the same phased-array control electronics used to position the microwave beam toward the earth. The eight receiver outputs are summed together, filtered, down­ converted to an intermediate frequency (IF) of 29 megacycles, amplified, and passed through a crystal filter to limit the receiver bandwidth.

The IF is then amplified, up converted to 135 mHz, further amplified, and divided into eight equal parts. Each of the eight signals is routed to a transmitter where it is amplified, phase-shifted, and further amplified to a power level of 5 watts. Each transmitter output is routed through its respective diplexer to one of the antenna elements.

The transmitter phase shift is controlled by the waveform generator, which causes the signals from each antenna to reinforce in the direction of the earth. Provision is made to operate only odd or even sets of four transmitters, if desired, to reduce the DC power required.

It is also possible to drive the waveform generator from either the redundant Phased Array Control Electronics or to shut down this unit entirely creating a pancake antenna pattern, approximately 60 x 360 degrees that will encompass the earth during most parts of the launch trajectory and at all times after satellite reorientation.

The ATS spacecraft power supply and thermal design allow for continuous operation of the VHF experiment except during periods of eclipse. The repeater elements are supplied with -24volt and 23.4-volt regulated power. Switches are provided that allow operation of the equipment according to commands from the ground stations. Telemetered outputs are also provided which can be transmitted to earth either by the VHF or microwave telemetry systems.

The repeater is made up of nine subassemblies: eight units containing one transmitter, receiver, and diplexer; and one unit containing an up converter, down converter, waveform generator, and two voltage regulators. These units are shown in Figures 3 and 4.

TECHNICAL ADVANCES MADE BY ATS-1

1) The first VHF phased array in orbit

2) The first phased array to operate on both transmit and receive frequencies

3) The first deployable antenna on a spinning spacecraft

4) The first spacecraft repeater to use separate receivers and transmitters for each antenna element

The VHF antenna consists of eight full-wave dipoles arranged in a circle of one wavelength diameter (86 inches). Volume limitations in the Atlas-Agene shroud dictated the use of a deployable antenna. The eight-dipole elements were mounted on a radial arm attached to the forward solar panel and pivoted to place the antennas in a three-foot circle directly over the apogee motor nozzle during launch.

At separation from the Agena, the spacecraft is spun up; centrifugal force causes the antennas to deploy to the 86-inch diameter at 50 rpm. Deployment takes place during the normal spin up of the spacecraft without the use of ground commands.  When the spacecraft apogee motor is fired, the antennas are subjected to high Mach numbers and high heat fluxes. The rocket motor in the center of the array contains 750 pounds of propellant and burns for 40 seconds increasing the spacecraft’s apogee velocity by 6000 fps.

To withstand the severe thermal environment, the antenna elements were constructed of beryllium, flame-sprayed with aluminum oxide, and further covered with a Teflon ablative material. The high heat capacity of the ablative material and of the beryllium itself maintains the antenna temperatures below the unprotected equilibrium temperature of 3000° F.

IN-ORBIT PERFORMANCE

The following report is taken from a presentation given in May 1967 at a meeting of the RTCM in Las Vegas Nevada by Roland Boucher.

ATS-1 was launched into orbit on 6 December 1966.  The VHF repeater was first operated 3 days later. Since then, it has been used to successfully communicate voice and data between NASA ground stations at Rosman, North Carolina; Mojave, California; and Kooby Creek Australia. It has sent weather facsimile pictures and has been used to determine propagation properties of the ionosphere.

Simplex air to ground communication tests have been conducted with aircraft operated by Pan American, Eastern, TWA, United, American, and Qantas airlines as well as those operated by the FAA and the U.S. Air Force. Both simplex and duplex communications were successful with a shipboard terminal   constructed by Hughes. This terminal was leased to the U. S. Coast Guard and has operated successfully on the Coast Guard Cutter, Klamath at Ocean Station November in the Pacific Ocean which was described by a member of the U.S. Coast Guard.  In May 1967, the VHF repeater experiment had operated successfully for over 5 months with no signs of degradation.

Prior to the launch of ATS-1, there was considerable skepticism as to the feasibility of VHF satellite communications in mobile service despite the fact that nearly every satellite to date had used the VHF band for its primary mode of telemetry and weather photo video transmission.

SCINTILLATION FADES

The uneven diffractive properties of a disturbed ionosphere can cause deep fades at VHF frequencies. These fades are normally of a very brief nature lasting typically from 8 to 30 seconds. Examination of this phenomenon by Hughes Aircraft Company under NASA contract NAS-510 174 indicated that fades of greater than 6 db. depth could be expected 0.002 percent of the time in the mid-Pacific area, Tests with ATS – 1 during the first 5 months in orbit have failed to yield any statistically significant data on scintillation fades. The rarity of their occurrence makes it almost impossible to detect them in a normal push-to-talk circuit. They do not present a serious problem to this type of communications.

MOBILE TERMINAL NOISE

Mobile terminal noise was also cited by some as a nearly insurmountable problem as late as a few months before the ATS-1 launch. Tests on aircraft and on the cutter Klamath have shown this problem can be cleared up by normal RFI practices.

SEA WATER MULTIPATH

Multi-path fades were held up as an obstacle to VHF mobile communications with fades up to 30 db predicted. Tests with the ATS-1 to date have shown multi-path propagation not to be a serious threat. In examining the records of many hours of shipboard and aircraft communication, no clear evidence of multi-path propagation fades could be found. This despite the fact that Hughes intended to use the evidence of such fades as a requirement for the development of a new type antenna for the NASA/Hughes ATS C. The fades were not found. The antenna was not funded.

EARTH-NOISE TEMPERATURE

Earth-noise temperature was cited as a possible deterrent to VHF satellite communications. The proponents of this concept reasoned that many spurious emissions from the large number of earth transmitters would form a noise blanket which would jam the satellites receivers.

Measurements taken in late 1966 by Boeing Aircraft to determine receiver noise temperatures in flight from a commercial aircraft indicated that cities could be found quite easily by the noise they created. This noise was seldom evident more than 10 or 20 miles from the city centers. Noise temperatures even at relatively low altitudes seldom were in excess of 20 db. with a 10-db-background level being more nearly an average figure.

A simple calculation involving the area of the world covered by cities indicated that this noise would not be a serious problem at synchronous altitude. Corroborating evidence was the fact that most satellite command systems operate in the VHF band. Any serious problems in the uplink would certainly have been discovered before 1966.

The launch of ATS-1 proved this point. Up-link receiver sensitivity of the ATS-1 spacecraft is essentially that measured in the laboratories.

