JPS5956180A - Radar device - Google Patents

Abstract

PURPOSE:To obtain an optimum heater voltage corresponding to a pulse width, by detecting an electric power accumulated in a charging circuit which uses a magnetron as a load, and generating and supplying a heater voltage on the basis of the accumulated power. CONSTITUTION:An AC signal boosted by a transformer 1 is rectified and smoothed by diodes 2 and 3, a smoothing coil, and a capacitor 5. Charges in the capacitor 5 are transferred to a capacitor 9. The charges accumulated in the capacitor 9 are discharged through a thyristor 10 and the primary coil L1 of a transformer 11. The magnetron 12 is excited by the discharging. The amount of charge flowing through the capacitor 9 is detected by a smoothing circuit 14 and supplied to a control signal generating circuit 15. Then, a heater voltage generating circuit 16 outputs the heater voltage of the magnetron 12 on the basis of the output of the control signal generating circuit 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pulse modulation circuit that generates detection radio wave pulses in a radar device.

The magnetron used for wave pulse generation is usually rated 6
, 3V is applied, but when the magnetron is driven, a voltage lower than the above is sufficient due to the self-heating effect and is preferable from the viewpoint of longevity. In addition, the application below the above-mentioned rated value is affected by the pulse width of the generated radio wave pulse, and the longer the pulse width, the lower the heater voltage can be. By the way, radar equipment generally uses S of the detection signal.
In order to improve the /N ratio, a suitable pulse width of the radio wave pulse is set for each specific detection range group having a constant repetition frequency or individually. Therefore, a means is required to switch the voltage applied to the heater to a suitable value each time the pulse width is changed, and in this respect, in the conventional system W, several voltage generating circuits each having a preset voltage value are energized.

However, it is necessary to switch and send out a predetermined heater voltage according to the detection range group and the switchable pulse width. However, the method that allows this requires a large number of voltage generating circuits, which leads to the complexity of the circuit.

The present invention has been made in view of the above, and provides a device that detects electric power accumulated in a charging circuit with a magnetron as a load, and generates and supplies an appropriate heater voltage based on this accumulated electric power. It is something.

The following description will be made based on the embodiments shown in the drawings.

In FIG. 1, reference numeral 1 denotes a transformer that boosts an AC signal from a power source to a predetermined value, and the boosted AC signal is rectified and smoothed by a diode 2.3, a smoothing coil 4, and a capacitor 5. Therefore, a DC voltage of a predetermined value appears at point A. The charge in the capacitor 5 is charged to the capacitor 9 via a coil 6 having a large inductance, a diode 7 for preventing backflow, and a coil 8. At this time, the voltage drop at point A due to the discharge of capacitor 5 is supplied from the coil 4 side, and as a result, the potential at point A is kept constant. Although not shown in the figure, the coil 8 and the capacitor 9 are made up of a plurality of elements and are switched and connected to obtain the same number of oscillation cycles as the pulse width switching stage.

The discharge is caused by the electric charge accumulated in the capacitor 9 flowing through the primary coil L1 forming the transformer 11 via the thyristor 10 by sending a transmission trigger pulse (FIG. 2a) to the gate of the thyristor 1o. . The discharge time, ie, during the transmission pulse, is determined by the oscillation period based on the coil 8 and capacitor 9. This rapid discharge causes the secondary and tertiary coils Ij2 and l-18 of the transformer 11 to
is set to a high potential and excites the magnetron 12 during that time.

Then, the capacitor 9 is subsequently charged. The above charging is performed at an oscillation period based on the coil 6 and capacitor 9 (FIG. 2b). Note that the charging period (1/4 of the oscillation period) based on the oscillation period is set slightly smaller than the transmission repetition period in order to compensate for charging (see the charging current waveform in FIG. 2C).

Now, the amount of charge flowing into the capacitor 9 in this way is equal to the amount of charge flowing into the capacitor 5 from the coil 4 side, as described above. This current flows from the coil 4 through the capacitor 5 to the resistor 13 at a substantially constant level, and the amount of current appears as pressure at point DK'. 14 smoothes the flowing current to point D K '3j1. This is a smoothing circuit that detects the average voltage of the above voltages.

Here, the amount of charge accumulated in the capacitor 9, that is, the average anode input power of the magnetron, ΣOV"f, is equal to the amount of charge flowing into the capacitor 5, but the average anode input power and the detected smoothed voltage are Therefore, for example, in Toshiba Magne) a 2J42,
The heater voltage during operation is expressed as (Toshiba Electron Tube Technical Data, Microwave Tube, p. 157, 1976, 9)
As stated above, heater voltage = 6.3 (1 - smoothed voltage Xk)... (1) However, k is expressed as a proportionality constant. 15 is a control signal generation circuit that calculates the above equation (1) and sends out a heater voltage or a signal corresponding thereto in digital or analog form; 16 is a control signal generation circuit that applies a predetermined heater voltage to the heater of the magnetron 12 based on the control signal; This is a heater voltage generation circuit. Although not shown, a switching means is provided to the heater voltage generating circuit 16 so that the rated voltage of 6.3 mm is applied when the magnetron is not in operation, and the predetermined heater voltage is applied only when the magnetron is in operation. be. This switching is performed based on, for example, a transmission trigger pulse input to the gate of the thyristor 10.

According to the present invention, the detection range group is related to the frequency f, and during the switchable pulse, it is related to the capacitance [0] of the capacitor 9. This causes the change to appear, and the change is automatically detected by the smoothing circuit 14 to generate a predetermined heater voltage.

Further, even when the detection range group and the types of pulses are passed through multiple stages (or the pulses are continuous), there is no need for any complicated circuits as in the prior art.

Note that the relationship between the average anode input power and the heater voltage is not limited to the relationship ls'=I shown in the example, but can be any relationship determined depending on the type of magnetron used. It is good to design the control signal generation circuit 15 based on this.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a waveform diagram thereof. Patent applicant Furuno Electric Co., Ltd.

Claims (1)

[Scope of Claims] A radar device that excites a magnetron using discharge in a pulse modulation circuit and sends out a predetermined radio wave pulse, comprising: a detection circuit that detects charging power to the pulse modulation circuit; and an output of the detection circuit. and an applied voltage supply circuit that controls and supplies voltage to a heater of a magnetron in such a manner that the applied voltage is decreased as the charging power increases based on the above.