SU1277363A2 - Generator of linear-frequency-modulated signals - Google Patents

Abstract

The invention relates to radio engineering and is an improvement of the invention according to the author. No. 862354. The purpose of the invention is to increase the linearity of modulation x-ki. The linear-frequency-modulated signal generator contains a sawtooth voltage generator I, adder 2, ADC 3, differentiating circuit 4, reactive element 5, low-pass filters (LPF) 6, 16 operational memory unit 7, pulse shaper 8, high-frequency generator ( GHF) 9, differential amplifiers 10, 11, memory register 12, elements And 13, 19, single-band modulator 14, .ЛЗ 15, A / D converter 17, D / A converter 18, mixer 20, phase detector 21, reference generator 22, switch 23, source 24 support stress. When disabled LZ 15 when tuning the frequency of the GHF 9, the phase detector 21 generates a signal, respectively. the non-linearity of the phase-frequency x-ki of the mixer 20. This signal through the ADC 17 is recorded in the block 7 of the operational memory. In the subsequent, the LS 15 is connected and the switch 23 is set to the position (at which O is set at the input of the element 13). In this case, the differential amplifier I1 selects the signal for deviations from linearity. This signal corrects the signal for the GHF 9. 1 or . 00 about with NJ

Description

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The invention relates to radio engineering, can be used to generate linear-frequency-modulated signals in radio communications, as well as in panoramic radio-measuring devices, and is an improvement of the known device according to the main auth. No. 862354-.

The purpose of the invention is to improve the linearity of the modulation characteristic.

The drawing shows a structural electrical circuit of the proposed generator of linear-frequency-modulated signals.

The linear frequency modulated signal generator comprises a sawtooth voltage generator 1, an adder 2, a first analog-to-digital pre-converter (ADC) 3, a differentiating circuit 4, a reactive element 5, an additional low-pass filter 6 (LPF), a rapid-memory unit 7, shaper 8 pulses, high frequency generator 9, differential amplifier 10, additional differential amplifier Ml, memory register 12, first element I 13, single-side modulator 14, delay line 15, low pass filter 16, second ADC 17, digital-analogue the expander (D / A converter) 18, the second element I 19, the mixer 20, the phase detector 21, the reference generator 22, the switch 23, the source 24 of the reference voltage.

The generator of linear-frequency-modulated signals works as follows. I

Preliminarily, delay line 15 is disconnected from the generator units of the linear-frequency-modulated signals, and switch 23 is set in such a position that a high potential is established at the input of the first element 13. In this case, when tuning the frequency of the high-frequency generator 9 at the output of the phase detector 21., a signal corresponding to the non-linearity of the phase-frequency characteristic of the mixer 20 takes place.

At the beginning of the frequency tuning by differentiating the sawtooth voltage of the generator 1 in the differentiating circuit 4, a pulse is formed that synchronizes the pulse shaper 8. At its output takes place

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a sequence of pulses whose frequency is significantly higher than the frequency of the generator 1, but a multiple of it. Each pulse of the imaging unit 8 and 5 pulses is synchronized to the first ADC 3, the output digital code of which is proportional to the output voltage of the generator 1, and consequently, to the frequency of the high frequency generator 9.

О This code goes to the bit address inputs of block 7. A code signal from the second A / D converter 17, which is synchronized by the same pulse as the first A / D converter 3, enters its bit signal inputs. Since it is at the same input of the first element I 13. A high potential is established, the signal to the block memory is sent to the input of block 7.

20 7 a digital signal is recorded from the second ADC 17. Thus, each memory of block 1 stores the value of the phase-frequency characteristic of the mixer 20, and the number of this cell

set by code from the first ADC

3, which corresponds to the unique frequency. Consequently, in block 7, the phase-frequency characteristic is recorded with a discrete frequency determined by the ratio of the frequency of the driver. 8 pulses and generator 1.

Subsequently, delay line 15 is connected to linear frequency modulated oscillator blocks.

signals, and the switch 23 is set to such a position that the zero potential is set at the input of the first element And 13, and at the input of the second element

And 19 is high potential. Then at the output of the low-pass filter 16 there is a voltage proportional to coC, + Sq, where (jO is the frequency of the high-frequency generator 9 and Btp is the phase-frequency characteristic of the mixer 20.

Since a high sweep is installed at the input of the second element I 19, pulses from the driver 8 pulses are input to the recording input of block 7, while the contents of the memory of block 7 are written to register 12 of memory. Consequently, transformed; -, a voltage in the analog form in the D / A converter 18 and a filtered low-pass filter 6 voltage at the input of the differential amplitude: a 11 is 5p.

Claims (1)

At the output of the differential amplifier 11, the voltage is Ot-j + S (p + 8 c) - Vf. The deviation from the linearity of the specified voltage is extracted in the differential amplifier 10 by comparison with the linear voltage supplied to its other input from the generator 1. The extracted nonlinearity signal is summed in the adder 2 with the tuning signal from the generator 1 and corrects the signal of the generator 9 high frequencies Thus, in the correction signal, the component corresponding to the nonlinearity of the phase-frequency characteristic of the mixer 20, which limited the linearity of the frequency tuning, is eliminated. The invention is a generator of linear-frequency-modulated signals auth.St. No. 862354, characterized in that, in order to increase the linearity of the modulation characteristic, serially connected reference voltage source and switch are introduced into it, the output of the low-pass filter is connected to the first input of the differential amplifier through the input of an additional differential amplifier, between the saw generator output Three terminals and a second input of an additional differential amplifier are introduced in series, the first analog-to-digital converter, the operational control unit minani, a memory register, a digital-to-analog converter and an additional low-pass filter, between the output of the phase detector and the signal inputs of the operational block. A second analog-to-digital converter is inserted between the output of the saw-tooth generator and the synchronization input of the first analog-to-digital converter. serially connected differentiating circuit and pulse shaper are inserted, the first element I is inserted between the output of the imiuli generator and the write input of the operational memory block, between the output of the pulse former and the read signal input of the operational memory unit, the second element and the second input are entered. the input of the second element And are connected respectively to the first and second outputs of the switch, and the synchronization input of the second analog-to-digital converter is connected to Exit pulse shaper.