Engineers Walk

Ralph Benjamin Plaque

Ralph Benjamin (1922- )

Ralph Benjamin was born in Darmstadt, Germany in 1922, where he enjoyed a classical education, and physical activities, both indoor and outdoor. At the age of 14 his parents sent him to a boarding school in Switzerland, to protect him from increasing Nazi persecution. The lessons were in English, and they studied for the Oxford School Certificate examinations taken locally. After 6 months the Nazis blocked funding from Germany, and the young Benjamin was obliged to leave the school and take refuge in a Spartan refugee camp. In the face of this adversity he continued to study alone, in the foreign tongue, and passed the examination with the highest grades of anyone in the local examination centre. Ralph Benjamin's parents were murdered in Auschwitz.
With meagre support from an older brother living in the USA he made his way to London in March 1939 to live with an Aunt. He won a scholarship to St Oswald's College, Ellesmere and, turning from classical to science subjects, he passed the Higher School Certificate in just one year. He then worked as an electrician's mate, doing first menial work and later skilled work in a factory building Blenheim bombers. He was fortunate to meet a benefactor who undertook to support him and in 1941 he started an accelerated degree course at Imperial College. Over the three years the course moved from science to engineering, on to electrical engineering and finally to communications. On the way he invented the single-sideband mixer.

Although the final exams were interrupted by flying bombs Benjamin got a first and, in 1944, joined the Royal Navy Science Service as a temporary Experimental Officer in the Admiralty Signals Establishment (ASE) at Witley in Surrey. His first works were on ship borne radars to detect enemy submarines, and then on periscope radars for our own submarines. As part of an Anglo-American team to develop an IFF (Identification Friend or Foe) system, he designed and built a simulator of a mass air attacks on a naval task forces, developing appropriate new techniques and components.

Admiralty Surface Weapons Establishment (ASWE)

At the end of World War II in 1945, Benjamin chose to stay with the Royal Navy as a Scientific Officer. He became a British Citizen and has given loyal service in his professional life to the defence of his adopted country and indeed to the Western Alliance. Radar development and communications merged with gunnery, guided weapons and a range of other technical matters to become the Admiralty Surface Weapons Establishment, ASWE, at Portsmouth.

Radar (Radio distance and rangefinder), which was still secret, works by emitting radio pulses from a rotating antenna. When a pulse hits a target, some of the radiation is reflected as an echo. The bearing of the antenna when a reflected signal is received is the bearing of the target, and the time delay of the echo indicates the distance to the target. The results were usually displayed on a circular screen, with a rotating radial line synchronised to the rotating antenna, and with a bright spot indicating the target. Detection required direct line of sight from the antenna to the target, and the range was limited. Capital ships like aircraft carriers had therefore to be protected by stationing smaller more expendable ships (e.g. destroyers), known as radar pickets, around them. Transmission of the pickets- radar was ruled out, partly because alignment of the directional antennas for microwave links between moving ships would have been difficult, but primarily because the line of sight range for the link would have been much too restrictive. Hence pickets could only give crude verbal warning that a raid was on the way.

ASWE Benjamin realised that the essential information required by the capital ship was the location of targets defined by their X,Y grid coordinates, which could be transmitted from the pickets over long distances by radio, and that the X and Y co-ordinates could be extracted by a "roller ball" controller, now known as the "computer mouse". Indeed, the cursor spot, controlled by the mouse, could provide a more general two-way interface between the visual display and the corresponding digital data system.

There followed an intensely creative period, which led to the birth of Force-Wide Integrated Command and Control Systems, now used world-wide on land, sea and air, for both military Tactical Control and civil traffic control. To implement this Benjamin developed two main systems,

Comprehensive Display System., CDS. On the capital ship's and pickets' radar screens, a marker was placed over the target echoes using a joystick or mouse. The grid coordinates of the target could then be derived from the marker position. Successive plots of a target's position could be used to predict the target's speed and direction, and the operator only needed to establish new markers occasionally to check that the predictions were correct. The marker of each target was further associated with digital information indicating its height, identity, status etc., so that they could be displayed with identifying symbols, and/or selectively as desired by the user. A friendly weapon system (fighter, gun or missile) could be assigned to each foe target and guided to it. A further refinement was to evaluate the threat posed by each foe, and prioritise the nearest and most appropriate weapon to destroy each foe. The markers also provided a link to a subsidiary display giving other relevant information, or from a digitally selected track number to its plan-position display. Even in the early days jamming radars had been developed which obscured real targets and/or set up false (or ghost) targets. CDS was also used to identify the bearings of the jammers and, with bearings from a number of pickets, the jammers could become foe targets themselves.