UNANTICIPATED PROBLEMS

The ATS uplink is in the land mobile band. In the early phases of the in-orbit test program, strong signals were heard in the satellite s passband. Many of these were conversations in English from what appeared to be military personnel. The conversations contained description of maintenance operations on jet aircraft indicating that a ground terminal used to communicate with mobile airport vehicles was transmitting to the spacecraft. Other signals in the spacecraft ‘s pass band that have been annoying at times have contained considerable 60 cycle modulation, indicating they originate from an earth borne transmitter.

None of these emissions proved detrimental to the test program after December 12. On that day, the severity of the jamming indicated that up link ERPs in excess of 2 kilowatts were present

A number of interested parties, through the cooperation of NASA and Aeronautical Radio listened for a one-week period in an effort to determine the origin of these strong signals. They were not present during this one-week period and have not returned. In the first 5 months as equipment and operating procedures have improved both in the aircraft and shipborne tests, this problem, which seemed so serious on 12 December, has been nearly forgotten.  Today VHF communications via satellite have been shown to be feasible for aircraft and maritime mobile application.

THE ATS-3 VHF EXPERIMENT

Spacecraft operating at microwave frequencies operate their transmitters well below peak power (transmitter Back-Off).  The VHF Experiment on ATS-3 Replaced the Class C RF amplifiers used on ATS-1 with linear RF amplifiers. This was important because it greatly reduced the inter-modulation distortion inherent in multi-channel transmitters. These transmitters were solid state and used a class A/B final stage; The DC power required was reduced 1/2 db. for every 1 db. of back off. This was a very important discovery since power is a very expensive commodity on any Spacecraft.

At low elevation angles multipath can cause a significant loss in signal for short periods of time as the reflected signal alternately cancels and adds to the direct signal. Circular polarization can eliminate this problem when used by receiver and transmitter that was later verified in field tests with TACSAT in 1969.

Hughes designed and tested circular polarized replacements for the dipole antenna elements on ATS-3.  Unfortunately, NASA did not approve their use.  Meanwhile Boeing designed a circular polarized flush mounted VHF antenna for the 747 aircraft.  C.A. Petry at ARINC worked with the airlines and FAA to produce a spacecraft compatible aircraft radio set in ARINC Specification 546.

When the first Boeing 747 was delivered to Pan Am, it was equipped with and ARINC 546 communication transceiver and a circular polarized antenna. This aircraft was equipped for satellite to aircraft communications.

ATS-3 was launched successfully on November 5, 1967, and positioned over the Pacific Ocean. Together with ATS-1 nearly global communications were possible at VHF frequencies.

Hughes designed a small inexpensive VHF terminal for the US Coast Guard that was installed on the USS Glacier, the ship used to resupply the Antarctic Base.  Sun spot activity was heavy during the 1967-68 winter, and HF radio was unusable for long periods of time.  The $4000 Hughes satellite terminal got through every time.

In the fall of 1969 I was selected as a representative of the State Department to the CCIR Conference on satellite communications.  Captain Charles Dorian and I were able to persuade the Russian delegate to support the US position to authorize VHF aircraft communications by satellite.  France led the opposition. The Russians brought along the eastern bloc, even Havana supported us. The French opposition was defeated – WE WON

Unfortunately, France played politics better than we did. As I understand it, they got NASA to oppose Aerosat in exchange for France support of the Space Shuttle. In any case, I received a phone call in Geneva from Hughes saying NASA pulled the plug – ITS ALL OVER.  I had spent nearly almost 10 years in the pursuit of a VHF Aeronautical Satellite to no avail.

At least the military did not have to play these politics.  Both Russia and the US adopted VHF communications (TACSAT).  The Syncom and ATS experiments produced at least two winners.

Completely independent of my employment with Hughes, I had developed the concept of an electrical powered battlefield surveillance drone and a Solar Powered high altitude spy plane. Dr. Bob Roney told me Hughes was not interested.

I left Hughes Aircraft in January 1973 and successfully proposed both aircraft to DARPA. The prototype electric powered battlefield drone flew that year and was shown on Los Angeles television. The 32-foot span proof of concept model of the spy plane flew on solar power alone in 1974.  A patent for the electric powered aircraft was granted on May 18, 1976.

POSTSCRIPT

On September 29, 1995, Ben McLeod and Bob Bohanon (Both from Pan American) organized a 30th anniversary celebration in Washington DC. Personnel from ATA, ARINC, Bendix, Comsat, FAA, FCC, Hughes, NASA and or course Pan-AM were in attendance. We all were all thrilled that the aging Frank White was able to attend and were sad that other important contributors from Comsat, Collins Radio, and the US Coast Guard were unavailable or deceased.

VHF COMMUNICATIONS EXPERIMENTS WITH SYNCOM 1963-1965

As remembered by Roland Boucher November, 2017

My involvement began in late 1963 when I was assigned to a team at Hughes Aircraft, that had been given the task of developing satellite communications applications. Syncom 2 was in orbit and the age of satellite communication had begun. As the junior member of the team, I was assigned mobile applications. A brief study of the problem indicated that for truly mobile communications the user should be able to make use of a simple dipole antenna (or aircraft blade antenna) and that the optimum frequency would be in the 150 MHz to 450 MHz range. The telemetry and command system of Syncom 2 operated in the VHF band at 136 MHz and 148 MHz this led to the proposal to use this spacecraft to demonstrate satellite to aircraft communications.

This document describes the efforts by personnel at Hughes, NASA, Air Transport Association, Bendix, Pan Am as well as the FAA and the US Weather Bureau.  Significant early contributors were Frank White (ATA), William Pulford and Harry Betsill (Bendix), Meredith Eick, Lou Greenbaum and Roland Boucher (Hughes), Ben McLeod, Bob Bohanon and Waldo Lynch (Pan Am), Pat Corrigan and Bob Darcy (NASA Goddard) and members of the antenna department at Boeing.  Many other organizations were to become involved over the next nine years.

In early 1964, a simple test program was initiated to obtain first-hand information on the properties of VHF satellite communication. On 21 February, the one-half watt Syncom 2 VHF telemetry signal was successfully received on a dipole antenna, thus demonstrating the successful reception of very weak (-142 dbm) signals by a standard telemetry receiver.

