SU830645A1 - Pulse repetition frequency-to-dc voltage converter - Google Patents

Description

one

The invention relates to frequency converters to direct voltage and can be used in automatic control systems, telemechanical systems, as well as in measuring and computing devices.

A frequency-to-voltage converter is known based on a digital pulse width modulus, comprising a clock pulse generator connected to the first counter inputs whose outputs are connected to the control trigger inputs whose output is connected to a smoothing filter input, while the second generator output is connected with the first inputs of the synchronization unit, and the second input of the first synchronization unit - with the input thickness 1.

However, this converter is characterized by insufficient accuracy and a small range of change in the steepness of the output characteristic.

The purpose of the invention is to increase the accuracy of the conversion and to expand the range of change in the steepness of the output characteristic.

The goal is achieved due to the fact that in a frequency converter a pulse is transmitted to a DC voltage, which contains a clock generator, connected by a first output to the first inputs of counters, the outputs of which are connected to the trigger inputs, the output of which is connected to the filter input, the pulses are connected to the first inputs of the synchronization blocks, and the second input of the first synchronization block, with an input thickness, has been introduced two switches, each of which is connected between the output of the corresponding about the synchronization unit and the second inputs of the corresponding counter.

In addition, to ensure a smooth adjustment of the slope of the output characteristic within each subband, a controllable delay element is inserted into the converter, the output of which is connected to the second input of the second synchronization unit, and the input to the input bus.

FIG. 1 is a block diagram of the device; in fig. 2 - output characteristics of the converter.

The frequency converter of the pulse following to the voltage of a direct current contains (Fig. 1); 1 clock pulse generator, generating clock pulses FI, Fj, shifted in time by the same intervals, synchronization blocks 2 and 3, providing injection or pulses of the converted frequency f synchronously with clock frequency P., two counters 4 and 5 pulses, trigger 6, a smoothing filter 7, a controllable delay element 8, to the input of which impulses of the frequency being converted, and switches 9-1, 9-2.

The device works as follows.

In the initial state, in the higher discharge of counter 5, a unit is set, which reduces its initial capacity by a factor of two. When the counters are filled with clock pulses Fi, the counter 5 overflows first and changes the state of the control trigger; upon the overflow of the counter 4, the trigger returns to its original state, and this is repeated with each overflow of the counters. In this case, a pulse voltage is formed at the output of the trigger, in which the pulse duration is equal to the pause duration, since the initial capacitance of the counters is twice as large. The average voltage at the output of the filter is zero. When the converted frequency fx pulses arrive, counter 4 is filled with frequency pulses and fx, and counter 5 only with RF frequency pulses since the fx pulses are delayed for some time by element 8. After a period of time t, both counters are filled with frequency pulses fx and F. Consequently , at the initial moment in the counter 4 is recorded for N pulses more than in the counter 5 and due to the integrating properties of the converter the pulse ratio of the pulse voltage at the output of the trigger 6 is changed, which leads to the appearance of the smoothing 7, the filter voltage constant current whose value depends on the value of the converted frequency fx and delay time Lq gelementa 8. UbMx rfxIz Ubbix for expression shows that with a constant "value of m 1 voltage at the output transducer is directly proportional to the frequency converted. When using stabilized power sources and clock generator. Converter error 0.05% or less. Two switches 9-1, 9-2, mechanically interconnected, allow the convertible frequency f to be applied to the inputs of the first, second, and third counters, which makes it possible to select the working frequency range f /. In this case, the slope of the output characteristic of the converter changes stepwise. The coefficient is entered where i is the bit number (starting from the lowest) of the counter, to the input of which the frequency is converted. In this case, UBbix Uo-T- -f. The family of output characteristics of the converter is shown in FIG. 2

A smooth adjustment of the steepness of the input-output characteristic within each subband can be made by changing the time T of the controllable delay element, the circuit of which is built on the elements of digital computer technology and allows the steepness to be adjusted with high discreteness.

Claims (2)

1. A pulse frequency converter to a DC voltage, comprising a clock pulse generator, connected by a first output to the first counter inputs, the outputs of which are connected to trigger inputs, the output of which is connected to the filter input, the second clock generator output is connected to the first 0 inputs of synchronization blocks, and the second input of the first synchronization block — with an input bus, characterized in that, in order to increase the accuracy of the conversion and expansion of the Range of change of the steepness of the output characteristic, two 5 switches, each of which is connected between the output of the corresponding synchronization unit and the second inputs of the corresponding counter. 2. A transducer according to claim 1, characterized in that, in order to ensure a smooth adjustment of the steepness of the output characteristic within each subband, into it. A controllable delay element is introduced, the output of which is connected to the second input of the second synchronization unit, and the input is connected to the input bus. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 199529, cl. G 06 K 1/12, 1968 (prototype). fw f v ../r-t H n -o I () 8 9 70 (put.Z