JPH0130405B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a processing device for signals output from measuring instruments that monitor information such as various flow rates and concentrations.

The output signal of the above-mentioned measuring device is normally transmitted as a DC voltage or DC current signal to a storage device, a printing device, a monitoring device, a control device, etc. Although these signals are input to the above-mentioned apparatus, not all of these signals are necessarily signals from the object to be measured, and signals due to disturbances occurring in the transmission line may be mixed together. Therefore, there is a high possibility that various devices may malfunction due to signals such as disturbances. The above-mentioned disturbances include, for example, firstly, disturbances caused by the influence of power supplies and signals from other systems, and secondly, disturbances related to the principles of measuring instruments, etc.

The first disturbance includes, for example, a high frequency wave that enters from a power source of a measuring instrument or the like. When a disturbance occurs due to this, it becomes a factor that causes the output signal of the measuring instrument to fluctuate little by little. Next, the second disturbance includes, for example, a measuring device that uses scattered light. When measuring the amount of light from a scattering hole, if light enters between the measuring device and the object to be measured, the measured value obtained will include light as a disturbance in addition to the scattered light from the object to be measured. The value is .
In addition, in situations where there is a substance that blocks light between the measuring instrument and the object to be measured, whenever such a substance gets into the space between the measuring instrument and the object to be measured, , the method of scattering changes. This is a disturbance caused by the use of light beams as the detection principle. Since an amplifier circuit is usually built into a measuring instrument, there is a possibility that the output signal may fluctuate greatly due to the above-mentioned disturbance in some cases.

As mentioned above, the presence of disturbances causes erroneous measured values, and therefore various countermeasures are normally taken against these disturbances. For example, in response to the first disturbance, there is a means of providing a circuit that intentionally delays the response by adjusting the time constant in order to eliminate the high frequency waves that enter from the power supply, thereby achieving stabilization. However, if the time constant is made too long, there is a drawback that the responsiveness decreases.
In addition, with respect to the second disturbance, for example, the environmental conditions under which the measuring instrument is used are adjusted, the usage conditions are limited, etc., so that disturbances related to the principle etc. do not occur. However, if a situation in which light rays are intermittently incident or blocked is unavoidable, it is difficult in principle to separate this disturbance.

For this reason, in recent years, in order to remove the first and second disturbances, means have been developed to digitally process the disturbances. First, for the first disturbance, digital signals obtained by sampling at fixed time intervals (hereinafter referred to as sampling data) are stored in memory, and an average value is calculated for a fixed number of sampling data up to the current time. There is a means. Also, a so-called moving average method is often used in which data is updated every time sampling data is obtained. This moving average value method can be expressed as follows. If the sampling interval of the digital signal is Δt, the current time is t, and the number of data is N, then = 1/N (x _t-(o-1)

Claims (1)

[Claims] 1. A conversion unit that converts a fluctuating analog data signal into a digital data signal and outputs it, and a smoothed value Yn that is the expected value of the data to be obtained.
A storage unit outputs the smoothed value Y _o-1 of number 1, and the smoothed value Y _o-1 output from this storage unit and the output signal of the conversion unit are input and compared, and the upper and lower limits of the output signal are determined. an input value smoothing value comparison section that sets a range and sends out only output signals within the range; an input value coefficient multiplication section that multiplies the output signal of this comparison section by a coefficient a; and an input value coefficient multiplication section that outputs from the storage section. Smoothed value Y _o-1
is input, and a smoothing value coefficient multiplication unit multiplies this value by a coefficient (1-a), and the output signal of this multiplication unit and the output signal of the input value coefficient multiplication unit are input, added, and output. A smoothed value calculation unit and an output signal calculated by this calculation unit are input, and when the output signal of the conversion unit is within the range set by the comparison unit, the output signal of the calculation unit is stored as a smoothed value. When the output signal of the conversion section is outside the range set by the comparison section, the output signal of the calculation section is not supplied to the storage section, and the smoothed value obtained is the previous smoothed value. A signal processing device comprising a digital-to-analog converter in which values are held.