JP2699832B2 - Signal detection processing circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal detection processing circuit for automatically detecting a pulse signal from a noise background.

[0002]

2. Description of the Related Art Conventionally, as a signal detection processing circuit of this type, one having a target detection circuit as shown in FIG. 3 (a) and one having a target detection circuit as shown in FIG. 4 (a) and FIG. There is a circuit including a moving average circuit and a target detection circuit. this house,
The signal detection processing circuit shown in FIG. 3A has a reference signal generation circuit 22 and a comparison circuit 24, and compares the input signal 21 with a reference signal (threshold) 23 from the reference signal generation circuit 22. As shown in FIG. 3B, signal detection for a target section 23 is performed from a portion where the input signal 21 exceeds the threshold value 23.

The signal detection processing circuit shown in FIGS. 4A and 5A is a moving average circuit 3 having a multiplication circuit 32, an addition circuit 33, a storage circuit 34 and a subtraction circuit 35.
At 0, a moving average value 36 of the input signal is obtained. Next, the output 36 is stored in the storage circuit 38 and the reference signal generation circuit 3.
9, a subtraction circuit 40 and a comparison circuit 41 are input to a target detection circuit 37. The subtraction circuit 40 subtracts the moving average value I _I- 144 before N samples from the input signal I _I. Is compared with a reference signal (threshold) 42 in a comparison circuit 41, and as a result of this comparison, a signal between sections exceeding the threshold is detected.

[0004]

However, FIG.
In the signal detection processing circuit shown in (a), a reflected wave section 26 due to an input signal other than the direct wave of the signal is formed following the target section 25, and the level fluctuation in the reflected wave section 26 is large. It was detected as a signal and erroneous detection 27 occurred frequently.

As a countermeasure against this, FIGS. 4A and 5
The signal detection processing circuit of (a) is effective, and accurately detects a short pulse signal. However, for a signal having a pulse width exceeding the moving average time constant, it is difficult to accurately determine the pulse width, and there has been a problem that the signal length of the signal cannot be accurately detected.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an object to accurately detect a signal end position for a signal in which a direct wave and a reflected wave are mixed, and to accurately detect a signal length. It is intended to provide a detection processing circuit.

[0007]

In order to achieve the above object, a signal detection processing circuit according to the present invention performs a moving average on an input signal by a fixed window for each sample and outputs a moving average value. An averaging circuit, a storage circuit that holds the moving average value, a subtraction circuit that calculates a difference output between an input signal and a moving average value N samples before held in the storage circuit, A reference signal generating circuit for setting a first threshold value multiplied by an arbitrary constant and a second threshold value obtained by multiplying a moving average value N samples before detection by another constant at the time of detection; Is compared with the difference output from the subtraction circuit outside the target detection section, and when the difference output exceeds the first threshold, the control signal is used as the target detection and the moving average is calculated. To the circuit to stop the moving average. , Said second threshold value from the reference generator circuit and a difference output from the subtraction circuit and <br/> compared within the target detection range, target detection when the difference output becomes equal to or less than the second threshold value At the end, a comparison circuit outputs a control signal to the moving average circuit to restart the moving average. Preferably, the reference signal generating circuit sets a first threshold value obtained by multiplying a moving average value by an arbitrary constant, and multiplies the moving average value N samples before detection by another constant at the time of detection. And two circuits for setting the second threshold value.

[0008]

The signal detection processing circuit having the above configuration compares the output (difference output) from the subtraction circuit with the first threshold value, and if the difference output exceeds the first threshold value, moves to the moving average circuit. A control signal for stopping the averaging is output, and a second threshold value is set and compared with the input signal. When the signal becomes equal to or less than the second threshold value, the target detection is terminated, and the moving average circuit is restarted. A control signal to be output is output.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram of a signal detection processing circuit according to the present embodiment, and FIG. 2 is a signal waveform diagram during operation. The signal detection processing circuit includes a moving average circuit 1, a storage circuit 2, a subtraction circuit 3, a reference signal generation circuit 4, and a comparison circuit 5 from the input side.

