JPH0486997A - Filter circuit - Google Patents

Abstract

PURPOSE:To secure a quick responsiveness by finding frequencies from the average movement of periodic signals outputted from a period measuring section in time series and a mean frequency from the found frequencies, and then generating an output proportional to the output signal of the mean frequency. CONSTITUTION:A period measuring section 3 measures periods Tn of input signals fn at every edge of the signals fn by using a clock ck. A period averaging circuit 5 finds a mean period T0 by taking the sum of past m+1 pieces of periods Tn and dividing the sum by m+1 synchronously to the measurement by the section 3 and stores the mean period in a register 6. The circuit 5, on the other hand, samples mean periods T0 at fixed time intervals Ts asynchronously to the measurement and finds frequencies Fa by means of an inverse operation circuit 8. Then the circuit 5 takes are sum of the n+1 pieces of the so far found frequencies Fa and finds a mean frequency F0 by dividing the sum by n+1 by means of a frequency averaging circuit 10. A drive circuit 11 decides a deflection angle against the value of the found mean frequency F0 and drives an analog meter 12.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a filter circuit for a system that measures periods and drives an analog meter.

[Conventional technology]

Examples of conventional filter circuits include those shown in FIGS. 3 and 4. In Fig. 3, l is a pulse count type counter, and this counter 1 is a sensor (
(not shown) counts the detected input frequency f for a certain gate time T. That is, in the pulse counting method, as shown in FIG. 5(a), the count result of the input frequency f input to the counter 1 during the time Ts from the rise to the fall of the gate signal (pulse) is used as the measurement value output by the analog meter. This is a signal processing method that drives the In addition, in FIG. 4, 2 is a period measurement method counter, and this counter 2 is a period time T of an input signal f that a sensor (not shown) detects a clock signal ck of a constant frequency.
It counts only s. As shown in FIG. 5(b), the period measurement method is a signal processing method in which the clock signal ck input during the period T8 of the input signal f is counted and the result of counting is used as a measurement value to drive an analog meter.

[Problem to be solved by the invention]

However, in the conventional filter circuit shown in Fig. 3, since the input frequency is integrated, the stylus runout (sampling error) against frequency fluctuations (periodic fluctuations) is small, but the responsiveness is limited by the gate time. Therefore, there was a problem in that the response was slow when the handled frequencies were low. In addition, in the conventional filter circuit shown in Fig. 4, data is updated every cycle of the input frequency, so the response is fast, but if there is a periodic fluctuation (see Fig. 5 (1)), There was a problem that needle runout (sampling error) occurred. This invention was made in order to solve the above problems.It ensures quick response through period measurement, prevents sampling errors, and furthermore performs averaging processing after converting the period to frequency. The purpose is to obtain a filter circuit that provides

[Means to solve the problem]

The filter circuit according to the present invention includes a period measuring section that calculates the period of the pulse signal output from the sensor, a period averaging processing circuit that calculates the moving average of the periodic signal outputted in time series from the period measuring section, and A frequency calculation circuit that calculates the frequency with respect to the period average by inversely calculating the period average obtained by the period average processing circuit, a frequency averaging processing circuit that calculates the frequency average of the output signal from this frequency calculation circuit, and this frequency averaging processing. It consists of a drive circuit that generates an output proportional to the output signal of the circuit and determines the deflection angle.

[Effect]

The filter circuit in this invention determines the period of the pulse signal output from the sensor by a period measuring section, calculates a moving average of the periodic signal outputted in time series from this period measuring section, and back-calculates the determined period average. , find the frequency for the periodic average, calculate the frequency average from the calculated frequency, generate an output proportional to the output signal, determine the deflection angle, and drive the meter to ensure quick response. In addition to preventing sampling errors, frequency averaging provides appropriate responsiveness and smooth movement.

