This article first appeared in a slightly shorter form in the September 2005 Newsletter of the Narrow Bandwidth Television Association (NBTVA).
Synopsis: Although television and radar serve different purposes, there is a lot of overlap between the two technologies. We trace the history back to the early days and pose a challenge to the NBTVA.
It is 99 years since John Logie Baird (JLB) enrolled as a student of electrical engineering at the Glasgow and West of Scotland Technical College. In his memoirs he recalled that the knowledge gained in his first year "has remained with me all my life and has been of very great value". When he arrived in Hastings early in 1923 he was aware that different forms of electromagnetic radiation, of which visible light was only one, might be used to illuminate a person or object being televised. He soon discovered that infra-red radiation was almost as effective as light and this technique was christened "noctovision". He demonstrated it at the British Association meeting in Leeds in 1927.
While in Hastings JLB explored a third option, the use of very short radio waves to illuminate an object being televised. Very little can be found on it in the press or in scientific journals and it is not mentioned in JLB's own memoirs. Our main sources are patents and personal reminiscences. In JLB's British patent 292,185, the drawing from which is given as Figure 1, the means of illumination of the object is shown as a spark gap. This was a primitive device but in the early years of radio it had been the only practical means of transmission. JLB stated in his patent that the illumination came from that part of the spectrum consisting of very short radio waves, not much longer than infra red waves. It is significant that the object being televised is shown as a metal cross, rather than a human face as in JLB's conventional television patents. The human face would be a poor reflector of radio waves.
The system described in GB 292,185 (Figure 1) does not appear to provide the range of the object being televised, but if slight modifications are made to Figure 1 a primitive form of radar can be envisaged. The first change would be to move the object a long distance from the radio source of "illumination". The second would be to link the illumination source to the receiver, so that the transmitted and reflected signals can be shown on the same screen. This would enable the small time shift between the transmitted and reflected signals to be measured. (See below under "radio ranging".)
In May 1924 there appeared an article  by JLB about his early experiments in television and his final paragraph contained a glimpse of the future:
It is possible that at some future date means may be discovered of sending out energy from a point A, bringing it to bear on an object at a distant point B, and causing the object to radiate from its surface energy which, penetrating intermediate obstacles, can be brought to a focus at A, rendering it visible. This would be radio vision in a very different sense.
According to the recollections of the late Norman Loxdale, JLB used a battery-powered spark gap pulsed "radar" transmitter with a transmitting and receiving parabolic dish. Loxdale was a teenager in Hastings at the time and his recollections have been documented by McArthur and Waddell [3,4]. The receiver incorporated an insulated particle screen to retain the images of the pulsed echoes, a sort of a memory screen. An "improved memory screen" was the basis of another Baird patent GB 297,014 (March 1927) following GB292,185 (December 1926).
It has been suggested that Loxdale was a fantasist. However he had been interviewed well before the appearance of McArthur and Waddell's book  and he was not aware of Baird's patents GB 292,185 and GB 297,014. Nevertheless his description of Baird's equipment is consistent with the contents of the patents. Just prior to Loxdale's death in 1992, he was at the request of Dr.Waddell building a replica of the pulsed transmitter as used by JLB in 1923-4. Loxdale stated that the unit pulsed every 4 seconds. Such a pulse rate needs a memory screen to retain the echoes. Loxdale remembered that JLB was trying to detect reflections from the sky as well as echoes from objects on the cliffs, probably the cliff railway lines near Hastings. Loxdale was never told the full story behind this research but he always thought of Baird as being the first with radar in 1923-4.
As well as considering radio waves as a source of illumination for televised objects, JLB was using radio waves to carry television signals. He is reported to have been transmitting images along the south coast in April 1924 [5,6], but the question arises of where Baird got the transmitter from. On the balance of evidence it is considered that the transmitter was provided by J.J. Denton, a part-time physics lecturer and close friend, whose wife ran a boarding house in Hastings. Antony Kamm has kindly provided the authors with a copy of a letter written to the BBC in 1950 from a Mr. Pamment, who in 1923 stayed at the Denton boarding house. Denton had asked Pamment to go with him to his laboratory in London and see television images being sent and received at his laboratory but Pamment never took up the invitation. It was published at the time that Denton was undertaking secret radio research for the Government, but the writers are having problems in finding out exactly what Government work he was doing and in locating Denton's radio call sign for 1923-4.
The first formal report of the ability of a television signal to provide the range of signals reflected from an object was published in 1931 by Professor (later Sir) Edward Appleton. His main research interest was the ionosphere, but during 1931-32 he was also a part-time consultant to Baird Television Ltd., advising the company on the use of cathode-ray tubes (CRTs) and ultra-short waves. It was largely at Appleton's urging that the Baird company started experimental ultra-short wave television transmissions in April 1932.
