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Direct digital FM waveform generator for radar systems

  • US 5,151,661 A
  • Filed: 08/26/1991
  • Issued: 09/29/1992
  • Est. Priority Date: 08/26/1991
  • Status: Expired due to Fees
First Claim
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1. A linear FM waveform generator employing direct digital synthesis, said generator comprising:

  • clock means for generating system clock signals at a predetermined frequency;

    means driven by said system clock signals for generating a linear digital FM signal;

    means clocked by said clock means for converting said linear digital FM signal to a linear analog FM waveform;

    sampler means clocked by said clock means for sampling said linear analog FM waveform to generate a sampler linear analog FM waveform that can be directly employed for generation of an output linear FM waveform;

    means for filtering said sampler linear analog FM waveform; and

    means for multiplying said filtered sampler linear analog FM waveform to generate an output linear FM waveform,wherein said linear digital FM signal generating means includes a first register generating a constant value representing the slope of the linear FM waveform, a first integration stage having a second register and a first adder coupled to the output of said first register, said second register generating a digital output representing frequency as a function of time, a second integration stage having a third register and a second adder coupled to the output of said second register, said third register generating a digital output representing phase as a function of the square of time, and means for generating in response to the digital output from said third register a digital signal representing amplitude as a function of time and corresponding to said linear digital FM waveform that is coupled to said converting means for conversion to an analog waveform.

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