Digital Plot Transmission, DPT. The resultant locations of all the targets, seen by any of the ships in the force, were made available to all via DPT, the world's first digital data net. This involved offsets for the different (and changing) relative locations of the radar ships, and provision for sharing reporting responsibilities between ships, whilst avoiding gaps or duplicate reporting of the same target.

Benjamin made these systems very reliable by introducing high redundancy, and reduced downtime by separating the electronics into modules, with pre-planned diagnostics facilitating fault location and rapid replacement of modules. He also developed simulators so that operator training could be carried out in parallel with system development.

Mural There were frequent exchanges of information with the US Navy, generally to the benefit of both parties. On his first visit to the USA in 1946 Benjamin revealed his Digital Plot Transmission and Comprehensive Display which aroused great interest because it was well in advance of anything the Americans were doing at the time. The Royal Navy was perhaps a little naive in not patenting many of Benjamin's inventions, whereas the US Navy was sometimes reluctant to reveal information it regarded as commercially sensitive. Despite many invitations Benjamin never accepted a permanent post in North America. However in 1956 he was the only non American invited to join a short term project, involving all of the US forces, to devise the air defence of the North American continent.

In addition to working hard in his professional life, Benjamin played hard in his private life. There was skiing (learned in Switzerland), and boxing (at Imperial College), rugby, and judo, where he became a black belt and represented first Dorset and later Gloucestershire, and he had developed an interest in climbing and led a number of Alpine Expeditions, including one first ascent. It was on one trip to the Austrian Tyrol that he met Kathleen Bull who became his wife in 1951, but their happy partnership had to overcome many misfortunes. Each of their two sons John and Michael, was born only after three miscarriages, and there were serious illnesses for Benjamin and the children. Sadly, as a young adult, John was killed in a skiing accident and the other party involved was convicted of manslaughter.

Benjamin achieved rapid promotion and gradually had to assume management of engineering projects, and he developed clear ideas of best practice for successful results. A project leader must be a champion for the project and able technically to understand all aspects. 'Temporal' changes are inefficient, so it is better for the project team to see the project through applied research, manufacture, operation, and support with handbooks and spares lists. 'Parallel' development interfaces are also inefficient and a small team of top class people is best. The leader should take on day to day administration, but where this is not possible he should have a partner to take on this role.

There were many other projects in which Benjamin had a hand including,
  • 3-Dimensional Radar (type 948) - a vertical stack of scanning narrow 'pencil' beams.
  • Radio Finger Printing - of unique differences from nominally identical transmitters
  • Carrier Controlled Approach - to minimise landing times
  • 4.5mm Mark 8 Gun - for use where a guided missile would have been expensive overkill.
  • Mobile Satellite Communication - requiring stabilised antenna
Benjamin's final post at ASWE was Head of Research and Project Studies. He had served on many committees for the Ministry of Defence and joint committees with academics, US services, Commonwealth partners, and NATO allies. In the book 'Cold War, Hot Science', a study of UK defence research from 1945 to 1990, the authors conclude 'Ralph Benjamin and his colleagues were responsible for some of the fundamental technologies of the second half of the 20th century'.

Admiralty Underwater Weapons Establishment (AUWE)

Torpedo - Fore
Torpedo - Midships
Torpedo - Aft
In 1964 Benjamin was appointed Chief Scientist and Director of the recently formed Establishment which had a staff of 2,500 mostly centralised in Portland. This combined torpedoes, underwater detection (sonar), mining and countermining, and diving, all formerly undertaken at separate establishments. Benjamin applied his principles of project control and management to get the legacy departments working together harmoniously and managed rapid progress in all these fields.