Appleton noticed that a "ghost image" sometimes appeared on the signals received from the 30-line Baird transmissions which were being broadcast by the BBC from Brookmans Park. From a television point of view this was just a nuisance, but for Appleton it was a useful experimental tool. He concluded that the two images had arrived via two separate routes, 'direct' and 'reflected from the ionosphere'; the displacement distance between the two images on the screen related directly to the difference in the time of their arrival. It was therefore a simple process for Appleton to calculate how far the reflected signal had travelled from the object before reaching the screen (relating to the position of the ionosphere). The calculation was based on the number of picture elements between any identical feature on the 'direct' image and its counterpart on the reflected or 'ghost' image as shown in Figure 2 . Later in 1931 Appleton progressed to using a pulsed emitter and CRT receivers, in place of the transmitted TV signal and a Televisor, but the principle was the same . Fifty years later, the idea of television as a form of continuous-wave radar resurfaced in an article for children in a Christmas number of New Scientist .
Operational Radar and "Chain Home"
The detection of large objects by reflected radio waves was first documented in 1904 when Christian Hulsmeyer of Germany had used a spark gap pulsed transmitter to detect ships located several miles away, although he never managed to measure their range. By the early 1930s, much better results were being reported on the reflection of radio waves by moving objects, by organisations such as the U.S.Naval Research Laboratory in Washington and the Telefunken company in Germany [3,4]. These reports were buried in the patent literature and technical journals; they did not grab the attention of the general public in the same way as television. Nor were governments much interested in radar from an operational point of view, until 1935.
In that year, Britain was the first country to start developing radar operationally. A government committee on air defence, chaired by Sir Henry Tizard, recommended the development of what was then known as radio location. The project was given the code name Chain Home and it was led by Robert Watson Watt, a career civil servant who had worked on cathode ray tube direction-finding. Watson Watt had collaborated with Appleton in advising Baird Television Ltd. on cathode ray tubes in 1931. Appleton himself joined the Tizard committee in late 1936 and he was then briefed on the Chain Home project, of which he had no previous knowledge.
A wall of secrecy surrounded the Chain Home project and the radar research station at Bawdsey Manor, near Felixstowe, directed by Watson Watt. In September 1936, he used a modified EMI-Marconi television receiver as a pulsed 25 image per second radar receiver on the B.B.C. television wavelength of 7.6 metres, for the first national trials of pulsed radar. Here again was a use of television in ranging, although this time the receiver came not from Baird Television Ltd. but from their successful rivals in the competition to provide the BBC's first high-definition television service.
It is hard to pin down definite links between Baird Television Ltd. and the development of radar, but it is known that in the late 1930s one of the company's consultants was Professor F.A.Lindemann, who had served on Tizard's air defence committee and was Winston Churchill's scientific advisor.
Although the British public was unaware of radar, there were a few gaps in the wall of secrecy. In October 1936 the founder of the Luftwaffe, Erhard Milch, arrived in Britain on an official visit and alarmed his hosts by blandly asking them how their radiolocation project was coming along.[3,4] Two years later, at the time of the Munich crisis, the technical journal Television and Short Wave World published an editorial on "...a television system which could detect planes as far out as 200 miles" and further disclosing the British operating wavelengths for the system. Perhaps this was a deliberate release of information with government approval; equally, it may have been simply a security slip.
Radar goes public
Awareness of radar and its crucial role in World War II only reached the general public in 1945, as victory was achieved. Among the historical articles published at this time was one by R.L.Smith-Rose , head of the radio section in the National Physical Laboratory. He drew attention to Appleton's utilisation of CRTs  as being the basis of modern radar. This theme was not taken up by others and Appleton's name is just a footnote in the official radar histories, although his purely scientific work on the ionosphere was recognised when he received the Nobel prize in physics in 1947.
The name of Robert Watson Watt is firmly linked with radar in the public mind, not only as the leader of the operational team after 1935, but also as the inventor of radar. Watson Watt saw himself in this role when he appeared in 1951 before The Royal Commission on Awards to Inventors. He received a tax-free award of £52,000, worth about £2 million in today's terms, but considerably less than the amount he had claimed. Moreover the RAF controller of patents denied that Watson Watt was the inventor of radar; there was simply too much prior art in the area.
JLB had no public place in any of this. He had offered his services to the war effort in 1939, but no reply came  even though many former staff of Baird Television Ltd. were drawn into radar work. JLB spent the war years developing advanced systems of colour and stereoscopic television, at his own expense. In 1945, with his savings almost gone, he was busy starting a new television company for the post-war market. His diary for 1945 provides clues on his response to the radar disclosures. An entry on October 16 reads "secret patent radar" and a later entry reminds him to contact his patent agents for "radar renewals". In December an unsigned editorial in Wireless World  commented on the remarkable resemblance between patent GB 292,185 and the airborne radar system "H2S" which gave pilots images of the terrain they were flying over. The writer was probably the editor, N. Maybank, whose name appeared several times in JLB's diary at the time. It is open to speculation whether JLB would have gone on to press his claim in a more direct way, but he fell seriously ill in February 1946 and he died four months later, at the age of 57. For the next 25 years his reputation declined while a concerted effort was made to publicise the Marconi-EMI company's development of electronic television.
