ASVX (PARTS 1 AND 2) [Main Title]

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  • Title: ASVX (PARTS 1 AND 2) [Main Title]
  • Film Number: AMY 200
  • Other titles:
  • Summary: A very technical training film for the ASVX anti submarine radar fitted to Fairey Swordfish aircraft. The first part examines each electronic component using animated diagrams and close up photography to explain their function. The interrelation between these units that combine to form the ASVX radar is explained in extensive diagrams with a clear and precise narrative. The second part depicts the ASVX in operation during a Swordfish sea patrol.
  • Description: PART ONE - BASIC PRINCIPLES: Reel one: Film opens with Swordfish in flight with the rotating ASVX antennae housed in a nacelle below the fuselage, used to locate submarines from the air, day or night, inclement weather or beyond visible range. Other uses include ship location, navigation by coastal charting, making landfalls, navigation by homing on long range radar beacons and landing in co-operation with blind approach systems. Film cuts to radar operator in the rear seat of a Swordfish aircraft operating the combined receiver/transmitter who is observing the returned radar pulses on a circular cathode ray tube display (CRT). Calm seas will reflect most of the transmitted pulse away, but a ship or rough sea will scatter the pulse and send some of the radar pulse back for display on the CRT. “Display”: Three different types of presentation are used: Plan position indicator (PPI), Range – azimuth, Left – right range. All are displayed on a circular CRT engraved with a graticule of various measurement scales. The PPI system is described in a series of composite animated diagrams showing the transmitted pulse and the returned pulse that appears as a blip on the rotating time base of the CRT. This rotating time base is synchronised with the rotating antennae from which the range and distance to the reflecting object are determined. Thus a plan view beneath, and all around the aircraft, is built up. The range–azimuth presentation differs in that the time base is vertical, and moves across the CRT in response to the rotating antennae, providing more accurate bearing and range values at close distances. Reel two: The left–right presentation does not use the scanner. A separate RX/TX operates on a different frequency and uses separate antennae fixed to the upper and lower surfaces of the port and starboard wings. Beams (or pulses) are projected ahead of the flight line, sweeping areas both to port and starboard. The display appears as a vertical, stationary time base with sideways deflections to port and starboard from the reflected pulses. “Scanning”: The beam is tilted at shallow angles by means of a mirror in the rotating antenna. The antenna makes one revolution for each of the four positions of the tilting mirror, the composite scan presented on the PPI display. Another extensive series of animated diagrams provide for greater clarity. “Sea returns”: Rough sea will return some of the signal and present a bright spot at centre of the PPI display, the brightness varying with sea roughness and aircraft height. PART TWO - OPERATION OF CONTROLS: Reel three: "Measurement of range and bearing”: The circular CRT indicator is used for all three types of display. The range of the target is read from five calibrated, concentric circles engraved on the screen. Target bearing is read from a graduated scale around the circumference of the screen. The upward presentation of the display always indicates the direction of the aircraft. The use of the seven range selector switch is described and illustrated in detail. Apart from rotating as normal, the scanner (i.e. the rotating antenna) can be made to oscillate when scanning ahead of the flight line. The dimensions of the area to be scanned may be determined by the range switch in conjunction with other associated controls. Further examination of these controls and their effect is given. “Gain and brilliance control”: These controls enable the operator to adjust the display to suit the ambient conditions, and personal preferences, thus maximising the information he can read from the display. “Reduction of sea returns”: The effect of sea returns has been demonstrated above, and may conceal a target within the bright spot. Use of the sea return differentiator – filter unit type 164 – will break up the sea returns to reveal the target echo. Reel four: “Tuning”:Tuning is normally carried out on the ten mile time base. The Lucero transmitter generates energy transmitted and received by the wing mounted antennae. Film shows Swordfish on the ground, focusing on the tuning controls, as the narrator explains their operation, using the stationary range presentation on the VDU. The clearest signal is not necessarily the one with the greatest amplitude, cleanliness is more important than size. Alternative tuning techniques are examined, the choice dependant upon the type of echo received, land returns are used in preference. Finally, the swordfish remains on the ground, and the film shows how the ASUX is used operationally. Fitted into the two seat aircraft, the various components of the ASVX system are arranged as follows: Generator, VCP, power pack, modulator, junction box, indicator unit, sea returns differentiator, oscillation unit, control unit, another modulator, HF unit, amplifier and Lucero box. The observer climbs into his very cramped cockpit and begins to set up the equipment. The process is lengthy but logical, with excellent photography and narrative that explains all. After completion the Swordfish takes off for a sortie. Upon return, certain controls are fine tuned before landing.
  • Alternative Title:
  • Colour: B&W
  • Digitised:
  • Object_Number: AMY 200
  • Sound: Sound
  • Access Conditions:
  • Featured Period: 1939-1945
  • Production Date: 1943
  • Production Country: GB
  • Production Details: AIR MINISTRY (Production sponsor) Telecommunications Research Establishment (Production sponsor)
  • Personalities, Units and Organisations:
  • Keywords:
  • Physical Characteristics: Colour format: B&W Sound format: Sound Soundtrack language: English Title language: English Subtitle language: None
  • Technical Details: Format: 35mm Number of items/reels/tapes: 4 Footage: 3383ft
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  • Link to IWM Collections page:

    AMY 200

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