Accasional converter

 

(57) Abstract:

The invention relates to computer technology and can be used in information-measuring systems. The purpose of the invention is improving the accuracy with ease of implementation and high performance. The Converter contains a voltage reference, an amplifier with adjustable gain 1 and unit 2 extract the square root of the difference between known and unknown quantities, and the dependence of the implemented Converter has the form, where X is the argument, X = UI/Uo(max); 0,7071 < x < 1.0, the B - factor . 1 C.p. f-crystals. 2 Il.

The invention relates to computer technology and can be used in information-measuring systems, as well as in various functional converters, when you want to determine the value of arccos X is a high performance, low accuracy and ease of implementation in some interval of values of the argument from 0,7071 to 1.0, this should provide a large dynamic range for input signals.

Known arccosine converters time-pulse type [1] which, although having low error transformation is possible inverse trigonometric transformations [2] contains the Comparators, the reference oscillations, a counter the number of pulses at the output of which is proportional to the changing corner.

The device is quite complicated to implement, has low performance.

Know another device [3] accasional d / a Converter, which although it has a small truncation error is not more than 0.1 requires the use of complex digital devices, which in combination with the analog signals irrational.

The closest General technical characteristics is accasional Converter [4] contains the amplifier, whose input is connected to the reference voltage, the output is connected to the inverter output, and a negative correlation circuit of the amplifier reference voltage and the nonlinear elements in the form of diodes.

The device is quite simple in execution, has high speed, large dynamic range of input signals, a small number of cells with a small number of breakpoints, but this kind of approximation gives a large error of approximation for interval change in the argument from 0,7071 to 1.0, which corresponds to the measurement of angles from 4 to zero.

In such a Converter can p is very difficult to perform and have quite a lot of instrumental error, because errors of several nonlinear links will determine the overall error.

The purpose of the invention to improve the accuracy of measurement with ease of implementation and high performance.

The essence of the invention lies in the fact that with limited argument value, for example 0,7071 X 1.0 approximation you can make a simple function with high precision, specifying the following approximate equation:

arccos X = (/4)f(x) for 0,7071X1,0, (1)

where X is the value of the argument:

< / BR>
And the coefficient chosen from the condition of minimization of the approximation error.

Goal arccosine the Converter comprising an amplifier with an adjustable gain, the input of which is connected to the reference voltage, the output is connected to the output of the Converter is achieved in that the Converter further comprises a unit for extracting the square root of the difference between known and unknown quantities, the first input of which is connected to the reference voltage and the second input is connected to the input transducer, the output of the latter is connected to the output of the amplifier with adjustable gain control input of which is connected to the output baudrate of the difference between known and unknown quantities contains the block to calculate the square root and the subtraction unit; the first and second inputs of the latter is connected to the first and second inputs of the block to extract the square root of the difference between known and unknown quantities, respectively, the output of the subtraction unit is connected to the input unit for extracting the square root, the output of which is connected to the output unit for extracting the square root of the difference between the known and the unknown quantity.

In Fig.1 shows a structural diagram arccosine Converter. It includes:

the amplifier 1 with an adjustable gain;

unit 2 to extract the square root of the difference between known and unknown quantities.

Blocks in arccosine the Converter is connected as follows. The voltage reference is connected to the first inputs of the amplifier 1 with an adjustable ratio transmission unit 2 to extract the square root of the difference between known and unknown quantities. The input of the Converter is connected with the second input unit 2 to extract the square root of the difference between known and unknown quantities, the yield of the latter is connected to the control input of the amplifier 1 with an adjustable gear ratio. The output of the controlled amplifier 1 is connected to the output arccosine Atego of the difference between known and unknown quantities. It includes a subtraction unit 3 and unit 4 for extracting the square root. The first and second inputs of the block 2 to extract the square root of the difference between known and unknown quantities are connected with the first and second inputs of the subtraction unit 3, respectively. The output of the latter is connected to the input unit 4 for extracting the square root, the output of which is connected to the output unit 2 to extract the square root of the known and unknown quantities.

Accasional the Converter operates as follows. The voltage from the reference voltage Uopsupplied to the first inputs of the amplifier 1 with an adjustable ratio transmission unit 2 to extract the square root of the difference between known and unknown quantities. Input voltage Uxcorresponding to the value of the argument X, is fed to the second input unit 2 to extract the square root of the difference between known and unknown quantities. The output of block 2 to extract the square root of the difference between known and unknown quantities get the voltage U2that depends on the voltage Ux. This voltage U2controls the gain of the controlled amplifier 1. The voltage U3the output unit>to the input of the unit 4 for extracting the square root, the output of which receives the voltage U4equal values of Uopand And choose such magnitude that when the control voltage is equal to the gain controlled amplifier 1 will be equal to 1 unit. The voltage U2the output of block 2 to extract the square root of the difference between known and unknown quantities can be represented in the following form:

(2)

where the factor a is chosen in accordance with (1).

This voltage U2is supplied to the control input of the amplifier 1 with an adjustable gear ratio. The transmission coefficient of this controlled amplifier 1 is directly proportional to the control voltage U2that varies in accordance with the expression (2), so the output voltage U1can be written as follows:

(3)

Consequently, the received expression in accordance with (1).

< / BR>
And the coefficient chosen from the condition of minimization of the approximation error.

The approximation error of q can be obtained from the following expression:

For example, when a 3,4142 error q depending on 0,7071 X 1.0 will correspond to the error in opredelitsea size 0,22oget the value of the truncation error, which will correspond to q/2, i.e 0,22o.

The ease of implementation provides a small amount of instrumental error, which will not exceed the truncation error if the error of the gain controlled amplifier 1 is not more than 0.4 for values of Uxclose to values of 0.7 Uopand for values of Uxapproaching the value of the voltage Uoperror transfer coefficient can reach tens of percent, without affecting the accuracy of the device. Similar requirements apply to the unit 2, to extract the square root of the difference between known and unknown quantities. This is because the value of the measured angle is reduced to zero when equal voltages Uxand Uop. Such accuracy requirements used blocks is easy to perform.

The Converter is implemented using conventional units, known in the literature:

controlled amplifier 1 control ratio of the transmission is effected by changing the resistance of the feedback resistor, or using a controlled voltage divider [5,a]

block 2 for isolateswere square root (6) or by means of a logarithmic amplifier for OC - (5,b).

The sources of information

1. Edited Smolova and etudes "Time-impulse computing systems", Chapman and hall, 1983, page 266.

2. Auth. mon. USSR N 1508248, G 06 G, 7/22, 1989.

3. Auth. mon. USSR N 1410063, G 06 G, 7/23, 1988.

4. Edited by j.Graham. The use and design of operational amplifiers, M. Mir, 1974. page 279.

5. Alexenko A., Colombel E. A. Starodub, I. Application of precisionid analog IP. M. Owls.radio, 1980, a) S. 63; b) S. 77.

6. Auth. mon. USSR N 721831, G 06 G, 7/20, 1980.

1. Accasional Converter comprising a voltage reference and amplifier with adjustable gain, information whose input is connected to the output of the reference voltage, and the output is the output of the Converter, characterized in that it introduced the block extracting the square root of the difference between known and unknown quantities, the first and the second input of which is connected to the output of the reference voltage and to the input of the Converter, and the output connected with the control input of the amplifier with adjustable gain.

2. The Converter according to p. 1, characterized in that arccosine dependence has the form

<

 

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