On 8 May 1964, the first teletype message was repeated through Syncom 2 at VHF frequencies, the ground transmitter had a power of 19 watts and the receiver a noise figure of 3.5-db, transmitter and receiver antennas were 12 and 14-db Yagi’s.  During the interval between these tests, two Boeing engineers received Syncom 2 telemetry while gliding over Puget Sound in a light aircraft (Aeronca Champion).

News of these tests reached the airline community, Frank White of the Air Transport Association set in motion a series of events, which eventually led to the ATS-1 VHF experiment on 27 July 1964.

Mr. White called the kickoff meeting of what he called The Interim Communication Satellite Committee. representatives of the Air Transport Association, FCC, FAA, NASA, Pan American World Airways, Bendix Radio, Boeing Aircraft, Comsat, and Hughes participated.  Mr. White’s plan was simple — demonstrate two-way digital communications between a Pan American jet aircraft in commercial service over the Pacific Ocean and the NASA-Hughes ground terminal at Camp Roberts California via the Syncom 3 satellite. The program moved swiftly.

On 19 August, 3 weeks after the program began, a modified Bendix aircraft receiver picked up the Syncom 3 telemetry signal as the spacecraft rose from Cape Kennedy in the first successful launch of a geostationary satellite.

On 21 September, 5 weeks later, the Syncom 3 telemetry was received aboard a PAA Boeing 707 enroute from San Francisco to Honolulu. The first digital message transmitted from a synchronous satellite to a commercial aircraft was demonstrated on that day.

On 27 January, exactly 6 months from the beginning of this ambitious program, the first two-way digital communication link between a ground station and aircraft via a synchronous satellite was established.

The first flight test took place over the Pacific Ocean in a Pan AM 707 aircraft. Those on board were Waldo Lynch a vice president of Pan American Airways, engineers Harry Betsill and Bill Pulford of Bendix Radio, and Roland Boucher of Hughes.

Operational tests were conducted that day during a flight from San Francisco to Honolulu, Harry Betsill remained on board conducting 3 hours of two-way communications between the aircraft and the NASA ground station at Camp Roberts California. NASA at both its Australian and Alaskan tracking stations monitored these transmissions. The aircraft with Harry continued on to Hong Kong.  On the return flight, it transmitted nearly perfect teletype copy at 60 wpm to the Camp Roberts terminal.

The success of this test program and the potential it demonstrated for mobile satellite communications led to the decision by NASA to Fund the first VHF repeater experiment on the ATS satellite.

Within weeks of the test of January 27 NASA asked Hughes to develop a VHF repeater experiment for the NASA/Hughes Advanced Technology Satellite ATS-1.  This experiment was managed by at first Bill Penprase then by Roland Boucher at Hughes. Pat Corrigan at the Goddard Spaceflight center was NASA program manager.

I am sorry that I am quite fuzzy about events at this time.  When returning home from the flight tests on January 28, I was told that my father had contacted meningitis at his home in Connecticut.  He died after a brief illness. The next event, which I really remember, was the solution to an ATS antenna temperature problem.

 

Hughes Launch Log 1963-2000–Jack Fisher

This is  a compilation of all unclassified Hughes Aircraft launches from the first launch of Syncom in 1963 through the calendar year 2000 in chronological order.  It is a work in progress and I solicit inputs and corrections from all.  I believe that I have included every unclassified launch and only status data is needed.  I have added the three HS-376HP launches that were conducted by Boeing 2000-2003.  Please review this and help me add to our log.

 

 

 

 

 

 

 

SATELCO: A Joint Venture of Hughes and NEC into the INTELSAT Ground Station Business—Joe Freitag With some added comments by Joe Moore

I was involved in the founding, development and operation of SATELCO. It was an exciting period in the quasi-commercial implementation of international satellite communications.   I have been asked by longtime friend Boris Subbotin to share my experience with others interested in the extraordinary days of Hughes Aircraft Company. What follows is my recollection of the people, the events and the dates of the activities. I hope I have acknowledged the contributions of the contributors, identified the events that shaped SATELCO, and I hope the dates approximate the times of the episodes.  

The success of the Syncom satellite built by a talented and dedicated group of people under the guidance of Dr. Harold Rosen in the Space Systems Division, stimulated many ideas, to promote the development of geosynchronous satellite systems for the betterment of mankind. One of those ideas was the formation of the Hughes/NEC Satellite Telecommunications Company, (SATELCO). The following paragraphs tell the story of its formation and eventual demise as I remember and includes edit comments from Joe Moore. Comments from others that might remember other details of this amazing chapter in the life of the SATELCO story are always welcome.

In the 1960’s the United States and the USSR were engaged in a cold war and a war of words on the benefits of a capitalistic society versus a communistic society. Offering global communication connectivity via a U. S. designed satellite system was a means by which President Kennedy could demonstrate the advantages and benefits of a capitalistic system to the world. The U. S. State Department was empowered to develop a treaty organization of non-communist governments, to share and own this satellite system. The treaty organization was named the International Telecommunications Satellite (INTELSAT). Each government would authorize their overseas telecommunications operator to subscribe to and take membership size depending upon the amount of international traffic conducted by that country. INTELSAT provided the means for all member countries to plan the amount of circuits needed between each pair of countries. INTELSAT would also procure the satellite but rely on the U. S. entity, COMSAT, for providing technical assistance in managing the procurement, deployment and operation of satellites. COMSAT represented all U. S. carriers that provided international communication and therefore became the largest shareholder, based on traffic, of INTELSAT.

COMSAT sold stock to finance the building and deployment of the satellites before it was determined if INTELSAT would select either a Geosynchronous Satellite System like Syncom that had been built for NASA by Hughes or a Near Earth Orbit system like the AT&T Satellite System or the Relay Satellite System that had been built for NASA by RCA.

All of these events came together when Hughes was selected to build the EARLY BIRD Satellite for INTELSAT. The State Department announced it was inviting representatives from each of the member countries to send delegates to Washington DC for a Technical Seminar explaining Satellite communications with emphasis on how to procure a ground station to operate with the satellites and tie it into their existing overseas telecommunications networks. As I remember, it was April 1965 when this took place and every vendor pitched his ground station or supporting product around the figure of merit called G/T for a receiving and transmitting antenna system.

Hughes International under the direction of General Shoup (USAF Ret.,) had been following the developments at the Department of State. Harold Rosen’s lab together with Dr. Begovitch and Mr. Brubaker, deputy and head of the Ground Systems Group were responsible for developing an antenna mount that would avoid the more expensive Polar or Azimuth over Elevation mounts used for Astronomy, Radar and other applications that required movement to track an object in space. With a geosynchronous satellite system, these expensive mounts could be eliminated. The resulting development was a simple and less expensive “Wheel and Track” mount system for the geosynchronous satellite. Hughes had something to sell that would enable the early acceptance of the geosynchronous satellite system.

