Method for processing video signals in a digital image transformer
AssigneeThomson-CSF
InventorsChristian Lachaize, Jean-Pierre Andrieu, Christian Chagny
Life of this patent
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Abstract
A method for processing video signals in a digital image transformer in which, before conversion of the video data of the radar from polar coordinates into cartesian coordinates to be displayed on a television monitor, the distance sampling frequency is phase-locked to the sync pulses of the radar and the number of converted radials is limited to the resolution of the coder while satisfactory persistance is ensured and conversion errors are eliminated.
Claims8
In a digital image transformer having an oscillator for generating a sampling frequency in response to sync pulses from a radar and a coder for receiving from an antenna a radar scan of a target video signals represented by polar coordinates, a method of converting the video signals from polar coordinates into cartesian coordinates, the method comprising:
- phase locking the sampling frequency to the sync pulses for carrying out distance sampling of the video signals, the sampling frequency being fixed, whereby distance errors made by the radar in determining the distance of the target are eliminated;
- and
- triggering the plotting of the video signals, the triggering being initiated by the sync pulses and the video signals being representative of the values of the rotational angles of the antenna detected at the time of emission of the sync pulses;
- whereby the polar coordinates representing the video signals are converted into corresponding cartesian coordinates for display.
In a radar including a digital image transformer and an antenna for intercepting video data in the form of polar coordinates during a radar scan of a target, the radar further generating therein sync pulses and measuring angle of rotation data from the antenna, an apparatus for processing the received video data from polar coordinates into cartesian coordinates, the apparatus comprising:
- a coder for receiving the video data from each radar scan, the coder converting the video data from an analog format to a digital format;
- an oscillator, connected to the coder, for receiving the sync pulses generated by the radar and for outputting a sampling frequency phase locked to the sync pulses to the coder, the video data received by the coder being quantified by the phase-locked sampling frequency;
- an operator connected to the coder for receiving therefrom the quantified video data;
- a memory means connected to the operator for storing therein the quantified video data for each scan received from the operator;
- and
- a processor means, connected to the operator for the control thereof, having as inputs the angle of rotation data of the antenna, the sync pulses generated by the radar and the stored video data of the preceding radar scan from the memory means, for converting the video data of the preceding radar scan from polar coordinates into cartesian coordinates, the video data being represented by an angle of rotation value defined at the time of emission of a corresponding sync pulse;
- whereby the received video data is displayed as cartesian coordinates.
Dependencies are inferred from the claim text.