【Example】

Hereinafter, the present invention will be explained in detail based on the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a first flowchart. First, to explain the configuration, 3 is a period measuring section for the input signal f7, 4 is a shift register that holds m+1 pieces of data whose period has been measured by the period measuring section 3, and 5 is a shift register that holds m+1 pieces of data held by the shift register 4. A cycle averaging processing circuit which adds the sum and divides the result by m+1; 6 is a cycle averaging processing circuit 50 and a cycle averaging T; The period measurement unit 3, shift register 4, period averaging processing circuit 5, and register 6 constitute a period filter 7. Reference numeral 8 denotes an inverse calculation circuit which is a frequency calculation circuit that samples the period T0 at fixed time intervals Ts and converts it into a frequency Fa; 9 a shift register that holds the calculation result of the inversion circuit 8; lO
adds n frequencies held by shift register 9,
A frequency averaging processing circuit that divides the result by n, 11
is the frequency average F from the frequency averaging processing circuit 10. The frequency filter 13 is a drive circuit that generates an output proportional to , and drives the analog meter 12. The inverse calculation circuit 8, the shift register 9, the period averaging circuit 0, and the drive circuit II constitute a frequency filter 13. Next, the operation will be explained. First, the cycle measuring section 3 measures the cycle T1 for each edge of the input signal f7 using the clock ck. In synchronization with this cycle measurement, the cycle averaging processing circuit 5 calculates the past m+1
The period T7 is added, the result is divided by m, +1, and period averaging processing is performed to obtain the period average T0. This result is stored in register 6. On the other hand, asynchronously, the cycle average T
0 is sampled, and the period is inversely calculated by the inverse calculation circuit 8 to obtain the frequency F. Then, the n+1 frequencies F1 obtained so far are added, and the result is divided by n+1 by the frequency averaging processing circuit 10 to perform averaging processing to obtain the frequency average F0. The drive circuit 11 uses the determined frequency average F0
The deflection angle is determined based on the value of , and the analog meter 12 is driven. In the above embodiment, the period average T is determined by the period average processing circuit 5. , but m m may also be used. Further, in the above embodiment, the frequency average F is determined by the frequency averaging processing circuit 10. , but n n may also be used.

【Effect of the invention】

As explained above, according to the present invention, the configuration includes a period measuring section that calculates the period of the pulse signal output from the sensor, and a moving average of the periodic signal outputted in time series from the period measuring section. A period averaging processing circuit, a frequency calculation circuit that calculates the frequency with respect to the period average by inversely calculating the period average obtained by this period averaging processing circuit, and a frequency averaging process that calculates the frequency average of the output signal from this frequency calculation circuit. The drive circuit generates an output proportional to the output signal of the frequency averaging processing circuit and determines the deflection angle, making it possible to improve responsiveness through periodic measurement and eliminate sampling errors caused by averaging periodic data. prevent,
The effects of frequency averaging enable appropriate responsiveness and smooth movement.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flowchart explaining the operation of FIG. 1, FIG. 3 is a block diagram showing an example of a conventional filter circuit, and FIG. A block diagram showing another example of a filter circuit, FIG.
a) is a flowchart explaining the operation of FIG.
b) is a flowchart explaining the operation of FIG. 4; 3...Period measurement unit 5...Period averaging processing circuit 8...Frequency calculation circuit 10...Frequency averaging processing circuit 11...Drive circuit

Claims (1)

[Claims] A period measuring section (3) that calculates the period of the pulse signal output from the sensor, and a period averaging processing circuit (3) that calculates the moving average of the periodic signal outputted in time series from the period measuring section (3).
5), a frequency calculation circuit (8) that calculates the frequency with respect to the period average by inversely calculating the period average obtained by this period average processing circuit, and a frequency averaging process that calculates the frequency average of the output signal from this frequency calculation circuit. A filter circuit comprising a circuit (10) and a drive circuit (11) that generates an output proportional to the output signal of the frequency averaging processing circuit and determines the deflection angle.