General Shoup’s organization earlier had established relations with Nippon Electric Company, (NEC,) to deploy the Hughes Air Defense System.   NEC had developed new digital telephone switching gear and was looking for another market for this product.   Dr Puckett and Mr. Roy Wendahl, executive VP’s were involved and a decision was made to form a new subsidiary joint venture company with NEC focused on the international telephone operating companies that would be customers for the INTELSAT system.

It was decided to separate SATELCO, selling a commercial product from Hughes International, which was in the business of selling TOW Missiles, Air Defense Systems, radars and other defense electronics. General Johnson (USA Signal Corp Ret) was hired to be the SATELCO President reporting to Mr. Roy Wendahl, and to hire a Marketing VP with international commercial sales experience from outside the company. They selected Mr. Steven Barrie, a multi-lingual Swede by birth, but a naturalized U. S. Citizen with extensive international electronic marketing experience. Barrie was a gregarious, enthusiastic individual, who could win the attention of any roomful of personalities. He looked for people to fill the organization with carte blanche from General Johnson and Dr. Kobyashi, (CEO of NEC,). Carpeted offices outside of Hughes in a commercial office building were furnished with wooden furniture instead of ordinary “Hughes Steel”. He hired me as his deputy for coordinating with Hughes European Offices and the Middle East and African Market. Al Apodaca was hired to handle Central and South America and Gus Cano, from Peru, became the field representative working with Apodaca.   Willie Kamei, another outstanding individual from Hughes International coordinated meetings with NEC and marketing opportunities in Asia.

The technical staff consisted of Bob Scrafford from Harold Rosen’s lab and his deputy Jack Shaw. Joe Moore, Al Koury, Bob Walp, Ed Enriquez and several others were part of Scrafford’s organization.   Scrafford led his group to design a lower cost antenna with Dr Nick Begovitch’s Ground System Group in Fullerton.   In addition, Dr. Sam Lutz from the Hughes Malibu Research Laboratories provided many technical papers justifying the use of the Geo-Synchronous system, the simplicity of the SATELCO antenna and won the minds of many potential customers for the adoption of this new concept in satellite global telecommunications.

We were briefed on the upcoming April Conference at the Department of State and instructed to became acquainted with the foreign telecommunication delegates who would be our future customers. The U. S. Export Bank was prepared to make favorable loans to developing countries purchasing U. S. ground stations. Also involved were the international overseas telecommunication companies from Canada, France, Germany, Italy, United Kingdom and others I don’t recall.

To support the State Department Conference, Hughes offered to fly delegates to Cado Gap, Arkansas where Hughes would install the first “Wheel and Track” mounted antenna and NEC would install their new state of the art digital switching equipment. Undoubtedly there were probably several reasons for selecting Arkansas. Primarily the Hughes/NEC decision to demonstrate in Arkansas supported the idea of a better technology in a remote location. The then current HF Radio systems for international communication that were located in major cities generally near a coast. Hughes participation in this demonstration, supporting the success of INTELSAT, furthered the goal of President Kennedy to demonstrate to the free world, the benefits of capitalism over communism.

I was then a 3-year employee and impressed by the Hughes Executive commitment to SATELCO and the “sport” of challenging the International and U. S. telecommunication carriers that dominated the international telecommunication business throughout the world.   I personally felt that this was an opportunity for me to “make a difference” in the way international communications was conducted.   The British and French International telecommunication carriers that routed all traffic between London and/or Paris dominated telecommunications to and from the Middle East and Africa. (If you were in Cairo and wanted to call someone in Beirut, your call went to London, was routed to Paris and Paris made the connection to Beirut.)

Following the events at the Department of State, Hughes chartered planes to fly any delegate attending the DC Conference to Cado Gap (near Hot Springs) for the demonstration of the first “International Telephone Switching” center in Arkansas.   The point was that a satellite-switching center could be located anywhere in the world. The Arkansas location was a Hughes poke at the U. S. companies handling international communications like AT&T, ITT, Western Union, and RCA Globecom, relying on HF radio or undersea cable communication, that had made major coastal cities like NYC or San Francisco their operating centers.

Because my hosting responsibility in Arkansas included Africans and Middle Easterner delegates, I was concerned about how to safely dine and entertain them in the strongly social prejudicial areas of Hot Springs.  I was assured by State Department officials that restaurant owners and club owners were given the word to treat the visitors properly and that there would be lots of plain clothes State Police around to avoid any incidents. Hughes Corporate Staff planned an elegant affair that was quite impressive.

The demonstration of “Wheel and Track” mounted antenna and the NEC equipment and the inspirational comments of innovation, and technology providing new opportunities for developing countries from the Hughes and NEC Executives were as exciting as a rallying political speech.   At this point, the delegates were clapping and cheering the messages they heard.   My delegates turned to me and said, I want you to come to my country and I will arrange all the meetings you need to make a sale!

But the Cado Gap event was not over. The Arkansas Senators talked next. They graciously thanked this wealthy company from Los Angeles for bringing this expensive and impressive demonstration of the future and bringing these delegates to the beautiful state of Arkansas.   They hoped the delegates would enjoy their time in Arkansas and assured them that they would be safe.   Then they attacked Hughes as a company that used their connections in Washington D. C. to influence Defense budgets. They alluded to the fact that they believed Hughes was doing this to get favorable support from these Senators for a future Defense system.   These remarks threw cold water on the images that Hughes had created.   Delegates heard the message of influence and thought about what they had experienced under the British Post Office and French Cable and Radio.   Puckett and Wendahl handled the criticisms with grace and concluded the event by being available during the demonstrations of the Antenna System and the Switching Equipment.

As had been promised, the delegates were treated graciously and with friendliness by the local hotels, restaurants and clubs. There were no incidents and the next day, Hughes flew the delegates back to DC where they caught their flights and took their impressions back to their home countries.   Each delegate got a token gift of a set of cuff links and tie clasp picturing the Early Bird Satellite and the SATELCO Ground System.SatelcoJewelryNot long after the conference, General Johnson became disturbed with the free rein he had been given by Hughes management. Although Hughes and NEC financed SATELCO, the Hughes contributions came from Fred Adler’s Space Systems Division, General Shoup’s International Organization and by Nick Begovitch’s Ground System Group. They were responsible for accounting for these expenses.   Johnson, a bit skeptical of SATELCO, wanted a goal and a budget – not an open checkbook from various entities within Hughes. He eventually resigned and Mr. Ed Sheridan, a former Aerospace employee that had been hired by Ground Systems Group, was appointed President. Ed accepted the job but he never had confidence that SATELCO would be a financially successful company. He did improve the technical content of our proposals and tightened the contractual terms that were being offered.

