JPH0465678A - Waveform display device - Google Patents

Abstract

PURPOSE:To decrease a truncation error when (n) equally divided interpolation data in an input data sequence are calculated by performing interpolation between adjacent data points in the forward and backward directions of a time base by plural interpolation data sequence arithmetic means which are cascaded. CONSTITUTION:An analog input signal which is applied to an input terminal 1 is applied to an FIFO memory 5 through an A/D converter 2. Output data of respective taps of this memory 5 are applied to a weight coefficient multiplier sequence 6 for calculating interpolation data in the forward direction and also applied to a weight coefficient multiplier sequence 11 for calculating interpolation data in the backward direction. The output data of the final stage of the memory 5 is applied to a data memory 3. The output signal of the coefficient multiplier sequence 6 is added by an adder 7 in the forward direction and its addition output signal is applied to an FIFO memory 8. Output data of respective taps of the memory 8 are applied to a weight coefficient multiplier sequence 9, whose output signal is added by an adder 10, whose output is applied to the memory 3. The output data of the final stage of the memory 8 is applied to the memory 3. The processing of data in the backward direction is the same.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a waveform display device, and more particularly to an improvement in data interpolation display.

<Prior art> A type of waveform display device samples an analog input signal waveform, converts it to digital waveform data, stores it in a memory, reads out the waveform data stored in the memory as needed, and displays it on a display section. There are digital devices designed to reproduce and display waveforms.

However, in such a waveform display device, if the sample data per cycle of the analog input signal is small, the analog input signal cannot be accurately reproduced and displayed using only the waveform data stored in the memory.

Therefore, in the conventional device, for example,
As described in Publication No. 3, interpolated data is calculated by multiplying the sampled waveform data by a weighting coefficient in the form of sinχ/χ and calculating the sum, and the waveform is reproduced using the sampled data and these interpolated data. The display is performed (V).

<Problem to be solved by the invention> However, although this method theoretically allows accurate data interpolation by calculating from an infinite number of sampled data, in reality A truncation error occurs because the calculation is performed after truncating the sampling data. In particular, when interpolating the midpoint of the sampling data, the truncation error becomes large because the weighting coefficient does not attenuate easily.

Furthermore, in order to calculate a plurality of interpolation points between sampling data, different weighting coefficient sequences must be prepared depending on the distance between the interpolation point and the data point.

The present invention focuses on such points, and its purpose is to reduce the truncation error when calculating n-equally interpolated data of an input data sequence using a weighting coefficient in the form of sinχ/χ, and to Another object of the present invention is to provide a waveform display device having an interpolation function that can perform interpolation with different distances between interpolation points and data points using the same weighting coefficient sequence.

<Means for Solving the Problems> The waveform display device of the present invention has a weighting coefficient in the form of sinχ/χ and is configured to calculate a 1/n interpolated data string from an input data string,
A plurality of first interpolation data strings in which the number of stages necessary for forward interpolation to the intermediate point of adjacent input data points are connected in cascade.
calculation means, weighting coefficients arranged in reverse order to the first interpolation data string calculation means, configured to calculate an interpolation data string (n-1>1/n) from the input data string; and a plurality of first and second interpolation data string calculation means in which the number of stages necessary for backward interpolation to the intermediate point of an input data point are connected in cascade, and the input data string and output data of each of these interpolation data string calculation means is provided. It is characterized by generating display waveform data based on columns.

In the present invention, forward interpolation between adjacent data points along the forward direction of the time axis is performed by a plurality of cascade-connected first interpolation data string calculation means, and interpolation along the backward direction is performed by a plurality of cascade-connected second interpolation data string calculation means.

<Embodiments> Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In FIG. 1, an analog input signal applied to an input terminal 1 is converted into a digital signal by an A/D converter 2. In FIG. The digital signal output from the A/D converter 2 is 11
The cascaded digital filters AI, A2 are added to the cascaded digital filters B1 . B
2 and is also added to data memory 3.

Moreover, each □ digital filter At, A2 . Bl.

The output data of B2 is also added to the data memory 3. This: Soldering iron, digital filter A1. A2 is Sjnχ
It has a weighting coefficient of the form /χ, and the input data string is 1 /
It is configured to calculate n interpolated data strings, and is used as a plurality of first interpolated data string calculating means in which the number of stages necessary for forward interpolation to the intermediate point of adjacent input data points are connected in cascade. In addition, digital filter B1. B2
has weighting coefficients in the opposite order to those of the first interpolated data string calculation means, and is configured to calculate an interpolated data string of (n-111"/n) from the input data string, and A plurality of second interpolation data strings in which the number of stages required to backward interpolate backward to a point are connected in cascade are used as calculation means.The input data of each interpolation data string calculation means stored in this data memory 3 □ Waveform data displayed on the display section 4 is generated based on the column and the output data column.

