SU1674097A1 - D-a generator with variable signal spectrum - Google Patents

Abstract

The invention relates to the field of automation and radio metering technology and can be used, in particular, for checking analog-digital spectrum analyzers and searching for the resonant frequencies of objects under study. The purpose of the invention is to expand the field of application by reproducing complex signals with a uniform spectrum of harmonic components. The digital-to-analog generator with a tunable signal spectrum contains two registers 2 and 7, two counters 3 and 10, a code comparison circuit 4, accumulating adder 5, block 8 of the ordinate memory and digital-analog converter 9. In the generator, the transition to reproduction of each new harmonic component is performed the overflow signal of the second counter, which makes it possible to equalize the time of their reproduction and to ensure uniform spectral response. 2 Il.

Description

one

(21) 4718134/24 (22) 07/11/89 (46) 08/30/91. Bul №32

(71) All-Union Research and Design Institute for Gas Processing

(72) V.M. Mail (53) 681.325 (088.8)

(56) Gnatek Yu.R. Handbook of digital-analog and analog-to-digital converters. M .: Radio and Communications, 1982, p. 255.

USSR author's certificate in application Ns 4435496/24, cl. G 06 F 1/02, 1988

(54) DIGITAL-ANALOG GENERATOR WITH REVERSIBLE SIGNAL SPECTRUM

(57) The invention relates to automation and radio measuring technology and may be

used, in particular, to test analog-digital spectrum analyzers and search for the resonant frequencies of the objects under study. The purpose of the invention is to expand the field of application by reproducing complex signals with a uniform spectrum of harmonic components. The digital-to-analog generator with a tunable signal spectrum contains two registers 2 and 7, two counters 3 and 10, a code comparison circuit 4, accumulating adder 5, block 8 of the ordinate memory and digital analog converter 9. In the generator, the transition to reproduction of each new harmonic component performed on the overflow signal of the second counter, which makes it possible to equalize the time of their reproduction and to ensure uniform spectral response. 2 Il.

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ABOUT

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The invention relates to automation and a radio measuring technique and can be used to test analog-digital spectrum analyzers, as well as to search for the resonant frequencies of an object subject to a wide spectrum of signals.

The purpose of the invention is to expand the field of application by reproducing complex signals with a uniform spectrum of harmonic components.

FIG. 1 shows a block diagram of a digital-analog generator with a tunable signal spectrum; in fig. 2 is an example of a spectral characteristic of a reproducible signal.

The generator contains the input 1 of the initial frequency setting, the first register 2, the first counter 3, the code comparison circuit 4, accumulating adder 5, the input of the final frequency reference 6, the second register 7, the ordinate memory block 8, digital-to-analog converter (DAC) 9, the second counter 10 and the bus 11 input clock frequency.

The digital-to-analog generator with a tunable signal spectrum works as follows.

Initial state: the initial frequency value is entered into input 2 via input 1 of the initial frequency, the final frequency value is entered into input 7 via input 6 of the final frequency, the values of the sinusoid ordinates are stored in block 8, and the contents of the first counter 3 have the contents of register 2 The second counter 10 is in the zero state.

According to the operation algorithm of accumulating adder 5, its output code at any time contributes to the address of a certain sinusoid ordinate, the ordinate code, which is sewn into block 8, enters through the DAC 9 to the generator output.

If the contents of register 2 are not equal to the contents of register 7, then after the generator generates one initial frequency period (which coincides with the overflow of the second counter 10), the pulse from the overflow output of counter 3 increases by one, after which the formation begins the sinusoida of the next frequency value, the code of which is increased by one. At the end of the cycle of forming the next harmonic component of a complex signal, the next overflow pulse of the second counter 10 increases the code of the frequency value by one. Further, the process is repeated until the comparison circuit 4 with the equality of the current and final values

Frequencies will not give a comparison impulse. A pulse at the recording resolution input of the counter 3 at the output of the latter appears again the value of the initial frequency code, and the process of forming a complex signal is repeated.

Counter 10 forms a time interval during which only one harmonic component of the complex digital oscillator signal is played.

Since each subsequent harmonic component of a complex signal is reproduced during the time interval between two adjacent overflow pulses of counter 10, the temporal development of the complex signal reproduced by the generator occurs similarly to the preceding intervals.

The spectrum distribution of the amplitudes of the real signal corresponds to the envelope shown in FIG. 2. Pulsation of the envelope due to the fact that after each pulse of the overflow there is a change in the speed of reproduction of the signal.

A digital signal analyzer, by measuring the amplitude spectrum of such a signal, as a result yields the line distribution shown in FIG. 2 ordinates with harmonic component amplitudes.

Claims (1)

Invention Formula A digital-to-analog oscillator with a tunable signal spectrum containing an ordinate memory block connected by an output to an input of a digital-to-analog converter connected to an output of a generator; and the output to the information input of the accumulating adder and the first input of the comparison circuit, the second input of which is connected to the output of the second register, and the information input The first and second registers are connected to the input inputs of the initial and final frequencies of the generator, respectively, characterized in that in order to expand the field of application by reproducing complex signals with a uniform spectrum of harmonic components. the counting input of the first counter is connected to the overflow output of the second counter, connected by the counting input to the generator clock input bus and the clock input of the accumulating adder connected by the output to the address input of the ordinate memory block.