Under Steve Barrie’s marketing guidance, the decision makers in the countries that were prime candidates for INTELSAT satellite communications became known to SATELCO. Local agents that were hired in these countries were either well connected to the decision makers or were current suppliers to the local PTT. SATELCO’s agents explained such things as the decision process in their countries, the politicians that wanted payoffs, and the activity of the competition. Using traffic data, SATELCO developed economic studies, and presented the results to the decision makers. SATELCO provided information to help the target countries prepare “tenders”. Technical representatives visited SATELCO offices in Los Angeles.   They were impressed with the technology developed by Hughes, but they voiced their concerns that Hughes wouldn’t stay in the telecommunications business and be available to assist them in further implementation of a satellite system that could also be used for domestic communications. It soon became clear that the British and French had technical staff in each of their former colonies. These in-country representatives were advising the Minister of Communications of the risks involved in adopting a Satellite communication system and relying on Hughes (SATELCO) solutions.   Apodaca and Cano reported similar concerns in Latin and South America. Like the European overseas operators, the U. S. overseas carriers wanted to protect their business relationships that were threatened by the INTELSAT system. Although NEC could have supplied all the highly respected telecommunications equipment required, the Japanese Trading Companies representing them were companies who handled all of Japan’s export markets. None were specialized in, or knew much about the telecommunication business.

Uncertainties in how to proceed in these countries caused the procurement dates to slip. None wanted to be first. The European countries (UK, France, Germany and Italy) were the first to implement satellite communication by installing very sophisticated and expensive satellite ground stations by domestic manufacturers. Neither “Wheel and Track” antennas nor NEC switching equipment were achieving the customer interest that had been expected. The in-country SATELCO agents were pressing for payoffs but there was no interest on the part of Hughes management to be involved directly in any payoffs. (Thank goodness!) Some agents believed that if a sale was made, their commissions could be structured to cover any payoffs.

Two and a half years went by without any sales. RCA Canada, UK and French manufacturers made sales. Talk of disbanding SATELCO was being discussed. Mr. Wendahl was more involved in the oversight and he appointed Mr. Waldo Neikirk to report to Ed Sheridan and provide financial and administrative oversight management to SATELCO. Steve Barrie was fired. It was clear that it was a matter of time before an honorable solution to dissolve SATELCO, satisfactory to Hughes and NEC, would be found. It was decided to put an all-out effort to win Peru, Brazil and Argentina.   Paul Visher got involved, delivered the proposals and negotiated the offers. I felt it was time to find another job and left honorably having a very nice exit interview with Mr. Wendahl in 1968. He acknowledged that oversights that had been made in the formation of SATELCO.

Joe Moore informed me that Peru, Brazil and Argentina proposals were bid as “loss leaders” with the hope that the amount of loss could be lessened by building all three together. This would eliminate separate crews making the installations during different time periods. The offers to Peru and Brazil were won. STS, an Italian Company that had a major earth station in the INTELSAT System was awarded the Argentinean contract. According to Moore, the Italian Government threatened to stop importing Argentinean beef if the Italian proposal did not win.

According to Moore, SATELCO then proposed to “Unwin” the Peru proposal and give the contract to NEC. Shortly afterwards, HUGHES Communications International signed a contract with Brazil on the 22nd of December, 1967 to build the Brazilian type “A” earth station. A small group was formed to implement the contract. Bob Scrafford was head of the group assisted by Lloyd Ludwig. Lou Greenbaum assisted by Al Koury was head of the engineering department. This group was located on 2311 Utah Ave. in El Segundo. It is my understanding that Lou’s group began building and selling test equipment. Lou had done an outstanding job in building the TT&C equipment for Syncom and Early Bird.

Like many others, I feel very grateful that I began my career with Harold Rosen’s Syncom Project. Syncom was a truly global system that led to many commercial, civil and military satellite based systems. It has spawned many businesses and services that didn’t exist until satellite systems were deployed.   Like many other individuals, I had the opportunity to get to develop these new businesses. Like Syncom and SATELCO, each had a set of risks associated with them. Some of these ventures requiring investment were successful like Syncom, and in others, like SATELCO, failed because of the political and establishment risks that materialized. But who can deny that the journey in the evolution of Syncom systems was of great benefit to society and that participation in the evolution and spin-offs was anything short of exciting, fulfilling, and satisfying through the association of many talented and dedicated individuals during a life-long career with this technology?

The Enduring “SMART” Satellite Manual–Jim Thompson

I joined Hughes in mid June 1964 on the Masters Fellowship Rotation Program in the satellite area as my first rotation. Within a week or so another new hire named Mickey Haney showed up with an MS from MIT. It was an exciting time to start at Hughes Space Division. The Earlybird contract was recently awarded as the world’s first commercial satellite program. Syncom II was successfully operating in orbit and Syncom III was about to be launched.

As new guys Haney and I were doing a lot of calculations on ground station look angles (azimuth and elevation angles) as function of location relative to the satellite, as well as the satellite return look angles to the ground station.  We also collected agreed-upon values of basic parameters like earth radius, geo-stationary orbit radius, and orbit equations for synchronous inclined orbits. As systems engineering people had need for different ground station locations, we ended up repeating calculations for each case. That led to a set of charts where one could read the satellite or ground station look angles for any location in the coverage region. These were the days of the slide rule for most engineers and no pocket calculators. Fortunately there was a time-share computer system one floor away where one could program in Basic to generate the data for these graphs. Charts for other geometric parameters quickly followed. We also learned about link budgets, the details of the various contributing factors in the budget, and communications capacity calculations. We made charts for many of those parameters. Clearly the work involved learning some basics of satellite communications.

Soon another individual, Dr. Boris Subbotin, transferred from what had been the Hughes Communications Division. He was a senior scientist and in addition to his other duties he was given the task of keeping Haney and I productively occupied. Boris suggested that we compile a handbook on communication satellite parameters. It could be as simple as some content in a monthly industry trade magazine called Microwave Journal which usually had some graphs or nomograms in each issue, or a hardcover year end yearbook with a collection of technical charts. We started with a three ring binder version that could begin with modest content and grow as demand and utility needed. Boris recently stated that he liked the idea for three reasons: 1) he had no work to keep us fully occupied at the time, 2) he noted that most of the engineers in the area had their own private collection of notes, shortcuts, references etc. that they might share if a handbook was in the works, and 3) it would be a good learning experience for us.