Meanwhile a US Patent (R.H. Rines, US 2,696,522) for a scanned radar with an insulated particle screen had appeared in 1954 almost unnoticed. At the head of the list of prior art was Baird's 1930 US patent 1,699,270, the technical equivalent of GB 292,185. In his US patent, JLB had described the system as "extremely valuable in case the invention is used during a war, for instance, where it is desired to view the enemy's position without detection." Although the resolution of images deteriorates when reflected radio waves are used instead of light, the range of radio waves is far greater than that of light. Baird's radio wave version of the "noctovisor" in the mid-1920s, therefore, had great potential as a defense system. From this, it can be argued that GB 292,185 could not operate with the same resolution as early television but rather it was designed as a form of radar.
Controversy—and a challenge to NBTVA
It was not until the mid-1970s that the overlap between JLB's experiments and radar became generally known, through the researches of Dr.Peter Waddell. In 1979 Professor Russell Burns(13) described GB 292,185 as a "rudimentary form of radar". In 1986 McArthur and Waddell published their biography of JLB  and in 1990 they brought out a sequel  with new data pointing to definite links between JLB and radar. In the late 1990s Adrian Hills produced several publications and a CD under the auspices of the University of Strathclyde, linking JLB with radar . However in 2000 a technical biography of JLB by Burns  flatly denied that JLB's work had anything to do with radar. In 2002 a further biography by Kamm and Baird  took the middle ground and tried to point out, for the non-technical readers, the areas of overlap between the two technologies. Within the past 3 years a series of articles in Transmission Lines, by Peter Waddell and Brandon Inglis, has presented new information some of which has been included in this short overview.
Although much historical work has been done and more is in progress, the controversy about the connections (or lack of them) between early television and early radar is unresolved. It is strange that no one since Appleton appears to have made any experimental observations in this area. Here is a challenge for NBTVA members who have unique practical expertise in JLB's early technology. The challenge is to reconstruct equipment as close as possible to the specifications in JLB's early patents and then evaluate it in terms of range, quality of images, etc.
The authors will be happy to answer questions of detail and provide copies of any of the cited papers or patents for NBTVA members who are seriously interested in taking up this challenge.
1. Baird, J.L., Television and Me, Mercat Press, Edinburgh, 2004 (first drafted by JLB in 1941)
2. Baird, J.L., An Account of some Experiments in Television, The Wireless World and Radio Review, pp.153-155, May 7, 1924
3. McArthur, T. and Waddell, P., The Secret Life of John Logie Baird, Century Hutchinson, 1986
4. McArthur, T. and Waddell. P, Vision Warrior, Scottish Falcon Books, Orkney Press 1990
5. Kamm, A. and Baird, M.H.I., John Logie Baird: a life, National Museums of Scotland Publishing, 2002
6. Press Assoc. London News Agency, 9 April, 1924, Glasgow Evening News. Also Cinema Shows by Wireless, Thursday, 10 April, 1924, also Glasgow Herald, Pictures by Wireless, Thursday, 10 April, 1924
7. Appleton, E. V. The Timing of Wireless Echoes, the use of television and picture transmission, Wireless World, 14 , January, 1931, pp.43-44
8. Appleton, E. V. and Builder, G., A simple method of measuring Wireless Echoes of short delay, Nature, 127, 1931, p.970, see also Proc. Phys. Soc, 44, 1932, pp.76-87
9. Hunkin, T., How to use your TV as Radar, New Scientist, 112, 25 December 1986 - 1 Jan 1987, p.49
10. Editorial, Television and Aircraft Detection, Television and Short Wave World, September 1938
11. Smith-Rose, R. L. Radiolocation 2, History of its development, Wireless World, March 1945, p.68
12. Editorial, Radar Prehistory. Wireless World, December 1945, p.357.
13. Burns, R., J.L.Baird: success and failure, Proc.IEE, 126, 921-928 (1979)
14. Hills, A. R., Visions: the Life and Legacy of John Logie Baird (CD), SCRAN, University of Strathclyde, November 1999
15. Burns, R., John Logie Baird, television pioneer, IEE history of technology series, No. 28, 2000, p.119
About the authors
Malcolm Baird is the son of J.L. Baird and is hon. president of NBTVA. He has lived in Canada since 1967 and is a retired professor of chemical engineering.
Douglas Brown is the Director of the Science and Technology Forum, University of Strathclyde, Glasgow. He holds an MPhil and PhD for research on J.L. Baird and Baird Television.
Peter Waddell is a retired reader in mechanical engineering at the University of Strathclyde. As a hobby since 1973, he has studied the life of J.L. Baird and he is co-author of two biographies.