JPS6261161A - Measuring instrument for correlation function - Google Patents

Abstract

PURPOSE:To obtain a correlation function measuring instrument to be constituted of a simple and small circuit by starting a signal generating shift register in the 1st maximum period sequence from an initial value advanced from a signal generating shift register in the 2nd maximum period sequence by an initial value setter. CONSTITUTION:Since the mutual correlation functions are determined only by a relative time difference between the two functions, the signal generating shift registers 1, 7 for the 1st and 2nd maximum period sequences are formed and the shift register 1 is started from the initial value advanced from the shift register 2 by the initial value setter 8 though the two functions are ordinally delayed by a variable delay circuit. Consequently, the correlation function measuring instrument can be obtained by a small-sized and simple circuit.

Description

[Detailed Description of the Invention] [Summary] A correlation function measuring device includes a first and second maximum period sequence signal generation shift register, and an output of the first maximum period sequence signal generation shift register is connected to the target system. The output of the signal generation shift register for the second maximum period sequence is directly input to the multiplier on the output side of the target system, and the signal generation for the first maximum period sequence is performed by an initial value setting device. By starting the shift register from an initial value that is more advanced than the signal generation shift register of the second maximum cycle series, it is possible to realize this with a small-scale and simple circuit.

[Industrial application field]

In order to obtain the impulse response of the target system, the present invention
The present invention relates to an improvement of a correlation function measuring device that measures a correlation function of a pseudorandom signal of a maximum periodic sequence (hereinafter referred to as an M sequence).

It is desirable that the above-mentioned correlation function measuring device can be realized with a small-scale and simple circuit.

[Conventional technology]

FIG. 3 is a block diagram of a conventional correlation function measuring device.

In the figure, 1 is the M-series signal generation register, 2 is the target system,
3 is a variable delay circuit, 4 is a multiplier, 5 is an integration circuit, and 6 is a control circuit.

In FIG. 3, the M-sequence signal x (t) output from the M-sequence signal generation register 1 is input to the target system 2 for one period T by being controlled by the control circuit 6, and the output y (t ) is input to the multiplier 4, while the signal x (
t) to the variable delay circuit 3, obtain a signal x (-τ) delayed by the delay time τ, and input this to the multiplier 4,
The multiplication result is integrated over one period T by the integrating circuit 5, and the cross-correlation function Φ(τ)=y(t) x(-τ)dt
seek.

In this operation, the variable delay circuit 3 under the control of the control circuit 6 sequentially varies the delay time τ by 1 clock until the time of 1 period T is reached, obtains the cross-correlation function at each time, and calculates the impulse of the target system 2. Seeking a response.

[Problem that the invention seeks to solve]

However, in the case of Fig. 3, it is necessary to provide a wide range of delay in the variable delay circuit 3, so the variable delay circuit 3 becomes complicated and large-scale, and as a result, the circuit of the correlation function measuring device becomes complicated. There is also a large-scale problem.

[Means for solving problems]

The problem mentioned above is that in FIG. 1, the signal generation shift registers 1 and 7 of the first and second maximum period series are provided, and the output of the signal generation shift register 1 of the first maximum period sequence is transmitted to the target system 2. The output of the signal generation shift register 7 of the second maximum period sequence is input directly to the multiplier 34 on the output side of the target system 2, and the initial value setter 8 inputs the output of the signal generation shift register 7 of the second maximum period sequence. This problem is solved by the correlation function measuring device of the present invention, which starts the signal generation shift register 1 from an initial value that is advanced from the signal generation shift register 7 of the second maximum period series.

[Effect]

The present invention focuses on the fact that the cross-correlation function is determined only by the relative time difference between two functions, and in contrast to delaying using a variable delay circuit, the signal generation shift of the first and second maximum period series Registers 1 and 7 are provided, and an initial value setter 8 causes the signal generation shift register 1 of the first maximum period series to start from an initial value that is advanced from the signal generation shift register 7 of the second maximum period sequence. By doing so, the correlation function measuring device can be realized with a small-scale and simple circuit.