We thought it would be nice to have a catchy name for handbook, some kind of acronym based on words representative of the content. So we filled a blackboard with words like space, satellites, Syncom, communication, technology, data, tools, charts, information, reference, book, handbook, text, manual, etc. We made lists of candidate acronyms and in the end we selected one suggested by Boris.   Thus the SMART manual was named with SMART standing for ‘Satellite Manual and Reference for Telecommunications”. We made up an outline and by Nov of 1964 issued an IDC requesting input for a handbook with four sections.

Inputs came in over time, but nearly always needed some explanatory notes, at least for us new guys. We worked on this task part time during 1965, took what came in, and asked for help explaining it. It was reformatted if necessary and added to the handbook. By year end we had enough content for a first release. The publications people printed and assembled some 50 to 100 copies in three ring binders. We distributed these first SMART manuals with red bows just before the 1965 Christmas Holiday.

People apparently found SMART useful not only for its content but also as a repository for their own favorite pieces of useful information. We solicited additional input and received material to be included in future updates. These were sent out every few years. Mickey and I eventually wandered off into programs or other assignments. The Systems Engineering folks in Leo Stoolman’s organization apparently took on the task of updating SMART, their first being in 1975. They also handed out copies to new engineering hires starting in the mid 70’s. Scientific calculators became available during the 70’s, but the manual was still useful. Equations were often provided with charts for those who wanted higher precision using the calculators.

By 1980 the amount of new material accumulated was substantial and SMART needed a major overhaul. Marty Gale was given the task of reorganizing and issuing the updated version. Additional sections were added to the manual, which resulted in a rather hefty volume. A separate book was added consisting of satellite maps of Earth as viewed from geosynchronous orbit in 5-degree increments of longitude for a total of 72 Earth maps. Overlays were included to provide information on polarization angle, elevation angle, and coverage limits. During the 1990’s a simple plastic slide rule was designed and issued to replace the book of maps. It was compact, easy to use and also served as a useful gift to customers.

Other reference materials (usually power point presentations) were generated by many departments within the organization as training material for new or old people. In some instances the company provided training to customer staff as part of the satellite contract. By the mid 90s there were probably two dozen well-developed departmental training packages. Computers were available throughout the company in this time frame. Many engineers developed their own tools for mapping (LEO, MEO or GEO), sophisticated link budgets including rain fade statistics, modeling of non-linear devices and Monte Carlo simulations of just about any kind of random event. Today these tools are called apps.

In the 1990’s Macs and PCs were in wide use throughout Hughes S&CG. The use of software to create a digital version of SMART would offer the advantages of improved accuracy via direct use of the relevant equations, and portability via laptop or compact storage medium. However resources were not available at that time to support this effort. I personally used two small notebooks with 3.5 by 6 inch pages to house my portable SMART manual. In 2005 I arranged for a power point version of the SMART manual plus a large collection of the appropriate reference material to be included in Boeing’s knowledge management database project by Mike Whelan. The references were cited to give users knowledge of any assumptions or limitations on the use of the content. I retired shortly after the last update. Today employees can carry their SMART manual around on their (also smart) phone.

It is remarkable that something simply started as a part-time project in 1964 would survive and still be useful 50 years later when updated to provide terchnically current content via technically current presentation media.

Comment by Felix Yin

Thanks for making this great site. I joined Hughes back in 1996 as a co-op student out of the University of Illinois. Though there were many employees that insisted that the golden days of the company were long past, my time there was really special and there isn’t a month that goes by that I don’t think about the great projects and people I got to work with before I left in 2004. Jim Thompson is one of those great people I got to work with and I love that he submitted a post about the SMART manual. I learned so much from that, much more practical than anything from my college education! And Jim downplays his little notebook. I will never forget being amazed whenever Jim would pull out his little notebook while we payload engineers were working proposal designs… he’d look at some lines in a graph and throw out some estimate of mass, power or cost… we’d take note and then go back to our offices to run a calculation in our, at the time, fancy excel workbooks, only to find that his quick and dirty assessment was pretty much spot on! Great times! Glad to see Jim is doing well!

 

 

SYNCOM’S REMARKABLE TRAVELING WAVE TUBE—Dr. Boris T. Subbotin

There is little doubt that several key available technologies in the 1958-9 post Sputnik era made possible the design and feasibility of the innovative and revolutionary Syncom synchronous communications satellite. One was the traveling wave tube, TWT (or TWTA). It is the device that provides sufficient radio frequency power in the satellite to be radiated by an antenna and be received on the ground. It consumes the majority of the DC power provided by a satellite and its batteries. The evolution of the space TWT has been of major importance to all space programs since the pioneering Syncom and Telstar in the early 1960’s.

There were, of course, several other technologies at that time that were essential to the Syncom concept. Included are solar cells, transistor technology, nickel cadmium batteries and the creative design breakthrough of a spinning body with axial and radial pulse jet control (the Don Williams patent). However, it was fortuitous that Hughes was also doing research in microwave power devices because of its core business in airborne and surface radars and missiles. The Research Laboratories (HRL) located in Culver City at the time, under Dr Andrei V Haeff, was the primary Hughes center for TWT developments.

The evolution and design of the TWT had taken place in many steps and places over the previous quarter century. The US centers were primarily RCA, Bell Labs, Stanford University, and HRL with several other lesser players also spanning and post WWII. The major contributors were Haeff, Nils Lindenblad, Rudolph Kompfner, John Pierce, and Lester Field. John Mendel of HRL (my classmate at Stanford) was responsible for the Syncom tube development. Some consider the TWT as the purest realization of the microwave generation principle in electron tubes. Further, it still employs the most challenging technology amongst microwave tubes** necessitating both Swiss watch precision and launch vehicle ruggedness.

If a narrow focused electron beam is sent at a speed slightly faster than a signal through a long coiled wire (delay line) in an evacuated tube, electron beam energy is transferred to the helix wire and signal amplification will occur. Electron beam design, generation, focusing, containment and collection, signal coupling in and out, suppressing unwanted reflections and oscillations, power handling and cooling, efficiency, maintaining vacuum, and numerous other design, materials, and lifetime issues are deeply involved in long life TWT design. For Syncom, Mendel developed a metal tube envelope and used a series of small annular magnets for beam focusing resulting in a S-band tube of 2 watts output.

