# Radar Doppler Multifunction
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{{Short description|Type of multimode aircraft radar}}
The '''RDM (Radar Doppler Multifunction)''', also known as the '''Cyrano 5''', is a French multimode [pulse-Doppler radar](/source/pulse-Doppler_radar) developed by [Thomson-CSF](/source/Thomson-CSF) (now Thales) for export variants and early French models of the [Mirage 2000](/source/Mirage_2000) [fighter aircraft](/source/fighter_aircraft). It is an evolution of the Cyrano IV installed on the [Mirage F-1](/source/Mirage_F-1) and in turn was developed into the '''RDI''' ('''Radar Doppler à Impulsions'''), a specialist air-to-air radar for French Mirage 2000 interceptors, and the multimode '''RDY''' ([Radar Doppler Multitarget](/source/Radar_Doppler_Multitarget)), which could track more targets at a time and added further air-to-ground modes.
==History==
The first prototype of the RDM flew in January 1980 and production deliveries began in early 1983.[{{cite news | title=RDM enters production for Mirage 2000 | url=http://www.flightglobal.com/pdfarchive/view/1983/1983%20-%200550.html | pages = 850–1 | newspaper=Flight International | date=2 April 1983}}] Thomson funded development of the RDM from the Cyrano IV at a cost of [FFr](/source/French_franc)350m (~US$50m); the RDI air intercept derivative was funded by the French government.[{{Citation | url=https://books.google.com/books?id=cxtFAQAAIAAJ&q=RDI | title=article | newspaper=Journal of Defense & Diplomacy | volume = 5 | year=1987 | page=62}}] The two radars are interchangeable in the aircraft but have little in common electronically; the biggest difference is that the RDI increases the [look-down/shoot-down](/source/look-down%2Fshoot-down) range in pulse doppler mode from {{convert|20|nmi|km}} to {{convert|50|nmi|km|abbr=on}},[{{cite journal | url=http://www.disam.dsca.mil/pubs/Vol%208-3/Anastassopulos%20%26%20Dussage.pdf | title=French 'Savoir-Faire' in Selling Arms: a New Way of Doing Business | first1=Jean-Pierre | last1=Anastassopoulos | first2=Pierre | last2=Dussage | journal = Long Range Planning: The International Journal of Strategic Management | volume=8:3 | pages=70–77 | date=Spring 1986 }}]
==Design==
RDM operates in the X-band with a coherent travelling-wave-tube transmitter and an inverted-[Cassegrain antenna](/source/Cassegrain_antenna) {{convert|655|mm|in|abbr=on}} in diameter.[ The RDM operates in air defence/air superiority, strike and air-to-sea modes. In the air-to-air role, the system can look up or down, range while searching, track-while-scan, provide continuous tracking, generate aiming signals for air combat and compute attack and firing envelopes. For the strike role it provides real-beam ground-mapping, navigation updating, contour-mapping, terrain-avoidance, blind let-down, air-to-ground ranging and Ground [Moving Target Indication](/source/Moving_target_indication) (GMTI).
In the maritime role it provides long-range search, track-while-scan and continuous tracking and can designate targets for active missiles. For air-to-air combat, the RDM provides a 120° cone of coverage, the antenna scanning at either 50 or 100°/s, with ±60, ±30 or ±15° scan. For air-to-air gun attacks, the 3.5° beam can be locked to the target at up to {{convert|19|km|nmi|abbr=on}} range, with automatic tracking within the [head-up display](/source/head-up_display) field of view, or in a 'super-search' area, or in a vertical search mode. Options include a Continuous Wave Illuminator (CWI) and Doppler Beam Sharpening (DBS). Comprehensive Electronic Counter-Countermeasures (ECCM) are incorporated.
The manufacturers claim that RDM will detect 90% of 5 m2 [RCS](/source/Radar_cross-section) fighter-sized targets out to {{convert|50|nmi|km|0|abbr=on}} in clear air using a four-bar search pattern over 120° in azimuth, and {{convert|60|nmi|km|0|abbr=on}} with a single-bar pattern over 30° in azimuth, dropping to {{convert|20|nmi|km|abbr=on}} in pulse-Doppler look-down mode.]