SU699358A1 - Noise thermometer - Google Patents

Description

(54) SHDOW THERMOMETER

laziness, delay unit 7, comparison circuit 8, logic device 9, adjustable power supply 10, and computing device 11.

Noise thermometer works as follows

In the absence of ps laugh and temperature change, switch 2 connects the noise measurement channel to resistor 1. In this case, in the noise measurement pool, the signal is accumulated at the integrator. Scheme 4 is closed. In parallel, a measurement is made of the resistance of the noise resistor 1, which is proportional to the temperature. The bandwidth of the resistance measurement channel is equal to the bandwidth of the noise channel. This is necessary to ensure that both channels are equally sensitive to interference. The switch is designed to reduce the supply time of the noise resistor in the resistance measurement mode. This is necessary to reduce the temperature tolerance of the measurement, caused by heating the noise resistor with the supply current. The delay unit 7 delays the signal proportional to the resistance of the noise resistor 1 by one measurement clock, as a result, the comparison circuit 8 compares the previous and current resistance values in each measurement clock. In the absence of a difference in resistance values, the regulated power supply 10, controlled by logic device 9, generates a low voltage level sufficient to measure the resistance, and control attenuator 5 has a transmission coefficient of 1. In the first resistance measurement cycle, logic device 9 increases the voltage The power supply of the noise resistor I is controlled by the adjustable power supply 10. This operation is carried out without the arrival of a signal from the comparison circuit 8, in order to measure the resistance not distorted by interference in the first cycle, may be present immediately at the beginning of the measurement. At the end of the measurement cycle, the logic device 9 corrects the measurement if during the accumulation of the signal there was interference through the integrator zeroing circuit in channel 3 and opens the AND 4 circuit, passing the signal to the computing device 11. If interference occurs during the accumulation of the noise signal at a stationary temperature The impedance measurement channel also causes interference, which is manifested in an increase in the impedance measurement result. At the same time, in the second cycle, the comparison circuit 8 receives signals that are proportional to the measured resistances (,) -equalities of each other by the amount of interference. The comparison circuit 8, through the logic device 9, generates a signal to the adjustable power supply 10 for increases in n times the supply voltage, as well as a signal to the controlled attenuator 5 for a change in the gain times. As a result, in the third measurement step, the output voltage Uj is obtained at the output of the resistance meter with a reduced effect of interference.

nu. + iU whether

where and is the voltage without interference; uU - interference voltage

, Uj is the converted voltage with reduced interference action n times.

Next, an estimate of the difference (Uj - and) is made. Since there was no temperature change (Uj HU) is zero within the measurement error. Based on the measurement results of the resistances R i, and R., the magnitude of the interference is estimated. According to the results of measuring the temperature in the channel measuring the noise and the magnitude of the noise in the channel measuring the resistance, the obtained value of the absolute temperature (definable channel noise measurement) in the computing device 11 is corrected. At the end of the measurement, the logic device 9 generates a signal of the digital voltage feed through the zeroing circuit of the integrator in channel Z; the voltage of the accumulated noise voltage is proportional to the average square of the noise, and the measurement result of the noise channel is transmitted to the calculating device 11 by opening the circuit 4. At the change in temperature and the absence of interference when the circuit 8 detects the difference between the values of V and U logic device 9 generates a signal to the regulated power supply 10 for the power supply voltage to decrease by n times, as well as a signal to the controlled attenuator to change the coefficient transmission ienta (dividing the signal into n times). In this case, a voltage U occurs at the output of the resistance meter.

hCU.-tiU ,.

where - increase in voltage due to

temperature changes. Since there is a change in resistance due to the effect of temperature, there will be no difference between the second and third measure of resistance measurement. Estimating the difference (Ug-04) gives npRpameHtfe temperature

:di. In this case, the result of measuring the temperature through the channel measuring the resistance of the noise resistor enters the computing device. The logic device closes the AND circuit in order not to introduce an error into the measurement over the noise channel due to the nonstationary temperature. With the joint action of interference and non-stationary temperature, the operation process of the device is similar, i.e. the difference (U - U) is constantly detected

U, 2 ..U As a result of increasing the power supply and normalizing, the output of the resistance meter produces a voltage n (.i - Also, the difference. (Uj -up determines the temperature increment of dT-g, which is not allowed by the logic device 9) The noise channel signal to the computing device 11 is closed by the circuit 4. An evaluation of the difference (Ug - U) makes it possible to detect the interference. When combined with the action of the interference and changing the temperature scientific research institute, the inteztrator is nullified in channel 3 of the noise measurement and only after the action ps ends. chkhy logic The device 9 generates a null-Lenin termination signal. This is due to the difficulty of determining the magnitude of the correction signal at the end of the measurement with the simultaneous operation of the noise and changing the temperature. Since no noise signal accumulates in the noise channel 3, the logic device 9 does not generate a correction signal At the end of the interference, the integrator in the noise measurement channel 3 accumulates a signal. Thus, at times of unsteady temperatures, the temperature increment is measured along the measurement channel resistance, as the temperature stabilization - th channel for noise is performed estimate of the absolute temperature. Such a process

Claims (2)

measurement is necessary because of the significant dynamic error in measuring the transient temperature in the noise channel, which exceeds the measurement error in the temperature increment in the resistance measurement channel. As a result, a noise thermometer can work with the same accuracy in the presence of non-periodic interference pulses (which are characteristic of normal operating conditions), which allows to expand the scope of its application. & U Invention Noise Thermometer, which contained a noise resistor, a noise measurement channel, a noise resistor measurement channel, a computing device, an adjustable power source, characterized in that, in order to improve the measurement accuracy under non-periodic interference, an AND scheme is introduced , a logic device, a switch, the input of which is connected to a noise resistor, and the outputs - to the inputs of a measurement channel for the resistance of a noise resistor and a noise measurement channel, the output of which through circuit I is connected to a calculation It is a device, where the measurement of the resistance of the noise resistor contains a series-connected controlled attenuator and a resistance meter, the output of which is through the delay unit and directly connected to the inputs of the comparison circuit and the computing device, the input of the logic device is connected to the comparison circuit, and the outputs are connected respectively to a noise measurement channel, an AND circuit, a computing device controlled by an attenuator, and through an adjustable power source with a switch. Sources of information taken into account during the examination 1. USSR author's certificate 488093, cl. G 01 K 7/30, 1973. 2. Authors certificate of the USSR 446774, cl. G 01 K 7/30, 1972 (npoTOTJ n).