To support R&D on diving and diving in support of other R&D, he also qualified and practised as an RN Diving Officer.
Some essential features of torpedoes are
  1. Mechanical strength to avoid buckling
  2. No reliance on atmospheric oxygen for propulsion
  3. No exhaust gases that might enable detection
  4. Optimum homing using torpedo acquired data and ship data passed by wire
  5. Silent launching
Sonar is the acoustic equivalent of radar, but with greater complications. Sound pressures are of the same order as the water pressure. Variations of water pressure due to waves, currents, salinity and temperature will affect the transmission of the sound waves. Sound speed is slow, and the ship will have moved by the time it receives a reflected wave. Helicopter-borne sonars, dropped into the sea on a cable, were effective. However in recovery the sonar will swing forward as it breaks the surface, and oscillations become more violent as the cable is wound in, creating a danger to the helicopter.

Mines moored to the sea bottom could no longer be cleared by a sweep wire because of a clever device in the mooring cable which allowed the sweep wire to pass through without detonating the mine, and in any case mines are increasingly laid on the sea bottom. Mine clearance came to depend on simulating the magnetic, acoustic and pressure 'signatures' of a passing ship to actuate the fuses of a mine. The ships that towed the simulating devices had many design features to reduce their own magnetic, acoustic and pressure 'signatures'. Mine design then advanced to evade these countermeasures by randomising the reaction of the fuses to the simulations. A nominally 'cleared' area could not be guaranteed to be clear of mines, and this led to the development of ultra high-resolution sonar for "mine hunting" ships.

Government Communications Headquarters (GCHQ)

In 1971 Benjamin was appointed Superintendent Director at GCHQ in Cheltenham. The primary function of the establishment is to gather Signals Intelligence which can be divided into,
  1. Electronic Intelligence (ELINT) which gathers and analyses the electronic signals from the radar and weapon control and guidance systems of potential (or actual) enemies. The strength and deployment of their forces can be assessed, and any weaknesses can be identified for possible exploitation.
  2. Communications Intelligence (COMINT) which analyses who is communicating with whom, their locations and the varying patterns of the traffic. If coded or encrypted communications can be decoded or unscrambled, this gives a clear view of enemy intentions which is vital in wartime.
Another function of the establishment is Communication Security (COMSEC) by which our own communications are protected from interception or jamming. Benjamin's nominal role was research and development in Signals Intelligence however he was required to take on a range of other tasks,
  • R&D for Communications security
  • R&D for Computer Security
  • Development of special purpose computers
  • Professional supervision of code breakers
  • Application of scientific methods to intelligence analysis
  • Analysis of intelligence on scientific subjects
  • Career management of al scientific and technical staff
    And later,
  • Management of all technical equipment development, procurement and operation,
  • Computer programming
  • Operation and development of GCHQ's own communications
GCHQ is part of the Foreign Office, and Benjamin also took the role of Head of the Scientific and Engineering Profession for the FO as a whole. He also took on the part-time roles of Chief Scientific Advisor to the Director General of the Security Service and to the Chief of the Secret Intelligence Service and, on behalf of the Cabinet Office, the co-ordination of the R&D Programmes of all the Intelligence Services.

Just as in his Navy days, he served on many Government committees and joint committees with US services, Commonwealth partners, and NATO allies at the highest level, often involving foreign travel. He also gave briefings to senior politicians including the Prime Minister Mrs Thatcher.

The acknowledgements of Benjamin's technical achievements from all sides when he retired from GCHQ make it clear that there were considerable technical innovations. However his work with GCHQ is covered by the Official Secrets Acts and has never been revealed. One insight is the development of a speech security system that was sufficiently robust for use on a wide variety of mixed quality commercial channels. This was adopted by Mrs Thatcher and President Reagan for communications between them and to others. Another achievement was a very much cheaper and lightweight encryption system for use during the troubles in Northern Ireland. This was later adopted by many of the United Kingdom Police Forces.

North Atlantic Treaty Organisation (NATO) Benjamin retired from Government service in 1982 on reaching the age of 60, but he had so much energy and ability to give. Although there were plenty of well paid opportunities in British and Foreign industry his personal ethic, as an ex Government employee with a wealth of inside knowledge, stopped him taking that path. He accepted an appointment as Head of Communications Techniques at Supreme Headquarters Allied Powers Europe (SHAPE) Technical Centre. The job was in The Hague in The Netherlands, but he always intended to return to the UK and first established a home in Bristol.