FIG. 2 is a diagram showing a specific example of FIG. 1, and shows an example in which interpolated data that divides adjacent sampling data into five equal parts is calculated using an 8-tap digital filter. The digital filter A1 is composed of a FIFO memory 5, a weighting coefficient array 6 that provides a weighting coefficient sequence, and an adder 7, and the digital filter A2 is composed of a FIFO memory 8, a weighting coefficient array that provides a weighting coefficient sequence, and an adder 10. The digital filter B1 is composed of a FIFO memory 5, a weighting coefficient array 11 that provides a weighting coefficient sequence, and an adder 12, and the digital filter B2 includes a FIFO memory 13 and a weighting coefficient array 14 that provides a weighting coefficient sequence. and an adder 15. Here, the weighting coefficient arrays 6.9 and 11.14 have coefficients arranged in reverse order.

FIG. 3 is an explanatory diagram of a weighting coefficient sequence, and shows a case where sampling data is interpolated at intervals of 1/10. In the case of an 8-tap type, the weight of each weighting coefficient unit is set to 1 to 8.

FIG. 4 is an explanatory diagram when data interpolation is performed using the weighting coefficient sequence shown in FIG. 3. In FIG. 4, the O mark indicates a sampling data string, the Δ mark indicates a 1/10 interpolated data string, the mark indicates a 2/10 interpolated data string, and the .mark indicates a 9/10 interpolated data string.
It shows an interpolated data string. Note that between adjacent sampling data, a direction A toward the midpoint along the time axis direction is defined as forward interpolation, and a direction B toward the midpoint along the direction opposite to the time axis direction is defined as backward interpolation.

The operation shown in FIG. 2 will be explained.

An analog input signal applied to input terminal 1 is converted into a digital signal by A/D converter 2 and applied to FTFO memory 5. The output data of each tap of the FIFO memory 5 is added to a weighting coefficient array 6 for calculating interpolated data in the forward direction, and is also added to a weighting coefficient array 11 for calculating interpolated data in the backward direction. In addition, F
The output data of the final stage of the IFO memory 5 is added to the data memory 3 as a sampling pig. In the forward direction, the output signals of the weighting coefficient array 6 are added by an adder 7,
This addition output signal is stored in the FIFO memory 8 as interpolated data.
added to. The output data of each tap of this FIFO memory 8 is added to a weighting coefficient array 9 for calculating the next interpolated data, and the output signals of this weighting coefficient array 9 are added in an adder 10 and data as interpolated data. Added to memory 3. Note that the output data of the final stage of the FIFO memory 8 is added to the data memory 3 as interpolation data. In the backward direction, the output signals of the weighting coefficient array 11 are added by an adder 12, and this added output signal is added to the FIFO memory 13 as interpolation data. The output data of each tap of this FIFO memory 13 is added to a weighting coefficient array 14 for calculating the next interpolated data, and the output signals of this weighting coefficient array 14 are added in an adder 15 to form interpolated data. Added to memory 3. Note that the output data of the final stage of the FIFO memory 13 is also added to the data memory 3 as interpolation data.

With this configuration, since the interpolation point is close to the sampling data point, the weighting coefficient sequence attenuates quickly, and the truncation error of the digital filter calculation becomes small. Further, interpolated data at different interpolation points can be obtained while using digital filters with the same configuration, which facilitates circuit design.

Note that each digital filter used in the present invention may be realized by software.

<Effects of the Invention> As explained above, according to the present invention, the truncation error when calculating n-equal interpolation data of an input data string using a weighting coefficient in the form of sinχ/χ is reduced, and
A waveform display device with an interpolation function that can perform interpolation with different distances between interpolation points and data points using the same weighting coefficient sequence can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a specific example of FIG. 1, FIG. 3 is an explanatory diagram of a weighting coefficient sequence, and FIG.
The figure is an explanatory diagram when data interpolation is performed using the weighting coefficient sequence of FIG. 3.

Claims (1)

[Claims] It has a weighting coefficient in the form of sinχ/χ, is configured to calculate a 1/n interpolated data string from an input data string, and performs forward interpolation to a midpoint between adjacent input data points. a plurality of first interpolation data string calculation means in which the number of stages necessary for /n interpolated data strings, and includes a plurality of second interpolated data string calculation means in which the number of stages necessary for backward interpolation to the intermediate point of adjacent input data points are connected in cascade. , A waveform display device characterized in that display waveform data is generated based on the input data string and output data string of each of these interpolated data string calculation means.