SU1713080A1 - Digital generator of frequency-modulated signals - Google Patents

Abstract

The invention relates to radio engineering and communications and can be used in measurement technology. The aim of the invention is to expand the frequency range while increasing the linearity of the modulation characteristic. The generator with digital frequency modulation contains a reference oscillator 1, a controlled frequency divider 2, an adder 3, a filter 4, and a converter 5 of codes. The adder 3 provides a process for balancing the signal at the high-order output of the controlled divider 2 for any given division factors. 2 Il.

Description

SP

with

with about

00

about

The invention relates to radio engineering and communications and can be used in measurement technology.

The purpose of the invention is to expand the frequency range while increasing the linearity of the modulation characteristic.

FIG. Figure 1 shows the electrical circuit diagram of a digital generator of frequency-modulated signals; in fig. 2 - time diagrams that show his work.,

The digital generator comprises a reference generator 1, a controlled frequency divider 2, an adder 3, a filter 4 and a block 5 of permanent storage.

The digital generator of frequency-modulated signals operates as follows.

The pulses from the output of the reference oscillator 1 (Fig. 2a) are fed to the counting input of the controlled divider 2, on the discharge outputs of which i linearly decreases from N to zero {Fig. 26). The code of the number i is fed from the bit outputs of the controlled divider 2 to the first group of inputs of the adder 3. The value of the number N to the first, second, ..., kth information inputs of the controlled divider 2 is fed from the first, second k-ro

the outputs of block 5. The second group of inputs of the adder 3 receives the code number N / 2. Adder 3 sums the number N / 2 with the current value of 1. When the number i exceeds N / 2, the output of the transfer of adder 3 (in the interval N / 2 i N) maintains the level of logical 1 (Fig. 2b). Therefore, the duty cycle. Output signal of the adder 3 is equal to two.

Using filter 4, the first harmonic of the signal is extracted, with the result that a sinusoidal oscillation is generated at the output of the digital generator of frequency-modulated signals, the frequency of which is determined by the ratio

.

Block 5 amends the control codes so that the frequency dependence of the output signal on the input number is linear. However, if necessary, any dependence of the output signal frequency on the value of the control code can be set.

Formula of the Invention A digital generator of frequency-modulated signals comprising a series-connected reference oscillator and a controlled frequency divider, a permanent memory unit and a filter, characterized in that, in order to expand the frequency range while simultaneously increasing the linearity of the modulation characteristic, an adder is introduced, The first, second, ..., k-th inputs of the signal of the first group of inputs of which are connected respectively to the first, second, k-th bit outputs of the controlled frequency divider, while the first, second k-th information inputs of the controlled frequency divider coupled to the first vtorymk th

the outputs of the permanent storage unit, the second, third k-th outputs of which are also connected to the first, second, ..., (kl) -M inputs of the signal of the second group of inputs of the adder, the filter input is connected to the output, transfer of the adder, k-th signal input the second group of inputs of which is a logic O input, the address input of the Permanent Memory Unit is the frequency control input of a digital generator of frequency modulated signals.

 f,

Have

: / V7

/

FIG. 2

Claims (1)

Claim A digital frequency-modulated signal generator comprising a reference oscillator and a controllable frequency divider connected in series, a constant memory unit and a filter, characterized in that, in order to expand the frequency range while increasing the linearity of the modulation characteristic, an adder is introduced, the first, second, ... .k-th signal inputs of the first group of inputs of which are connected respectively with the first, second ..... k-th bit outputs of the controlled frequency divider, while the first, second ..... k-th information the inputs of the controlled frequency divider are connected to the first, second ..... k-th outputs of the permanent memory unit, the second, third ..... k-th outputs of which are also connected to the first, second, ..., (k-1 ) -th signal inputs of the second group of inputs of the adder, the input of the filter is connected to the output, transferring the adder, the k-th signal input of the second group of inputs is an input of logical 0, the address input of the permanent storage unit is the frequency control input of a digital generator of frequency-modulated signals.