SU448565A1 - Linear frequency modulated signal generator - Google Patents

Description

one

This invention relates to the field of radio engineering.

A linear frequency modulated signal generator, a high frequency generator, a jet element and a sawtooth voltage generator are known.

The aim of the invention is to increase the linearity of the frequency modulated signal.

This goal is achieved by introducing an adder, a delay line, a phase detector, a mixer, and an additional generator into it.

The block diagram of the generator is shown in the drawing.

The proposed device comprises a sawtooth voltage generator 1, an adder 2, a reactive element 3, a high frequency generator 4, a delay line 5, a mixer 6, a phase detector 7, a reference generator 8, a low frequency filter 9.

The generator works as follows.

The voltage produced by the sawtooth generator is fed through the adder to the reactive element. The reactive element changes the frequency of the high-frequency generator, the signal of which is fed to the single input of the mixer, and to the other input through a delay line. The voltage from the mixer output goes to the input of the phase detector, to the other input of which the voltage comes from the reference oscillator. The output voltage of the phase detector through the low-frequency filter is fed to the input of the adder.

Let us estimate the value 5 of the nonlinearity of the frequency change of the generator 4. You can write

| / e (0) - / e (P |

ten

6 z

where / e - frequency generator 8.

Since the frequency of the generator 8 has deviations, the value of which in the interval of formation of the saw is b /, the ratio can be brought to the form:

5: F,

20

This is relative to the instability of the generator 4. It is using only measures for

parametric stabilization is of the order that ensures the non-linearity of the change in the frequency of the generator 4 is not worse than 10, the linearity of the change in the frequency of the generator 4 does not depend on the change

transfer ratio of the reactive element.

Subject invention

A linear frequency modulated signal generator comprising a sawtooth generator, a high frequency generator to the input of which a reactive element is connected, characterized in that, in order to increase the linearity of the output frequency modulated signal, an adder, delay lines, a mixer, a low-pass filter and an additional generator, the adder being connected between the output of the saw-tooth generator and the reactive element, and the second input of the adder is connected via a low-pass filter to you phase detector, one of the inputs. Which is connected to the output of an additional generator, and the other - to the output of the mixer, the inputs of which are fed to the output of the high-frequency generator directly and through the delay line.