JPH03251779A - Apparatus for correcting noise level - Google Patents

Abstract

PURPOSE:To always hold a constant noise level even when transmission pulse width is different by holding a noise level average value corresponding to transmission pulse width and using the same to calculate a noise level correction value. CONSTITUTION:During a noise level correcting period, a noise sampling circuit 1 performs the addition averaging of noise in matching relation to noise sampling timing. This average value is calculated at every transmission pulse width and held to data holding circuits 2a, 2b by transmission width. Subsequently, the noise level correction value corresponding to transmission pulse width is selected by a data change-over switch 3 and divided by a noise level reference value 5 to calculate a noise level correction value. This correction value is multiplied by a receiving signal by a multiplying circuit 6 and a noise level is kept constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radar device, and particularly to a noise level correction device thereof.

[Conventional technology]

Fig. 3 is a block diagram of a conventionally used noise level correction device. In Fig. 0, 1 is a noise sample circuit;
is the output of noise sample circuit 1 and the noise level reference value 5
A division circuit 6 calculates a noise level correction value by dividing the received signal, and a multiplication circuit 6 corrects the noise level by multiplying the received signal by the correction value.

Next, the operation will be explained. During the noise level correction period, the noise sampling circuit 1 adds and averages the noise in accordance with the noise sampling timing. Thereby, the noise level average value during the noise level correction period is calculated. Next, in the division circuit 4, the average value of the noise level is divided by the noise level reference value 5 to calculate a noise level correction value.

This correction value is multiplied by the received signal in the multiplication circuit 6 to correct the noise level.

[Problem to be solved by the invention]

Since the conventional noise level correction device is configured as described above, in a radar equipped with two types of distributed delay circuits for pulse compression corresponding to the transmission pulse width as shown in Fig. 4, the transmission pulse width Therefore, the receiving system is different, and therefore the noise level fluctuates depending on the transmission pulse width. Therefore, the conventional noise level correction device that does not have a noise level correction value on the transmission pulse width side has a problem in that it cannot correct noise level fluctuations due to the transmission pulse.

This invention was made to solve the above-mentioned problems, and it is possible to maintain a constant noise level even if the receiving system changes depending on the transmission pulse width in pulse compression radar and the noise level changes. The purpose is to obtain a correction device.

[Means to solve the problem]

The noise level correction circuit according to the present invention obtains a noise level correction value on the transmission pulse width side, and uses this value to correct the noise level.

[Effect]

Since the noise level correction circuit according to the present invention is configured as described above, it always maintains a constant noise level even if the level changes.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a noise level correction device according to an embodiment of the present invention, in which 1 is a noise sample circuit, 2a and 2
b is a data holding circuit that holds the output of the noise sample circuit l on the transmission pulse width side, 3 is a switch that switches the noise sample data held on the transmission pulse width side, and 4 is the output of the switch 3 and the noise level reference value 5. a division circuit that calculates a noise level correction value by dividing 6
is a multiplication circuit that multiplies the received signal by a correction value.

Next, the operation will be explained. During the noise level correction period,
The noise sample circuit 1 averages the noise in accordance with the noise sample timing.

This calculates the average value of the noise level. This average value is calculated for each transmission pulse width and is held on the transmission pulse width side by the data holding circuit 2a or 2b. Next, the noise level correction value corresponding to the transmission pulse width is selected by the data changeover switch 3, and the noise level correction value is calculated by dividing by the noise level reference value 5. This correction value is multiplied by the received signal by the multiplier circuit 6 to keep the noise level constant.

Note that in the above embodiment, there are two types of transmission pulse widths, and there are two corresponding data holding circuits, but there are n types of transmission pulse widths, and there are corresponding data holding circuits. It is also possible to adopt a configuration as shown in FIG. 2 in which n pieces are provided.

In FIG. 2, since n data holding circuits 2 are provided corresponding to the transmission pulse width, the noise average value whose data is held on the transmission pulse width side is selected by the data changeover switch 3, and the dividing circuit 4 The noise level correction value can be calculated using Therefore, the same effect as in the first embodiment can be obtained for more transmission pulse widths.

〔Effect of the invention〕

As described above, according to the present invention, the noise level average value is held corresponding to the transmitted pulse width, and the noise level correction value is calculated using this, so that the transmitted pulse differs in the pulse compression radar. This has the effect of providing a noise level correction device that can always maintain a constant noise level even if the receiving system changes and the noise level fluctuates.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a noise level correction device according to an embodiment of the present invention, FIG. 2 is a block diagram of a noise level correction device showing another embodiment of the invention, and FIG. 3 is a conventional noise level correction device. FIG. 4 is a block diagram of a pulse compression radar using a noise level correction device according to an embodiment of the present invention. In the figure, 1 is a noise sample circuit, 2a to 2n are data holding circuits, 3 is a data changeover switch, 4 is a division circuit, 5 is a noise level reference value, 6 is a multiplication circuit, 7a,
7b is a distributed delay circuit, 8 is a noise level correction device, 9
a and 9b are received signal changeover switches. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A device that corrects the noise level of the received signal in a pulse compression radar with multiple transmission pulse widths, which includes a noise sample circuit that adds and averages noise in accordance with the noise sample timing, and a noise sample circuit. A data holding circuit holds the output for each transmission pulse width, a data changeover switch selects the held data according to the transmission pulse width, and the noise level is determined by dividing the selected data by the noise level reference value. A noise level correction device comprising: a division circuit that calculates a correction value; and a multiplication circuit that uses the correction value to correct a noise level. (2) The noise level correction device according to claim 1, wherein in a pulse compression radar having a plurality of pulse widths, the noise level is always kept constant regardless of the pulse width.