The NATO communications system he found had obsolete exchanges, which did not match the new circuits. Commercial estimates of the time and cost of modifying the exchanges were very high with no guarantee of success. Benjamin designed and built, in house, microprocessor-based interface boxes which were installed between the circuits and exchanges at much lower cost in money and time.

The communications system was at the heart of NATO's Command and Control System in the event of war. To inspire the confidence of Military Commanders, he developed a computer based tool for emergency reconfiguring of the system if damaged in war. In addition he encouraged users to reduce their reliance on the system by more delegation, by orders to implement pre-prepared contingency plans and by only requiring reports to commanders about unexpected developments.

Benjamin advocated more efficient routing of communications. A satellite link could send a communication over a vast distance without it travelling through intermediate nodes. As terrestrial links (cables and fibre optics) are less vulnerable to interception - or mutual interference - than radio links, he advocated that radio links should preferably only be used to link mobile users to the nearest node of the static communications network.. He suggested that the hierarchy of exchanges could be reduced to just two layers, because of the falling relative costs of fibre optic links compared to exchanges. He also conceived the term 'virtual ether' to describe a system where any user could be connected to any other user with as much capacity and time as required.

Life in Bristol

Professor Benjamin and Michel Clinch In 1987 at the age of 65 Benjamin 'retired' again and came back to the UK to his home in Bristol. Part of his philosophy for a fulfilling life is to make your life's work your principal hobby, without excluding other hobbies. Engineering, including the analysis of systems, has given him a creative and satisfying principal hobby. He derives particular pleasure by finding a solution to a problem, often by lateral thinking, when others have said it is impossible.

With this philosophy he is never going to retire. He has been a visiting professor at Imperial College, the Open University and the Military College of Science and played a very full role in the Defence Scientific Advisory Council. He is still is a very active as visiting professor and University College, London and, particularly, at Bristol University, and a consultant to Industry. With his technical expertise and long experience of managing engineering projects he has inspired some important new work. In his lecture to the Retired Professional Engineers' Club (Bristol) in 2006 he spoke about the following,
  1. Smart Mobile Base Stations and Dumb Terminals. This is a method of transferring processing from many sparsely used mobiles to an intensively used common base station, thus saving the complexity, bulk, weight, power consumption and cost in all the mobiles.
  2. Low radiation CAT body scanners. By using object based 3-D X-ray imaging, dramatic reduction of radiation dosage, data processing and cost can be achieved.
  3. Finding Explosives in Aircraft Luggage. Object based 3-D imaging gives a much improved determination of the density of objects scanned.
  4. Detection of 'invisible' buried land-mines. The mine is detected by Real Aperture Synthetically Organised Radar (RASOR) from an array of antennas.
  5. Detecting 'undetectable' Tumours. RASOR scans can detect small cancerous breast tumours that cannot be seen by X-rays.
Ralph Benjamin is still working hard and continues to enjoy strenuous walks with his wife.

John Coneybeare (February 2011)


  1. Five Lives in One by Professor R Benjamin CB - published by Parapress
  2. Oral History - Ralph Benjamin : an interview by Peter C J Hill - No 465 for the IEEE History Center, The Institute of Elecrical and Electronic Engineers, Inc.
  3. 'Cold War, Hot Science' , a study of UK defence research from 1945 to 1990, sponsored by the Science Museum and the Ministry of Defence
  4. Notes taken at lectures by Professor Benjamin - Mr E Moss and Mr A Smith

    Authors Note

    It has been my privilege to be acquainted with Ralph Benjamin and his charming wife Kathleen, through our common membership of the Retired Professional Engineers' Club (Bristol). I think the secret of his success has been his willingness to work hard and think hard. Ralph is a quiet man with a wonderfully robust sense of humour and is very patient with journeyman engineers like me. In addition to his occasional lectures to the club, he can always elicit an interesting discussion with a visiting speaker if the question session is flagging - a great comfort for the chairman of the meeting!