JPH0526841Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a high frequency detection level detection circuit, and in particular to a high frequency detection circuit that can easily switch between multiple detection levels without cutting off the high frequency signal. This invention relates to a level detection circuit.

[Conventional technology]

Conventionally, when detecting the detection level of a high frequency signal such as a microwave, it is required to perform detection by switching the detection level depending on the level of the detection level.
For example, FIG. 3 shows a conventional detection level detection circuit, in which a first directional coupler 1 detects a high frequency signal, a transducer 2 converts it into a coaxial system, and a second directional coupler 1 converts it into a coaxial system. The coupler 3 branches the signal into a through mode signal, which is lower by a certain degree of coupling, and is detected by a first detector 4 and a second detector 5, respectively. Then, the high-level and low-level outputs of the detectors 4 and 5 are switched by the changeover switch 6A, and the outputs are switched between the alarm signal suppression circuit 14 and the alarm signal detection circuit 13.
The configuration is such that the meter 7 detects the signal after passing through it.

[Problem that the invention attempts to solve]

The conventional detection circuit described above has a changeover switch 6A.
The detection level is switched by switching the switch, but the high frequency signal may be cut off for a moment when this switch is switched, and the alarm signal detection circuit 13 is activated at the moment this signal is cut off. An alarm signal suppression circuit 14 for preventing this is considered essential. In addition, the changeover switch 6A
Because a two-contact switching type is required, a relay switch is often used, which creates the problem of complicating the detection circuit itself, such as requiring a circuit to operate the relay. Ta.

The present invention aims to provide a high frequency detection level detection circuit with a simplified circuit.

[Means for solving problems]

The high frequency detection level detection circuit of the present invention branches the detected high frequency signal by a second directional coupler, connects the first detector to the high level route on the through mode side, and connects the branched low level route to the high level route. furthermore, the second detector side is directly connected to the high frequency detection level detection means, and the first detector side is connected to the high frequency detection level detection means via an open/close type switch, The configuration eliminates the need for an alarm signal suppression circuit or relay circuit and allows switching between high and low detection levels.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. The high frequency signal detected with a certain degree of coupling by the first directional coupler 1 is converted into a coaxial system by the transducer 2, and converted into a through mode by the second directional coupler 3 with a certain degree of coupling. The signals that are lower by that amount are input to the first detector 4 and the second detector 5, respectively, and detection outputs corresponding to the respective signals are detected. The route on the low detection output side connected to the second detector 5 is connected to the alarm signal detection circuit 13 and the meter 7.
It is connected directly to the computer so that it can be monitored at all times. On the other hand, the high-output route connected to the first detector 4 is connected to the alarm signal detection circuit 13 and the meter 7 via a single-contact open/close switch 6, so that the route can be opened and closed. ing.

Here, the alarm signal detection circuit 13 detects a state where no signal is inputted or a state where the signal is extremely weak and generates an alarm.

According to this configuration, during normal detection, the switch 6 is left open and the high frequency signal detected by the first directional coupler 1 is detected through the second detector 5. On the other hand, when the level of the detected high-frequency signal decreases by the degree of coupling of the second directional coupler 3, the switch 6 is closed to enable detection of the signal in the route of the first detector 4. It becomes possible to keep the value indicated by the fluctuation of the value constant.

That is, FIG. 2 shows the relationship between the first detector 4 and the second detector 5.
This is an equivalent circuit diagram showing the principle that the detection output on the higher side is always detected by OR connection. This indicates that the power supply voltage is detected as the output.

As a result, when the switch 6 is closed in FIG. The output from the first detector 4, which is the higher detection output, is detected.

For example, the coupling amount of the second directional coupler 3 is set to 10 dB.
For example, when the switch 6 is open, the sensitivity of the meter 7 to the signal on the second detector 5 side, that is, the full scale, is 500W, for example.
Then, if switch 6 is closed when the level of the detected signal is lowered by 10 dB, then
The full scale of the meter for the signal on the first detector 4 side (there is almost no signal on the second detector 5 side) is 50W
Therefore, although the deflection of the meter 7 itself changes, the indicated value remains constant.

Therefore, in this detection circuit, the alarm signal detection circuit 13 is always connected to the second detector 5, so the high frequency signal is not cut off when the switch 6 is operated, and the alarm signal suppression circuit as in the conventional alarm signal suppression circuit is not cut off. 14
becomes unnecessary. Further, since the switch 6 may have a simple open/close switch structure, there is no need to use a relay or the like, and a relay circuit is also not required. As a result, the detection circuit can be simplified while switching the detection level as in the prior art.

[Effect of idea]

As explained above, the present invention connects the first detector to the high-level route of the high-frequency signal branched by the second directional coupler, the second detector to the low-level route, and further connects the second detector to the high-level route of the high-frequency signal branched by the second directional coupler. Since the detector side is directly connected to the high frequency detection level detection means, and the first detector side is connected to the high frequency detection level detection means via an open/close type switch, a signal cut-off state when switching the switch is avoided. This eliminates the need for an alarm signal suppression circuit, and by simplifying the switch, eliminates the need for a relay circuit, which has the effect of realizing switching between high and low detection levels with a simple circuit configuration.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram showing the operating principle of FIG. 1, and FIG. 3 is a circuit diagram of an example of a conventional detection circuit. DESCRIPTION OF SYMBOLS 1...First directional coupler, 2...Transducer, 3...Second directional coupler, 4...First detector, 5...Second detector, 6...Switch, 6A...
...Changing switch, 7...Meter, 8, 9...Diode, 10...Resistor, 11, 12...DC power supply, 13...Alarm signal detection circuit, 14...Alarm signal suppression circuit.

Claims (1)

[Scope of utility model registration request] The high-frequency signal detected by the first directional coupler is branched by the second directional coupler, and the first detector is connected to the high-level route on the through mode side, while the first detector is connected to the branched low-level route. 2 detectors are connected, the second detector side is directly connected to the high frequency detection level detection means, and the first detector side is connected to the high frequency detection level detection means via an open/close type switch. High frequency detection level detection circuit.