SU1497708A1 - Digital synthesizer of linear-frequency-modulated signals - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to provide the simultaneous formation of two linear frequency modulated signals with different signs of the frequency modulation rate at the same center frequency. The synthesizer contains accumulating adders 1 and 5, clock generator 2, combinational adder 3, trigger 4, converter 6 codes, block of inverters (BI) 7, D / A converters 8 and 9, and bandpass filters 10 and 11. From the pulses of the generator 2, trigger 4 forms a sequence like A "meander" that arrives at BI 7. It performs a direct translation of codes from input to output or inversion of input codes when acting on its control input according to the level of a logical zero or a logical unit. In this case, each second amplitude code is inverted from the output of converter 6, which leads to the inversion of the spectrum read from converter 6 of the original signal. Next, with the BI 7, the amplitude codes go to the DAC 9, which generates a discrete linear-frequency-modulated signal, the spectrum of which is inverse to the spectrum of the original signal, after which the filter 11 converts the discrete signal to a continuous one. The goal is achieved by the introduction of trigger 4 and BI 7. 1 Il.

Description

one

(21) 4227596 / 24-09

(22) 04/13/87

(46) 07/30/89. Бкш № 28 (72) Л, V. Bondar and U. Mo-Romanov (53) 621.376.52 (088.8) (56) Gnatek U. Reference book on digital-analog and analog-digital converters, M .: Radio and communication, 1982, with „255-259.

Kochemasov V.N. et al. Signal generation in linear frequency modulation. M .: Radio and Communication, 1983, pp.55-58,

4i

(54) DIGITAL SYNTHESIZER OF LINEAR-FREQUENCY-MODULATED SIGNALS (57) The invention relates to radio engineering. The purpose of the invention is to provide the simultaneous formation of two linear frequency modulated signals with different signs of the frequency modulation rate at the same center frequency. The synthesizer contains accumulating adders 1 and 5, a clock generator 2, a combination adder 3, a trigger 4, a converter of 6 codes, an inverto block

(L

with

four

WITH

-J

about

00

31497708

poji (VI) 7, NLP 8 and 9 and strip

filters 10 and 11l. From the generator 2 pulses, trigger D generates sequences (1 type of meander, which goes to BI 7. It performs direct translation of codes from input to output or inversion of input codes when acting on its control input, respectively logical l or logical unit. In this case, each BTopoi amplitude code from the output is inverted

The invention relates to radio engineering and can be used in radio receiving and radio transmitting devices.

The purpose of the invention is the simultaneous formation of two linearly frequency-modulated signals with different signs of the frequency modulation rate at the same center frequency.

The drawing shows a structural electrical circuit of a digital synthesizer of linear-frequency-modulated signals.

Digital synthesizer of linear-frequency-modulated signals contains the first accumulating adder (NS) 1, clock generator 2, combination adder (CS) 3, trigger 4 second NS 5, converter 6 codes block 7 inverters, first digital-to-digital converter (IDN) 8, the second / L 9, the first 10 and the second 11 POLAND. FC STREETS

A digital synthesizer of linearly-modulated signals works as follows

The rate of the frequency modulation Kjo is applied to the input of the first NS 1. The capacitance of the first NS 1 determines the frequency deviation of the generated frequency-frequency-modulated signals and is generally less than the speed of the second NS 5 o When the first NS 1 arrives at the synchronization input clock generator 2 it performs summation of the cd code. The code rate of the frequency modulation Cd is determined from the ratio

K - K -.

transducer 6, which leads to the inversion of the spectrum read from the transducer 6 of the original signal. Next, with the BI 7, the amplitude codes arrive at the DAC 9, which forms a discrete linear-frequency-modulated signal, the spectrum of which is inverse to the spectrum of the original signal, after which the filter 11 converts the discrete signal to continuous. The goal is achieved by the introduction of trigger 4 and BI 7. 1 Il.

where f is the value of the clock frequency, / 3 is the velocity value of the generated signals.

N is the capacity Pioporo HC 5. The contents of the first HC 1 for the second cycle are determined by the ratio

К „е, (г) ZK К

BUT

year

The signal from the output of the first NS 1 is supplied to the first group of inputs of the CS 3, the code of the initial frequency K g is formed on its second group of inputs

a linear frequency-modulated signal, which is determined from the

TO

fn

-

where n is the initial frequency.