The moving average circuit 1 has the same configuration as that shown in FIG. 4 (a), and performs a moving average on the input signal 6 by a fixed window for each sample.
The moving average value 7 is output. The storage circuit 2 is a moving average circuit 1
Are sequentially stored and held.
The subtraction circuit 3 calculates a difference output 9 by subtracting the input signal 6 and the moving average value N samples before the detection held in the storage circuit 2. The reference signal generation circuit 4 sets and outputs a first threshold value obtained by multiplying the moving average value by an arbitrary constant, and multiplies the moving average value N samples before detection by another constant at the time of detection. The second threshold value is set and output.

The comparison circuit 5 has a first threshold value 11 from the reference signal generation circuit 4 and a difference output 9 calculated by the subtraction circuit 3.
Are compared (see FIG. 2). And this comparison circuit 5
When the difference output 9 exceeds the first threshold value 11, the control signal 10 is sent to the moving average circuit 1 to stop the moving average as target detection. The comparison circuit 5 includes a reference signal generation circuit 4
Is compared with the difference output 9 calculated by the subtraction circuit 3 (see FIG. 2). Then, when the difference output 9 becomes equal to or less than the second threshold value 12, the target detection is terminated, and the moving average circuit 1 controls the moving average circuit 1 to restart the moving average.
Outputs 0.

Thereafter, this is repeated to detect a pulse signal. In these operations, as shown in FIG. 2, the target detection process is performed by comparing the difference output 9 with the first threshold value 11 in a section other than the target detection section 13. In the target detection section 13, a target end determination process is performed by comparing the input signal 6 with the second threshold value 12.

The reference signal generation circuit 4 sets a first threshold value obtained by multiplying the moving average value by an arbitrary constant, and adds another constant to the moving average value N samples before detection. It may be constituted by two circuits for setting the multiplied second threshold value.

[0014]

As described above, according to the present invention, until the target is detected, a signal is detected when the signal exceeds the first threshold, and once the signal is detected, the second threshold is reset. The target end determination process is performed by setting the target end position of a signal in which a direct wave and a reflected wave are mixed, and the signal length can be accurately detected. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram of a signal detection processing circuit according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram during the operation of the above.

3A is a block diagram of a conventional signal detection processing circuit, and FIG. 3B is a signal waveform diagram of the circuit.

FIG. 4A is a block diagram of a signal detection processing circuit including a conventional moving average circuit, and FIG. 4B is a signal waveform diagram of the circuit.

5A is a block diagram of a signal detection processing circuit provided with a conventional moving average circuit, and FIG. 5B is a signal waveform diagram of the circuit.

[Explanation of symbols]

 Reference Signs List 1 moving average circuit 2 storage circuit 3 subtraction circuit 4 reference signal generation circuit 5 comparison circuit 6 input signal 7 moving average value 8 moving average value before N samples 9 difference output 10 control signal

Claims (2)

(57) [Claims] 1. A moving average circuit for performing a moving average on an input signal by a fixed window for each sample and outputting a moving average value, a storage circuit for holding the moving average value, an input signal and the storage A subtraction circuit for calculating a difference output from the moving average value N samples before the circuit held; a first threshold value obtained by multiplying the moving average value by an arbitrary constant; A reference signal generation circuit for setting a second threshold value obtained by multiplying the moving average value by another constant; and a first threshold value from the reference signal generation circuit and a difference output from the subtraction circuit outside a target detection section. Comparing, when the difference output exceeds the first threshold value, sending a control signal as a target detection to the moving average circuit to stop the moving average, and also, from the difference output from the subtraction circuit and the reference generation circuit, eyes a second threshold value of Compared in the detection zone, as a target detection ends when the difference output becomes equal to or less than the second threshold value, that is constituted by a comparator circuit for outputting a control signal to resume the moving average to the moving average circuit Characteristic signal detection processing circuit. 2. The circuit according to claim 1, wherein the reference signal generation circuit sets a first threshold value obtained by multiplying a moving average value by an arbitrary constant, and multiplies the moving average value N samples before detection by another constant. 2. The signal detection processing circuit according to claim 1, comprising two circuits for setting the second threshold value.