TWTs have benefits that allowed them to still be the predominant space RF power output devices of today. Their DC to RF efficiencies have climbed from a nominal 10-15% to 65-75%, the signal amplifications from 30db to 50db ranges, and RF power outputs from 2 watts to several hundred watts. Parallel operation of TWTs for doubling output power was first used by Hughes on Intelsat II and is currently offered by suppliers. Since TWTs are not inherently coupled to resonant circuits, tubes may cover octave bandwidths. Today useful space frequency bands of operation encompass L, S, C, Ku, K, and Ka bands, from 1 GHz to over 40 GHz. Another beneficial characteristic is that they can be made low noise devices and used for receiving signals. Even just now, DARPA has issued an industry invitation to develop the next generation of TWTs.

The total number of satellite TWTs in orbit today approaches 25,000. In orbit tube failures are still improving and have been minimal, estimated at 2%, but may be governed by power supply failures rather than the TWT itself.

Hughes former Electron Dynamics Division in Torrance, CA, now L3 Communications Electron Technologies, together with the French-German Thales are the dominant suppliers of today. Not much has been published by the Russian and other suppliers.

The TWT is a remarkable device, selected with great insight, and continues to be an important part of our space heritage.

**Vacuum Electronics: Components and Devices  Edited by Joseph A. Eichmeier, Manfred Thumm

 

Configuration Management—Jack Fisher

Configuration management (CM) is a mystery to almost everyone as it was to me when we starting working on the Pioneer Venus contract in 1974. This was a serious concern as I had been chosen to head systems engineering for the program. My first stop in the quest for understanding was the company management directives. I spent the better part of a week reading and trying to understand these with little success—they were incomprehensible. My next step was to talk to Mal Meredith, my systems engineering mentor—Mal at that time was heading systems engineering for the NASA OSO program and he surely would be able to help me. His answer—don’t worry about it—it’s really very easy to understand and when it becomes important you will pick it up quickly. Needless to say this advice was very welcome.

Configuration management had its origins in the 1950s as the Air Force was developing ballistic missiles. A missile failure would require fixes resulting in a successful launch, but if the fixes were not properly documented they perhaps could not be replicated. CM begins with the formal release of program documents and drawings and requires that modifications be classified and formally controlled so that the product configuration is always known and under control. When the system is to be delivered to the customer its performance and configuration have to be reported.

We started the program and worked the major design issues and advanced into program engineering with the release of specifications and drawings. And this occasioned the need for control of the configuration or configuration management and the appearance of Mike Chekel. The NASA Division had a CM group that Mike headed. We started having weekly Configuration Control Board (CCB) meetings that I was expected to chair. Responsible Engineering Authorities (REAs) would propose changes to modify their subsystem design and the CCB would have to evaluate and cost them making sure that if other subsystems were impacted their REA would evaluate the change. With Mike’s guidance and meticulous record keeping we handled this phase of the program without any major difficulties.

The next hurdle was the Orbiter Pre-Ship Review that was held over a four-day period, February 21-24, 1978. It was chaired by Charlie Hall, the ARC program manager, and attended by representatives of various NASA centers, GDC, the launch vehicle contractor, and the experimenters that provided instruments for the mission. The purpose was to show that the spacecraft met all specification requirements and that we knew precisely what items comprised the spacecraft to be delivered. With Mike Chekel’s support we passed those hurdles with flying colors. Systems engineering prepared a System Performance Assessment Document (SPAD) that summarized spacecraft performance versus the requirements.

We later received a commendation from Charlie Hall, the ARC program manager that thanked us for “a job well done.” The orbiter was shipped to the KSC launch site on March 15 and was launched on its way to Venus on May 20. I left for the Cape in early March and headed up the systems engineering activities at the launch site. I returned briefly to El Segundo for the Multiprobe pre-ship review April 24-29. The Multiprobe was shipped to the launch site on June 5 and was launched on August 8. With Mike Chekel’s guidance I didn’t find that configuration management was all that difficult.

The Syncom III Mission and Spacecraft

 Note: This material is taken from NASA Technical Report TR R-252, Syncom Engineering Report Volume II with some editing.

This Syncom Engineering Report, is based on material furnished by the Hughes Aircraft Company and the U. S. Army Satellite Communications Agency, and will cover the launch of the Syncom III satellite, its performance during the first 100 days in orbit, televising of the 1964 Summer Olympic Games by means of the satellite, and various communication tests conducted with it. Syncom III is one of three communications satellites designed and built by Hughes for the Goddard Space Flight Center which have been launched into synchronous orbit. Syncom I was successfully launched in February 1963, but radio contact with the spacecraft was lost shortly after the apogee motor was fired, probably because of an explosion of a nitrogen control system tank. Syncom II was successfully launched in July 1963, becoming the world’s first operational synchronous satellite. This satellite was eventually placed at an area of low perturbation forces over the Indian Ocean after all control system propellant had been expended. From this position it has provided communication links between the Far East, Africa and Europe.

After the launch of Syncom II, the following modifications were made in the Syncom spacecraft:

  1. The nitrogen control unit was replaced with a second hydrogen peroxide control unit.
  2. The apogee motor timer was deleted and redundant provisions were made for a firing by ground command.
  3. Four temperature sensors were provided instead of the previous two sensors.
  4. The standby battery was eliminated.
  5. The P-N type solar cells were replaced by N-P cells and the 0.006-inch cover glass was replaced by 0.012-inch fused quartz covering.
  6. The 500-kc bandpass communications channel was eliminated and replaced by a 10 Mc bandwidth channel for television tests with a 50-kc option for small station testing.

Prior to the Syncom III launch, booster thrust limitations precluded any attempt to reduce the inclination of the Syncom orbit with maneuvers during the boost phase of launch. As a result, Syncom II, although in a synchronous orbit, moves 32″ north and south of the Equator daily. The ultimate objective of synchronous communications advocates has been to place a satellite into synchronous orbit in the equatorial plane. The satellite would then appear to remain stationary and would permit the use of fixed ground antennas without the expense of costly tracking systems. The achievement of this objective by Syncom III became possible with the development in early 1964 of the higher powered Thrust Augmented Delta launch vehicle that could provide enough thrust to permit in flight maneuvers to decrease the orbit inclination.

With the Summer Olympic Games of 1964 scheduled to be held in Japan in early October, the use of Syncom III to present live television coverage of the Olympic Games for the American public became a second launch object.

