SU1711318A1 - Frequency-swept oscillator - Google Patents

Abstract

The invention relates to radio engineering and can be used to linearly vary the frequency over a wide range. The purpose of the invention is to increase the linearity of the change in the frequency of the output signal at: the beginning of the tuning cycle. The generator contains a frequency detector (BH) 1, a tunable generator (PG) 2, an adder 3, a saw-tooth generator (GPN) 4, an integration block 5, a differentiation block 6, a tuning rate setting block 7, a subtracting amplifier 8, a threshold element 9 and key 10. The sawtooth voltage from the output of the FPG 4 through the adder 3 is fed to the input of PG 2, the frequency of which under its influence begins to change in the specified Frequency Range. The frequency change of the PG 2 using FB 1 is converted into the corresponding voltage that differentiates unit 6. At the output of block 6, a voltage is generated, determined at each moment of time by the rate of change of the frequency of PG 2. This voltage is applied to the inverting input of the subtractive amplifier 8, to the direct input of which voltage is supplied from the output of block 7 corresponding to the rate of increase of the sawtooth. The voltage from the output of the detracting amplifier 8 through the switch 10 and the integration unit 5 is fed to another input of the adder 3, due to which the control voltage is corrected, which increases the linearity of the frequency change. 2 Il.

Description

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The invention relates to radio engineering and can be used to linearly vary the frequency over a wide range.

The purpose of the invention is to increase the linearity of the change in the frequency of the output signal at the beginning of a tuning cycle.

Fig. 1 shows a structural electrical circuit of a oscillating frequency generator; Fig. 2 shows timing diagrams explaining the operation of the oscillating frequency generator.

The oscillating frequency generator (Fig. 1) contains a frequency detector (BH) 1, a tunable generator (PG) 2, an adder 3, a sawtooth voltage generator 4 (HPF), an integrating unit 5, a differentiation unit b, a tuning rate setting unit 7, subtracting the amplifier 8, the threshold element 9 and the key 10.

The oscillating frequency generator operates as follows.

In the initial state, in the absence of voltage Ui (Fig. 2a, t 0) at the output of the FPG 4, the voltage Uy at the input of PG 2 is zero (Fig. 2b, t 0), with the result that the frequency of the signal at its output is fn ( figv, t 0). At the same time, the voltage U2 at the output of BH 1 paprio is zero (fig.2g, t0), as a result of which the voltage W at the output of differentiation unit 6 is zero (fig.2d, t0). The voltage Uz is fed to the input of the threshold element 9, which remains at the same time in the initial state O, and the zero goes to the inverting input of the subtracting amplifier B, the direct input of which receives a constant voltage W from the output of block 7, which corresponds to the rate of increase of the sawtooth voltage Ui. In this case, the output of the subtracting amplifier 8 produces a voltage Us (FIG. 2e, t 0), which is fed to the signal input of the switch 10. However, since the voltage Ue at the direct output of the threshold element 9 corresponds to a logical zero (FIG. 2g, t 0), then the key 10 is closed, as a result of which the voltage Us does not pass through it.

From the output of the FPG 4, through the adder 3, the sawtooth voltage Ut enters the input of PG 2 (Fig. 2a, t ti ... t2), under the action of which the frequency of PG 2 begins to increase (Fig. 2b, t - ti .-. Ta) at a rate determined by the modulation characteristic of PG 2 and the rate of increase of the control voltage.

Changing the frequency of PG 2 with BH 1 is converted to the corresponding voltage W (Fig. 2d, t ti ... t2). Voltage U2 goes to differentiation unit 6, at the output of which voltage is generated from (fig. 2d, t - ti ... t2). defined in

each moment of time by the rate of change of the frequency of PG 2. At a positive voltage from 0, the output U of the threshold element 9 produces a voltage Ue,

corresponding to logical 1 (fig.2zh, t ti .-. ta). which opens the key 10. At the same time in the subtracting amplifier 8, to the inverting input of which a constant voltage U4 is applied, corresponding to

a given slew rate Ui is set, the real frequency tuning frequency of PG 2 is compared with a given block 7, and the result of the comparison in the form of a correction voltage Us (FIG. 2e, t ti.-.tz) from the output of the subtractive amplifier 8 through the switch 10 and the integration unit 5 is fed to another input of the adder 3. As a result of not the output of the adder 3, a control voltage Uy is formed (Fig.26, t ti ... t), the rate of change of which maintains a linear frequency change in the frequency range fH .. .fe (figv, t ti ... tz) PG 2 when neli linear sawtooth voltage Ui GPN 4.

During the reverse stroke of the sawtooth voltage Ui (Fig. 2a, t ti ... t2), the frequency of PG 2 decreases rapidly (Fig. 2c, t

v.2. Dz), as a result of which, at the output of the differentiation unit 6, a negative voltage is generated from (fig. 2d, t ta .-. ts). The threshold element 9 returns to its initial state O and at its output.

the voltage Ue becomes the corresponding logical zero (fig.2j. t ta), which results in closing the key 10. As a result, during the return of PG 2 to the initial state (fig.2b, t t2 ... ta) circuit

Automatic frequency adjustment is disabled and does not affect this process.

Claims (1)

Claims An oscillating frequency generator comprising a series-connected sawtooth generator, an adder, a tunable oscillator, and a frequency detector, as well as a subtracting amplifier characterized in that. that, in order to increase the linearity of the output frequency change, at the beginning of the tuning cycle, a differentiation unit was connected in series, the input of which is connected to the output of the frequency detector, a threshold element, a key and an integration unit whose output is connected to another input of the adder, as well as a setting unit tuning rate, the output of which is connected to the direct input subtractive amplifier, invertorization invert, the output of the subtracting amplifier is connected to the output of the differential unit connected to the key signal input.