Voltage controlled oscillator with correction of tuning curve non-linearities

A scanning-superhetrodyne ESM receiver comprising:

• a stable combline source or harmonic oscillator for providing a stable reference signal, a frequency converting device, and a voltage controlled oscillator (VCO), and a frequency measurement device, said frequency converting device converting each stable reference signal component into an intermediate frequency using the voltage controlled as a local oscillator, and said frequency measurement device functions to provide a measure of said intermediate frequency;
• and wherein said stable reference signal provides
• a stable combline frequency source to generate a set of known voltage/frequency points, and
• processor means having a means for providing and storing values in a tempory memory is provided for employing the points as input to an interpolation program of said processor means to create the coefficients of a set of polynomial curves that together characterize the transfer curve of the voltage controlled oscillator, and
• wherein said processor means is used in a method used during operation for temperature compensating the transfer curve by providing a new set of polynominal coefficients periodically;
• and wherein
• the voltage controlled oscillator has a local oscillator frequency calculated using a known combline frequency of said combline or harmonic oscillator and a known intermediate frequency, and wherein there is provided processor means for calculating the value of the equation "local oscillator frequency value=the known combline frequency.+-.the known intermediate frequency", where addition of a known intermediate frequency is used if the combline frequency is below the value of the local oscillator frequency and the known intermediate frequency is subtracted if the combline frequency is above the local oscillator frequency.