SU792528A1 - Frequency-modulated signal shaping device - Google Patents

Description

one

The invention relates to communication technology and can be used in radar and measurement technology.

A device for generating frequency-modulated signals, containing a series-connected reference oscillator and a synchronizer, a controlled oscillator, whose inputs are connected to the outputs of the modulator and correction unit, a comparison unit and sum-O is known.

mat 1

However, the known device has a low accuracy setting the Law of Frequency Modulation.

The aim of the invention is to improve the accuracy of setting the law of frequency modulation while reducing noise in the output frequency-modulated signal.

To do this, in the device for generating frequency-modulated signals, containing a serially connected reference oscillator and a synchronizer, a controlled oscillator, whose inputs are connected to the outputs of the modulator and correction unit, a comparison unit 25 and an adder, between the first synchronizer output and one sequentially connected pulse generator, address counter, memory block and 30 are entered from the adder inputs

a digital-to-analog converter, between the output of the controlled generator and the first input of the comparison unit, a frequency divider with a power control device is entered, and the output of the pulse generator is also connected to the second input of the comparison unit via an input key, the other input of which is connected to the output of the reference generator; to another input of the adder, the output of which is connected to the input of the correction unit, the second output of the synchronizer is connected to the input of the modulator, and the third output - to the control at the entrance of the address counter.

In the drawing is a structural electrical circuit diagram of the proposed device for generating frequency-modulated signals.

The device for generating frequency-modulated signals contains a reference oscillator 1, a synchronizer 2, a controlled oscillator 3, a modulator 4, a correction block 5, a comparison block 6, an adder 7, a pulse generator 8, an address counter 9, a memory block 10, a digital-analog converter 11, a divider 12 frequency with power control device and key 13.

The device for the frequency-modulated signals operates as follows.

When the frequency changes along the linear in the device, as a result of the pulse-phase auto-tuning, the initial frequency f, is established. Pulse generator 8 In this mode, it generates pulses with a constant period that is a multiple of the clock frequency f of the signal coming from synchronizer 2 output. 8 pulses per pulse formation mode, the instants of occurrence of which are CJ, with an accuracy of up to /. coincide with moments of time i / determined from equality

.-e Wtf / T Yr

where V is the frequency deviation;

T is the duration of the signal;

K. is the frequency division factor;

1 -, 2,3 ... - the number of periods

the frequency-modulated signal at the output of the splitter 12 frequency, passed from the beginning of the modulation.

When comparing the pulse sequences arriving at the input of the comparison block b from the frequency divider 12 and the key 13, errors are obtained by gating the frequency-modulated oscillation with radio pulses. Error measurement is carried out with a systematic error due to the difference of -t from t and is calculated by the formula 1

dc (2 Wtf D.) K - 21C.

The values of these errors in digital form, as well as the values of lpdf stored in block 10 of memory, reading from which is carried out sequentially in accordance with the address g currently formed in the address counter 9. The latter in the modulation mode performs the score impulses from the generator output 8 pulses In the auto-tuning mode in all bits of the address counter 9

zeros are set. The information read from memory block 10 is converted to analog form in digital-to-analog converter 11 and compensates for systematic error of block 6 in adder 7. The error signal obtained as a result of this compensation, after passing through correction block 5, adjusts the frequency of controlled generator 3 in accordance with the specified law of variation frequencies.

In the proposed device for generating frequency-modulated signals, high accuracy is ensured.

maintaining a predetermined frequency law of such modulation and low noise in the output frequency-modulated signal.

Claims (1)

1. US Patent No. 3382460, cl. 331-178, published. 1968 (prototype).