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Latest revision as of 09:28, 28 April 2025

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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 gavefor good resolution but weak signals (hard to detect distant objects) whilstwhereas long pulses gave strong signals but blurred resolution. With Barker coding you can transmit a longer pulse (strong) signal) 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>

His work also anticipated features of modern air traffic control systems, speech encryption and rotary encoders.

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.