SU1225039A1 - Digital frequency-shift keyer - Google Patents

Abstract

The invention relates to radio engineering and m. used in radio, radio telegraphy and wired data transmission systems. The level of out-of-band components of the signal spectrum is reduced. The device contains a reference generator 1, counters (C) 2 and 3, elements OR 4 and 13, frequency divider 5, D / A converter 6, D-flip-flop 7, band-pass filter (PF) 8 and elements 9-12. The sequence of square impulses with the frequency f is fed from the output of the reference generator 1 to the input C 3. The conversion factor C 2 and 3 is switched according to the incoming information sequence. C 3, frequency divider 5 and C 2, connected in series, divide the frequency up to the value of the clock frequency F, which allows to obtain a phase-controlled frequency-manipulated signal, which is filtered in the IF 8 and supplied to the output of the manipulator. The goal is achieved by the introduction of C 2 and 3, the elements OR 4 and 13, the DAC 6, the D-flip-flop 7, and the elements 10 - 12. t Il. g eo s IND yu sp; O

Description

The invention relates to radio engineering and can be used in radio communications, telegraphy and wired data transmission systems.

The purpose of the invention is to reduce the level of the out-of-band components of the signal spectrum.

The drawing shows a structural electrical circuit of the proposed manipulator.

Digital frequency manipulator contains reference generator 1, first and second counters 2 and 3, first element OR 4, frequency divider 5, digital-analog converter 6, D-flip-flop 7, band-pass filter 8, first, second, third and fourth elements 9 - 12, the second element OR 13

The manipulator works as follows.

The reference generator 1 generates a sequence of rectangular pulses with a frequency f. Which is fed to the input of the second counter 3. The switching of the conversion factors of the first and second counters 2 and 3 is performed according to the incoming information sequence. The proposed manipulator allows one to obtain a phase-free but manipulated signal, which can be shown by the example of the MNC signal with the manipulation index of m 0.5.

Denote the frequencies to be manipulated as f, and f (f, fj) then the separation between frequencies is equal to lР f - f2

If the manipulation index is m 0.5, then the clock frequency is F AF. The frequency of the reference generator 1 can be written as for N, n f, 5 where N, and N, are the conversion factors of the first and second counters 2, 3; n is the division factor of the frequency divider 5. The difference in the N coefficients, and N, is chosen minimal, which can be written as N 2 - N 1. The division factor of the frequency divider 5 is n 2, where K is the digital-analog converter 6.

Thus, serially connected second counter 3, frequency divider 5 and first counter 2 produce frequency division f (, r to F, which allows to obtain a phase-free frequency-manipulated signal.

CHPHaj i from the first and second counters 2 and 3 are respectively transmitted to the third, fourth and first, second elements AND 11, 12, 9 and 10, from whose outputs the signals are collected respectively on the second and first elements OR 13 and 4.

The above listed elements form two dividers with a variable delay ratio (DFD), the outputs of which produce frequency-modulated signals with a continuous phase (MNF) with an average frequency of Nf. The signals from the outputs of the first and second elements, OR 4 and 13, are respectively fed to frequency divider 5 and to; The C input of the D flip-flop 7. The manipulation signal is applied to the D-input of the B-trigger 7.

The phase-free frequency-manipulated signal is filtered in the band-pass filter 8 and is fed to the output of the manipulator.

Claims (1)

Invention Formula Digital frequency manipulator, containing a reference oscillator, a frequency divider, a band-pass filter, and an AND element, characterized in that, in order to reduce the out-of-bandwidth components of the signal spectrum, a second one is entered into it, the third and fourth And elements, two OR elements, a digital-to-analog converter, two counters and a D-flip-flop, the outputs of which are connected to the second inputs of the first and second And elements, the outputs of which are connected to the inputs of the first OR element, and to the second inputs of the third and fourth elements And, the elevations of which are connected to the inputs of the second OR element, the output of which is connected to the C input of a D-flip-flop, the D input of which is the information input of the manipulator, and to the first input of the first counter, the second input and output of which are connected With the single output of the frequency divider, the other outputs of which are connected to the inputs of the digital-to-analog converter, and with the first inputs of the third and fourth elements I, the output of the reference generator is connected to the first input of the second counter, the second input of which is connected to the code of the first elec 312250394 OR and the input of the frequency divider, elements AND, the output of the digital-analog output and the outputs of the second counter are connected to the converter connected to the input to the first inputs of the first and second band-pass filter.