SU1659819A1 - Humidity digital transducer - Google Patents

Abstract

The invention relates to analytical instrumentation, in particular, to primary moisture converters with preliminary signal processing, and can be used in microprocessor based systems for measuring environmental parameters. The aim of the invention is to improve the accuracy of the digital humidity converter. This is achieved by introducing into the device a comparison channel with a model primary moisture transducer and two keys associated with two blocks of data selection and storage. In the pre-cycle, a code is set corresponding to the reference moisture value. In a measurement cycle, by means of a counterbalancing, the voltages from the working primary converter and the reference one are compared with the subsequent conversion to a digital code that carries information about the relative humidity. 1 il. cl

Description

The invention relates to analytical instrumentation, in particular, to primary moisture converters with preliminary signal processing, and can be used in microprocessor based systems for measuring environmental parameters.

The aim of the invention is to improve the accuracy of a digital humidity converter (DSP).

The drawing shows a block diagram of the CPV.

CPV contains a primary humidity converter (PP) 1, the first two-position key 2, the first block 3 of the sample-x information, the digital-analog converter 4 (DAC), the comparator 5, the DAC 4 and the comparator 5 are included

conversion unit 6, functional converter (AF) 7, second storage information sampling unit 8, second two-position switch 9, reference source 10, humidity reference model 11 (initial) converter, added resistance 12. The first input of comparator 5 is at the same time, the first input of block 6. The output of comparator 5 is the output of the CHC. The second input of the comparator is connected to the output of the DAC 4. The simultaneous output of the block 6. Which is connected to the PC through the sample-storage block 3, which is connected to the normally open contact of the first key 2. The movable contact of which is connected to the first input bis I

sl o

00

Yu

the house of the sampling-storage unit 8, the output of which is connected to the normally open contact of the second key 9. The movable contact of the key 9 is connected to the second input of the block b, which is simultaneously the input of the DAC 4. The output resistance of the source 10 is connected in series by the additional resistance 12 and the OPP 11. The common point of their connection is connected to the normally closed contact of key 2. The output of source 10 is connected to the normally closed contact of key 9.

The device works as follows.

Humidity is converted to PP1 into an analog signal. Block 6 converts the measured analog signal to digital by a bit-balancing method. The circuit solution allows, in a measurement cycle, to power the DAC 4 along the reference voltage circuit with the output signal OPP 11 of humidity, and powering the PP1 humidity to produce the output voltage of the DAC 4. In this case, in the cycle preceding the measurement, it is established:

Vi Von-Kdo-V2 Von-KuAn-N0;

where Vi is the voltage at the output of the DAC 4;

/ 2 is the voltage at the output of the FP 7;

Von is the source voltage 10;

Кцдп, Кдо - scale coefficients of the DAC 4 and the analog path OPP 11;

No - the course set in the preliminary cycle;

(ro - model value of humidity.

These voltages are stored in the fetch storage units 3 and 8, respectively. In the measurement cycle, switches 2 and 9 are switched. At the same time, PP1 powered from the first sample-storage block 3 is turned on in the measuring path, and the output of the second sampling-storage block 8 powers the input of the DAC reference voltage 4. The digital code is set at the digital inputs of the DAC 4 N, corresponding to the measured humidity (p. At the same time, the voltage equilibrium is established at the inputs of the comparator 5

Von "UAnNoK do Von Kdo po Ktsdp N.

Taking into account the identity of the primary converters:

N

R TZ-CR

(3)

Invention Formula

10 A digital humidity converter containing a primary converter, a functional converter, a reference voltage source and a conversion unit with a digital-to-analog converter, characterized in that, in order to improve the accuracy of the conversion, an exemplary primary converter, an additional resistance, two two-position keys and two blocks are introduced into it sample data storage, and a comparator is entered into the conversion unit, the first input of which is the first input of the conversion unit and the output is output th digital converter humidity

25, the second comparator input is connected to the output of a digital-to-analog converter, which is simultaneously the output of a conversion unit, which through the first sample-storage unit is connected to a primary converter, which is connected to a normally open contact of the first key, the movable contact of which is connected to the first input of the block through a functional converter the transducer and with the input of the second sampling-storage unit, the output of which is connected to the normally open contact of the second key, the movable contact to connected to the second input of the conversion unit,

40 which is simultaneously a digital-to-analog converter, a series-connected resistor and an exemplary primary driver are connected to the output of the voltage source, and the common connection point is connected to the normally closed contact of the first key, the voltage source output is connected to the normally closed contact of the second key .

Claims (1)

Claim A digital humidity transducer comprising a primary transducer, a functional transducer, a reference voltage source, and a digital-to-analog transducer, characterized in that, in order to improve the conversion accuracy, an exemplary primary transducer, additional resistance, two on-off switches, and two sample-storage units are introduced into it information, and a comparator is introduced into the conversion unit, the first input of which is the first input of the conversion unit, and the output is the digital output moisture converter, the second input of the comparator is connected to the output of the digital-to-analog converter, which is also the output of the conversion unit, which is connected through the first sampling-storage unit to the primary converter, which is connected to the normally open contact of the first key, the movable contact of which through the functional converter is connected to the first input conversion unit and with the input of the second storage fetch unit, the output of which is connected to the normally open contact of the second yucha, the movable contact of which is connected to the second input of the conversion unit, which is also the input of the digital-to-analog converter, the series-connected additional resistance and the model primary converter are connected to the output of the reference voltage, and the common point of their connection is connected to the normally closed contact of the first key, the output of the reference voltage source connected to the normally closed contact of the second key.