〔Example〕

First, to explain the principle of the present invention using the block diagram shown in FIG.
．． 7, the M-sequence signal generation register 1 is loaded with a value advanced by one clock from the M-series signal generation register 7 by the initial value setter 8 controlled by the control circuit 6', and the value for one cycle MT is loaded. , to the target system 2, and input the output to the multiplier 4. On the other hand, the output of the M-sequence signal generation register 7 is input to the multiplier 4 for one period T under the control of the control circuit 6', and the multiplication result is input to the multiplier 4. is integrated over one period T by an integrating circuit 5 to obtain a cross-correlation function.

The operation carried out by the initial value setter 8 is sequentially carried out by l clocks until a time of 3tIT for one cycle is reached, and the cross-correlation function at each time is obtained, and the impulse response of the target system 2 is obtained.

Next, an embodiment of a circuit for generating an advanced M-sequence signal will be described with reference to FIG.

FIG. 2 is a circuit diagram of an advanced M-sequence signal generator according to an embodiment of the present invention.

In the figure, 1 is the same M-series signal generation register as in the cases of FIGS. 1 and 3, 9 is an M-series signal generation register for initial value setting that inputs the same clock as M-series signal generation register 1,
13.15 to 18 are flip-flops, and 14.19 is an exclusive OR circuit.

Under the control of the control circuit 6'' shown in FIG.
Set the value to be one clock ahead.

When outputting signals from the M-sequence signal generation registers 1 and 7 in FIG. 1, the M-series signal generation register 1 is loaded with a value advanced by one clock. Outputs T minute signal.

Next, under the control of the control circuit 6', one clock is input to the M-series signal generation register 9 during this one cycle T, and two
This value is set as a value advanced by a clock, and this value is loaded into the M-sequence signal generation register 1, started, and a signal corresponding to one period T is outputted.

The above operation of advancing one clock at a time is one cycle T.
Do this until the time is reached.

The value of the M-sequence signal generation register 9 is loaded into the M-series signal generation register 1 by loading the outputs of the flip-flops 15 to 18 of the M-series signal generation register 9 to the flip-flops 10 to 13 of the M-series signal generation register 1. Loading data b: Connect to ζ child A, and under the control of the control circuit 6', data can be loaded by sending Rotoy No. 5 to the load terminals of the Pflosops 10 to 13.

As explained above, the advanced M-sequence signal generator can be configured with two M-series signal generation registers, so the black circuit is simpler and smaller in size than the variable delay circuit 3 of FIG.

Therefore, the correlation function measuring device can also be configured with a simple and small-scale circuit.

The initial value setter 8 in FIG. 1 is composed of a microcomputer, etc.
An initial value may be created and input to the M-sequence signal generation register 1.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to obtain a correlation function measuring device that can be configured with a simple and small-scale circuit.

[Brief explanation of drawings]

Fig. 1 is a principle block diagram of the correlation function measuring device of the present invention, Fig. 2 is a circuit diagram of an advanced M-sequence signal generator according to an embodiment of the present invention, and Fig. 3 is a block diagram of a conventional correlation function measuring device. It is a diagram. In the figure, 1.7.9 is the signal generation shift register of the maximum period series, 2 is the target system, 3 is the variable delay circuit, 4 is the multiplier, 5 is the integration circuit, 6.6゛ is the control circuit, and 8 is the initial stage. Value setter, 10 to 13. 15 to 18 are flip-flops, 14.1
9 indicates an exclusive OR circuit.

Claims (1)

[Claims] In order to obtain the impulse response of the target system (2), when measuring the correlation function of the pseudorandom signal of the maximum period sequence (M sequence), the signal generation shift of the first and second maximum period sequence Register (1
) (7), the first maximum period series signal generation shift register (1)
is input to the target system (2), and the output of the second maximum periodic sequence signal generation shift register (7) is
The signal generation shift register (1) of the first maximum period sequence is input directly to the multiplier (4) on the output side of the target system (2), and the signal generation shift register (1) of the first maximum period sequence is inputted directly to the multiplier (4) on the output side of the target system (2). A correlation function measuring device characterized in that it starts from an initial value advanced from a periodic series signal generation shift register (7).