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History of RADAR
During the post-war period, British radar research continued at institutions such as the [[Signals Research and Development Establishment]] (SRDE) and the [[Radar Research Establishment]] laterly known as the [[Royal Radar Establishment]] and [[Telecommunications Research Establishment]], Malvern. In 1953, an English physicist [[Ronald Hugh Barker]] was instrumental in the practical applications of [[pulse-code modulation]] (PCM), particularly in telemetry for guided weapons and early digital radar but most notably for the invention of the [[Barker code]] in 1953. Barker code is a binary sequence with ideal autocorrelation properties for minimising range side lobes in pulse compression radar and telemetry. In radar this means when you match the received signal against the transmitted code, you get a very clean, sharp spike showing target distance with minimal ghost echoes. Before the invention of Barker code, engineers had a tough trade-off between short pulses for good resolution but weak signals (hard to detect distant objects) whereas long pulses gave strong signals but blurred resolution. With Barker coding you can transmit a longer pulse but still decode it as if it were a short pulse to give sharp resolution. It allows better detection of small, fast, or closely spaced targets. Barker, R. H. (1953). “Group Synchronisation of Binary Digital Systems.” In ‘‘Communication Theory’’, edited by W. Jackson, London: Butterworths, pp. 273–287.
His work also anticipated features of modern air traffic control systems, speech encryption and rotary encoders.<ref>{{cite web |last1=Barker |first1=Ronald Hugh |title=Ronald Hugh Barker Research Paers and Publications (1938- 1976) |url=https://iet.adlibhosting.com/Details/archive/110069421 |website=Institute of Engineering and Technology |publisher=IET Archives |access-date=April 28, 2025 |ref=UK0108 NAEST 301/02}}</ref>
Barker’s work on data transmission paralleled and complemented earlier research by American engineers such as [[Alec Reeves]], who had first proposed PCM in 1937, and [[Claude Shannon]], whose theoretical advances after World War II laid the foundation for digital communications. Also, Alec Reeves, “Electric Signalling System,” UK patent GB538428A, filed 1937 and Shannon, Claude E. “A Mathematical Theory of Communication,” ‘‘Bell System Technical Journal’’, vol. 27, 1948.
PCM▼
His work on electrical pulse-code modulation systems<ref>{{cite patent| country=US|number=US2730676A|title= Electrical Pulse Code Modulation| url=<https://worldwide.espacenet.com/publicationDetails/originalDocument?FT=D&date=19530520&DB=&locale=en_EP&CC=GB&NR=691810A&KC=A&ND=4#|application-date=1951/ref> and digital transmission methods also contributed to early experiments in encrypted radar signals and the foundations of modern air traffic control systems.▼
▲PCM
Barker contributed specifically to practical PCM encoding techniques, reflected in his patents on electrical pulse-code modulation. Barker, Ronald H. ‘‘Electrical Pulse Code Modulation’’. UK patent GB662338A. Filed January 8, 1951. Published December 5, 1951. [https://worldwide.espacenet.com/patent/search/family/024884276/publication/GB662338A Available online].Barker, Ronald H. ‘‘Electrical Pulse Code Modulation’’. US patent US2730676A. Filed January 8, 1951. Issued January 10, 1956. [https://patents.google.com/patent/US2730676A/en Available online]. His later work also included developments in PCM encoder design for radar and telemetry systems.Barker, Ronald H. ‘‘Pulse Code Modulation Encoder’’. US patent US3721318A. Filed November 17, 1971. Issued March 20, 1973. [https://patents.google.com/patent/US3721318A/en Available online].
1952 Group Synchronising of Binary Digital Systems▼
1955 GB706687 (A) Electrical Signal Generating Systems IET▼
PCM
▲His work on electrical pulse-code modulation systems
▲1952 Group Synchronising of Binary Digital Systems
1948 Improvements in or relating to Apparatus for data in Binary Digital Form <ref>{{cite patent|country=US|number=US2730676A|title=Improvements in or relating to apparatus for the representation of data in a binary digital form |url=https://worldwide.espacenet.com/patent/search/family/010175782/publication/GB650913A?q=pn%3DGB650913A |publisher=European Patents Office |access-date=January 24, 2024 |ref=GB650913A |date=1951}}</ref>
1952 Group Synchronising of Binary Digital Systems
▲1955 GB706687 (A) Electrical Signal Generating Systems IET
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