Syncom III was launched on 19 August 1964 from Pad 17A at Cape Kennedy, Florida. The launch was near-perfect. The maneuver to reorient the third stage for firing at the Equator crossing was also near-perfect. Third stage burn was good, but coning was experienced after burnout. Syncom III separated with a 14-degree attitude error. Seventeen hours and fifteen minutes later, as the spacecraft approached its second apogee over South America, this error was corrected and the spacecraft was oriented to the proper attitude in preparation for apogee motor firing. At third apogee, 29 hours and 2 minutes after liftoff, at a point above the Equator in Borneo, the apogee motor was fired. Syncom III went into synchronous equatorial orbit and later was maneuvered to a position above the intersection of the Equator and the International Date Line.

Since the launch of Syncom III, the following achievements have been recorded, demonstrating the operational and economic advantages of the synchronous communication satellite:

  1. The satellite was put into synchronous equatorial (stationary) orbit over the International Date Line. Ground stations are able to acquire the satellite and lock their antennas in place.
  2. The first 24 hour-per-day, 7 day-per-week reliable communications network has been established across the Pacific Ocean.
  3. Live television of the Olympic Games from Japan was a technical success.
  4. The first communications through an orbiting satellite to a commercial airliner in flight was demonstrated.
  5. The narrow bandpass transponder (50 kc) has provided small-station communications capabilities.

The performance of Syncom III has been excellent and no malfunctions have occurred. The satellite has been in almost constant operation since lift off. The only times the transponders have been off was during apogee motor firing and for a few hours each day when the satellite was in the eclipse season.

 SPACECRAFT DESCRIPTION

The Syncom spacecraft shown in Figures II-1 and II-21 is a spin-stabilized vehicle incorporating electronic, propulsion, and control elements, plus an electrical power supply and a structure. These are described briefly in the following paragraphs.Syncom S:CCommunication Subsystem

The communication subsystem is a redundant, frequency-translation, active-repeater system. Incoming signals from either one or two ground stations at a frequency of approximately 7400 Mc are received by an antenna with a pattern which is symmetrical about the satellite spin axis.

These signals are supplied to two receivers, only one of which is operating at any one time, the desired receiver being selected by command.

Both receivers are wide band, one with a bandwidth of 4.5 Mc between half-power points and the other with a bandwidth of 13.5 Mc between half-power points. In addition, the bandwidth of the 13-Mc receiver can be switched to 50 kc.  Each receiver consists of a mixer, a local oscillator, an IF amplifier, and a limiter amplifier.

When simultaneous two-way, narrow-band communication takes place (duplex operation), the two signal channels are passed through the wide-band amplifier and its limiter. They then modulate the transmitter and are transmitted with power levels approximately proportional to their received signal level.

 Command Subsystem

The command subsystem consists of receivers, decoders, and an antenna unit shared with the telemetry subsystem. The antennas consist of two pairs of whips connected through baluns to the two inputs of a hybrid. The two outputs of the hybrid correspond to the two polarization modes of the whips acting as a turnstile system. Each output is connected to a diplexer. Each diplexer provides 148-Mc command signals to a receiver and accepts 136-Mc telemetry transmission from a telemetry transmitter.

The two command receivers are identical, parallel units each with mixer, IF amplifier, and AM detector. The detector outputs of the two receivers provide audio output tones recovered from the modulation on the command transmission from the ground. Each command receiver is associated with one of the two redundant command decoders. Either receiver/decoder can exercise complete command control of the spacecraft.

Telemetry Subsystem

The telemetry subsystem consists of the antenna (shared with the command subsystem), two transmitters, each with its associated encoder, and the signal conversion elements. The 1.25- watt, 136-Mc transmitter is phase-modulated by a subcarrier which, in turn, is frequency- modulated by a time-division-multiplexed modulator that samples the amplitude of the various sensor signals. Certain critical control signals bypass the time-division-multiplexed modulator and are permitted to phase-modulate the telemetry transmitter directly.

Each transmitter and its associated encoder is one of a redundant pair, each pair operating at a unique frequency. Only one of the transmitter-encoder subsystems is permitted to function at one time, the power to the other subsystem being automatically turned off when the one is turned on. On command, encoder 2 may be disconnected, thereby removing the telemetry modulation and leaving the telemetry carrier to serve as a tracking beacon for the Minitracknetwork.

 Orbit Injection Propulsion

The Syncom orbit injection propulsion subsystem supplies the boost necessary to inject the spacecraft into a nominally synchronous, circular orbit after the vehicle has reached the apogee of a transfer orbit at the required altitude. The spacecraft is launched into the transfer orbit by the Thrust-Augmented Delta vehicle.

The propulsion subsystem consists of a single solid-propellant rocket motor. This motor is required to impart a velocity increment of 4696 fps to the spacecraft, which initially weighs 144.77 pounds.         The following parameters apply to this motor:

Specific impulse                       274.2 seconds

Propellant weight                     60.5 pounds

Case and nozzle weight          10.5 pounds

(including provision for attachment)

Motor weight                            71.0 pounds

Diameter                                  12.0 inches

Payload                                    75.8 pounds

The required performance and objectives given above are met by the JPL rocket engine designated the Starfinder.

Control Subsystem

The control subsystem consists of the components necessary to establish the desired longitude, to maintain a synchronous orbital velocity, and to orient the satellite spin axis from boost attitude to operating attitude. The subsystem consists of two pulsed-jet hydrogen peroxide propulsion units for velocity and orientation control, solar sensors, and control circuits.  An accelerometer for indicating firing is part of the control subsystem.

Electrical Power Subsystem

The electrical power subsystem consists of silicon solar cells, a nickel-cadmium battery, combined voltage regulators and switches. The subsystem is capable of supplying approximately 31 watts without drain on the battery when the satellite is not shadowed by the earth. The solar cells are arrayed on the external cylindrical surface. In the operating configuration, the sunline will be within 25 degrees of normal to the axis of the cylinder, a condition met by suitable choice of launch time.

Structure

The spacecraft structure includes a central, circular member with the separation flange for the Delta third stage at one end and attachment fittings for the apogee motor at the other end. A circularly symmetric bulkhead with reinforcing ribs on the separation side is attached to the member. The electronic units, gas tanks, and four solar cell panels are mounted to the bulkhead. The separation end of the central circular member carries the folding communication antenna. The whip antennas are attached at the apogee motor end of the solar cell panels.  Both ends are closed by thermal shields; the shield at the antenna end also serves as an antenna ground plane.Syncom 3V ASyncom 3V BSyncom 3V C