In KS 3, the codes Kg and the output codes of the first NS 1 are added together. The output code of KS 3 for the rth cycle of operation is determined by

five

50

K ,, (g) Kf

At the outputs of the second HC 5, the phase codes of the synthesized linear-frequency-modulated signals are formed at discrete points in time, the numerical values of which are determined by the ratio

K (r) Z (Kf.Kp) -N-ent li (K.

4vb -.

In this case, the second term on the right side of the discharge is realized automatically by overflowing the second

HC 5, the capacity of which N is equivalent to 2/1.

Thus, the succession of the codes of the instantaneous phase values of the synthesized first linear frequency-modulated signal is formed at the output of the second HC 5. This sequence of codes is used to address the converter to 6 coses, the output of which generates amplitude codes of the 1 si-opiruem signals. In the first DAC 8, the amplitude codes are converted into corresponding analog quantities and a discrete frequency-modulated x signal is generated at its output ( gT), The transition from the discrete to continuous linear-frequent-modular signal is carried out in the first band-pass filter 10. If the capacity of the first HC 1 is N / 4 and the input frequency code is Kg N / 8, then on

I H,

The output of the first band-pass filter 10 generates a sequence of linear-frequency-modulated signals, the instantaneous frequency of which is measured in 3f g dc. -g-

one .

not 1sl from the value of "o

The pulses from the output of the clock generator 2 are fed to the input of the trigger 4, at the output of which a sequence of pulses of the meander type is formed, the period of which is two times longer than the period of the clock pulses. The pulse sequence from the output of the trigger 4 is fed to the control input of the inverter unit 7. When acting on the control input level log. O, the inverter unit 7 performs the forward translation of the codes from input to output. When a control input level 1 is applied, the inverter unit 7 inverts the input codes, and Tё inverts every second amplitude code from the output of the 6 code converter, which results in inversion of the spectrum read from the 6 source code signal x (rT). From the output of inverter unit 7, the amplitude codes arrive at the input of the second DAC 9 and at its output a discrete linear-frequency-modulated signal y (rT) (- 1) (rT) is formed, the spectrum of which is inverse with respect to the spectrum of the signal x (rT )about

Transition from a discrete linear frequency modulated signal to

continuous in the second band-pass filter 11. With the same values of the capacitance of the first HC 1 N / 4 and at the output of the second band-pass filter 11, a sequence of linear-frequency-modulated signals, the instantaneous frequency of which varies from

3fr f t

-g- to g-.

In the general case, the capacity of the first HC1 and the control codes K and Kr- can take times: n1H.1c values. However, to provide the same center frequency of the linear frequency-modulated signals generated, it is necessary that the center frequency of the Jiper frequency in the first signal channel (the output of the first band-pass filter 10) be equal to

f L 0 4

This is subject to

 NJ N 4 4

2K

gn

N,

where N 1 is the capacity of the first NA 1 o

Thus, the introduction of the trigger 4 and the inverter unit 7 allows you to simultaneously generate two linear frequency modulated signals with different signs of the frequency modulation rate and thereby expand the field of application of the digital synthesizer of linear frequency modulated signals, in particular, allows you to create composite frequency linear frequency modulated signals with different laws of frequency modulation, as well as simultaneously form frequency-shifted linear frequency modulated signals.

Claims (1)

Invention Formula A digital synthesizer of linear frequency modulated signals containing series-connected the first accumulating adder, the combinational adder, the second accumulating adder, the code converter, the first digital-to-analogue converter. the caller and the first band-pass filter, a second digital-to-analog converter and a second band-pass filter connected in series, the synchronization input of the first accumulating adder being combined with the input 7 U977088 synchronization of the second accumulator between the output of the clock generator of the adder and connected to the output of the clock and serial inputs of the second digital generator, which distinguishes the analog converter by introducing the fact that, for the purpose of simultaneous connected in series the trigger of forming two linear frequency and inverter unit, the same The inputs of the modulated signals with different signals are connected to the corresponding signs of the speed of the frequency modulating bit-wise outputs, with the same central often those tel codes.