SU1714785A2 - Former of random signals - Google Patents

Description

The invention relates to radio engineering and communications, can be used in the study of the noise immunity of radio systems and is an improvement of the device according to the author. 1 1649635.5

The aim of the invention is to reduce the level of out-of-band emissions by reducing the quantization step.

FIG. Figure 1 shows a structural electrical circuit of a driver for 10 tea signals; in fig. 2 A, W - diagrams, explaining the principle of operation.

The accident signal generator contains a series-connected reference generator (OG) 1 controlled frequency divider 2 (UDCH), a counter 3, a 4 code converter (PC), a digital converter 1 (D / A converter) 5 and a filter 6, as well as a serially connected frequency splitter (DF), 8 random number generator (RNG), 9 code converter (PC), the outputs of which are connected to the control input of UDN 2. The high-level output of counter 3 is connected to the input of frequency divider 7 and through a capacitor 10, with a bus 25 the reference voltage of the DAC 5.

The shaper of random signals works as follows.

The reference oscillator 1 receives pulses with a for frequency at the input of the UDCH 2, at the output of which the pulse frequency is reduced by Ni times; where NI is the division factor, the code of which is set at the output of PK 9.35

Pulses from the output of UDCH 2 (Fig. 2a) are fed to counter 3 with a capacity of Krch and through DC 7 with a coefficient divided by i KCD - to the clock input of the RNG 8. Through every Katch CDC pulses a signal from the output of RF 7 (Fig. 26) 40 The output of the RNG 8 is set to one of the equal numbers from O to n-1. A certain number at the output of the PC 9 corresponds to the number NI at its output, which determines the pulse frequency 45 at the input of the UDCH 2 for / Ni.

Thus, in total, n predetermined frequencies can be formed, when the code changes at the output of the RNG 8, a new random number I selected from n is determined, which determines the new value of the signal frequency at the UDCH output 2. The frequency of the output signal of the driver is equal to the pulse frequency the output of the highest bit of the counter 3 (Fig. 2d) (Ni-Kech). As a result, 55 kdch oscillation periods of the shaper have the same duration (in Fig.).

Converter 4 of the code is programmed so that with a consecutive increase in the number of its input (address) buses, the numbers at the output of PC 4 change according to a certain (usually sinusoidal) law. Since the most significant bit of the counter does not enter the PC 4, the number at the PC 4 input during one period of the frequency fi changes twice (Fig. 2c), the same happens with the PC 4 output number (Fig. 2e).

Using the DAC 5, the digital signal is converted to analog, while the high discharge pulses of counter 3 (Fig. 2d) are used as the reference voltage, the constant component of which is eliminated using the transition capacitor 10. Therefore, during the first half period the reference voltage is negative and the operation of the CL 5 is in the area of negative output voltages. In the interval of the second half-period, the reference voltage is positive, so the transformation occurs in a positive structural surface. As a result, a full oscillation period is formed at the output of the D / A converter S — negative and positive half waves (Fig. 2e).

Filter 6 smoothes the stepwise nature of the voltage (Fig. 2g).

The resultant, oscillation at the output of the former is a segment containing Kdch periods of sinusoidal oscillations each, the next without a phase break. The oscillation frequency inside the segment is equal to fi and randomly varies from segment to segment, taking one of the previously specified values;

Thus, in the proposed device, the quantization step y | Improved twice due to the introduction of an additional link between the discharge of the meter and the reference voltage bus. Reducing the pitch of quanta leads to a reduction in quantization noise, thereby reducing the level of out-of-band emissions.

Claims (1)

Invention Formula Shaper of random signals according to auth. St. 1b49b35, characterized in that. that, in order to reduce the level of out-of-band emissions by reducing the quantization step, the input of the frequency divider is connected to the inputs of the reference voltage of the analog. converter through the input capacitor. about 11 irn I t I I I flL L I I I t i, f 6 one Sh XY / : FIG. 2