JPS6227682A - Microwave range finder - Google Patents

Abstract

PURPOSE:To enable proper measurement not affected by the change in a surface to be measured, by making a threshold value variable or setting the same corresponding to the amplitude of a beat signal. CONSTITUTION:The reflected wave from a surface to be measured is received by a microwave circuit 1 to detect a beat signal and the cycle of the beat signal is measured by a frequency count circuit 3 while the measured beat cycle Tb is sent to a range operation circuit 4. A measuring range Ri is calculated from the cycle Tb by the circuit 4 to be temporarily stored in a first memory circuit 5 and the previous measured range data Ri-1 is not only temporarily stored in a second memory circuit 6 but also outputted to a subtractor 7. The subtractor 7 subtracts the output Ri-1 of the circuit 6 from the output Ri of the circuit 5 to operate the change quantity DELTAR of the measuring range. An absolute value operation circuit 8 calculates ¦DELTAR¦ of the change quantity DELTAR to output the same to a comparator 11. A threshold operation circuit 10 sets a threshold value Rth from the output of a full wave rectifier circuit 9 and level change quantity and the threshold value Rth is compared with the absolute value DELTAR by the comparator 11. When the absolute value DELTAR is within the threshold valve, the order receiving the data Ri of the circuit 5 is outputted to the circuit 6 and the data Ri-1 of the circuit 6 is altered to Ri.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention emits frequency-modulated microwaves to a surface to be measured, and detects the beats obtained by mixing and detecting a part of the emitted waves and the reflected waves. The present invention relates to a microwave distance measuring device that measures the distance from a signal to a surface to be measured.

[Conventional technology]

Conventionally, when measuring the received pig iron level of a torpedo car during hot metal pretreatment at the blast furnace hearth using an FM-GW microwave distance measurement device, past data is saved and compared with current measurement data to improve accuracy. If the amount of change, which is the difference, is larger than a threshold (fixed value), the current data is excluded and not output as a measured value.

[Problem that the invention seeks to solve]

When this conventional microwave pressure # measurement position is used for level measurement during hot metal pretreatment, especially during desiliconization, a large amount of slag is generated on the top of the hot metal and its fluctuation is large, so as shown in Figure 3. , the level fluctuation measurement increases with the layer thickness l of the slag, and if the threshold value is small, it becomes impossible to measure. If the threshold value is increased to prevent this, the accuracy will be lowered when the slag is small, making it impossible to perform proper measurements.

[Means for solving problems]

The present invention has a relationship as shown in FIG. 2 between the layer thickness l of the slag generated on the top of the hot metal and the microwave reception power (beat signal amplitude) (beat signal amplitude V as the slag layer thickness l increases). The threshold value can be set according to the beat signal amplitude by taking advantage of the fact that the slag layer thickness l and the level change ratio have a relationship as shown in Figure 3, as mentioned above. Variable settings allow changes in the surface to be measured (
This enables proper measurement regardless of the presence or absence of slag generation.

That is, the microwave distance measuring device of the present invention is characterized by including a threshold calculation circuit that varies and sets the threshold according to the amplitude of the beat signal.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the microwave distance measuring device of the present invention.

The microwave circuit l emits frequency-modulated microwaves, receives reflected waves from the surface to be measured, and detects a beat signal.
Send to amplifier circuit 2. The period counting circuit 3 receives the beat signal amplified by the amplifier circuit 2, measures the period of the bee signal, and sends it to the distance calculation circuit 4. In the distance calculation circuit 4, the measurement data of eight people is temporarily stored in the memory circuit 5 of the beat period Tb 1. Second memory circuit 6
Then, the previous measurement data Rj-1 is temporarily stored and output as distance data, and this data is further output to the subtracter 7. The subtracter 7 receives the output R of the first memory 5.
The output Rλ-/ of the second memory 6 is subtracted from λ to calculate the amount of change ΔR in the measured distance. The absolute value calculation circuit 8 receives the output of the subtracter 7 and calculates the absolute value 1ΔR of the change iR in the measured distance.
1 is obtained and output to the comparator 11. The aftermath rectifier circuit 9 rectifies the beat signal amplified by the amplifier circuit 2. The threshold calculation circuit 10 calculates the output of the aftereffect rectification circuit 9 and the level fluctuation as shown in FIGS. 2 and 3.
is a constant), the threshold value Rd can be calculated using the formula Rd=A
/V (A is a constant). B in comparator 11
=R, c-lΔR1 is calculated, and when B>0, that is, when the absolute value ΔR is within the threshold RTH, the second memory 6
A transfer command for receiving the output data R, - of the first memory 5 is output to the first memory 5. As a result, the data Rλ-l of the second memory circuit 6 becomes Rλ and is output to the outside.

〔Effect of the invention〕

As explained above, the present invention has the advantage that by varying and setting the threshold value according to the beat signal amplitude, it is possible to perform appropriate measurement regardless of changes in the surface to be measured.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the microwave distance measuring device of the present invention, Fig. 2 is a graph showing the relationship between the slag layer thickness l and the beat signal amplitude Vb, and Fig. 3 is a graph showing the relationship between the slag layer thickness l and the beat signal amplitude Vb. It is a graph showing the relationship between level change measurements. 1: Microwave circuit, 2: Amplification circuit, 3: Period counting circuit, 4: Distance calculation circuit, 5: First memory circuit, 6: Second memory circuit, 7: Subtractor, 8: Absolute value calculation circuit , 9: Full-wave rectifier circuit, 10: Threshold calculation circuit, 11: Comparator,
T: beat period, Rλ: currently measured distance. Re-I: past distance data, ΔR: amount of change in measured distance. R: Threshold.

Claims (1)

[Claims] A frequency-modulated microwave is radiated to a surface to be measured, and a portion of the radiated wave and a reflected wave are mixed and detected, and the distance from the beat signal to the surface to be measured is measured, Microwave distance measurement that saves past distance data and excludes the currently measured data from being output as a measured value when the amount of change from the currently measured distance data is greater than a certain threshold What is claimed is: 1. A microwave distance measuring device comprising: a threshold calculation circuit that varies and sets the threshold according to the amplitude of the beat signal.