JPH0718922B2 - Transponder device - Google Patents

Description

The present invention relates to a DME device (distance measuring device) which is a short-range navigation assistance system, or a transponder device in a tacan device, more specifically, a CW (continuous wave) of a receiver. ) Regarding oppression.

(Prior Art) A DME device and a tanker device, which are composed of an interrogator (onboard device) and a transponder device (ground device), are used as a short-distance navigation assistance system. These systems are configured such that an interrogator issues an interrogation pulse, and a transponder device receiving the interrogation pulse transmits a response pulse after a prescribed delay time (50 μs). Therefore, the interrogator can measure the distance to the transponder device by knowing the time from when the interrogation pulse is emitted until the response pulse is received.

The interrogator emits an interrogation signal called a Gaussian pulse, which has a narrow pulse spectrum and has a pulse width of 3.5 μs and a pulse interval of 12 μs.
Normally, the CW leakage of this interrogation pulse is very small and is below the noise level in the transponder device, so that it does not adversely affect (stop operation) the transponder device. However, there may be an interrogator with a large CW leakage, and if the transponder device that receives the interrogation signal increases the decoding rate in the receiver and overloads the transmitter that transmits the number of decoded pulses, It may be tightened. Therefore, the transponder device in this state is brought into operation stop by the monitoring circuit in the transponder device in order to protect the transmitter.

FIG. 3 is a block diagram of a conventional transponder device in consideration of CW suppression.

The interrogation signal emitted by the transmitter 11 of the interrogator 10 is received by the antenna 21 of the transponder device 20.
The interrogation signal input to the hollow wire 21 is mixed with the local signal from the local signal generator 26 in the mixer preamplifier 25 via the duplexer 22 and the preselector 24, and is converted into an IF signal. The IF signal is sent to a logarithmic amplifier 27 and a variable attenuator 28 which operates in proportion to the output of the logarithmic amplifier 27. The IF signal passed through the variable attenuator 28 is sent to a decoding circuit 30 which is amplified and detected by the IF amplifier 29 and decodes the interrogation pulse generated from the interrogation pulse and receiver noise. A part of the output of the decoding circuit 30 is sent to the AGC circuit 31, and the gain of the IF amplifier 29 is controlled so that the decoding number of the decoding circuit 30 becomes constant.
The gain margin of the IF amplifier 29 is about 10 dB for circuit stability. Therefore, when the transponder device 20 receives the interrogation signal having a CW leakage that is tens of dB stronger than the lowest triggering level, the DC output of the logarithmic amplifier 27 operates the variable attenuator 28 to bring it to the input CW level. Since the compared attenuation amount is inserted, the input to the IF amplifier 29 is a minute CW.
The interrogation signal becomes a signal, and the interrogation signal superimposed on the CW signal also becomes very small, making it difficult to detect the interrogation signal. Further, the ratio between the interrogation signal and the CW component does not change because it is simply attenuated.

(Problems to be Solved by the Invention) In a conventional transponder device, when a CW signal higher than the minimum triggering level of the receiver by several tens of dB is applied, the output of the variable attenuator is logarithmically small as described above. Becomes a value,
In the receiver, the ratio with the interrogation signal superimposed on the CW component is not improved. Therefore, the interrogation signal larger than the CW component by several dB cannot be detected, and since the variable attenuator is always inserted, the reception sensitivity is lowered.

An object of the present invention is to provide a transponder device capable of surely detecting an interrogation pulse even when a CW signal larger than the minimum triggering level of the receiver by several tens of dB is applied.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the transponder device according to the present invention is a transponder device in a DME device or a tacan device, a hollow wire, and a transmitter that sends a response pulse to an inquiry pulse, A preselector, a received wave of the antenna is connected to the preselector, and a duplexer and a local signal generator that connect a response pulse of the transmitter to the antenna are mixed, and the preselector output and the local signal generator are mixed. A mixer preamplifier that produces an IF signal by an IF amplifier that amplifies the mixer preamplifier output,
A logarithmic amplifier for logarithmically amplifying the mixer preamplifier output, an antilogarithmic amplifier for amplifying the mixer preamplifier output according to the logarithmic amplifier output, and the IF amplifier output and the antilogarithmic logarithm according to the logarithmic amplifier output. An analog switch for switching the connection of the amplifier output, a decoding circuit for decoding the paired pulse of the analog switch output, a gain of the IF amplifier so that the decoding circuit output is detected and the decoding number of the decoding circuit becomes constant. It is composed of an AGC circuit for controlling the.

(Example) Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a transponder device according to the present invention. In this figure, the variable attenuator is removed from the conventional example, and an antilogarithmic amplifier 40 and an analog switch 41 are provided. Other components are the same as those in the conventional example.

Normally, the leakage of CW superimposed on the interrogation signal emitted from the interrogator is very small. Therefore, logarithmic amplifier 27
Control the analog switch so that the output of the IF amplifier 29 is connected to the decoding circuit 30.

As a result, the output of the IF amplifier 29 is decoded. Next, when an interrogator signal with a large CW leakage is received, the output waveform of the mixer preamplifier 25 becomes a signal with a large CW component as shown in FIG. 2a as compared with the interrogator signal. This signal is input to the IF amplifier 29, the antilogarithmic amplifier 40, and the logarithmic amplifier 27, respectively. However, the logarithmic amplifier 27 output controls the analog switch 41 so that the antilogarithmic amplifier 40 output is connected to the decoding circuit 30. Therefore, in this case, the output of the antilogarithmic amplifier 40 is selected instead of the output of the IF amplifier 29.

The antilogarithmic amplifier 40 is connected to the second logarithmic amplifier 27 by the DC output of the logarithmic amplifier 27.
It outputs a signal as shown in FIG. As a result, the part of the interrogation signal is particularly amplified, so that the interrogation signal superimposed on the CW signal can be easily detected.

FIG. 3 is a diagram comparing the input / output characteristics of the device according to the present invention with those of the conventional device.

e is the characteristic according to the present invention, and d is the characteristic of the conventional device. In the conventional characteristic, the ratio of the input at the triggering level to the CW input is the characteristic of d at the output, and thus the ratio of the CW output is increasing.

On the other hand, according to the present invention, the ratio of the input at the triggering level to the CW input is significantly reduced at the output. In the case of FIG. 2c, the CW suppression improvement amount is A.

(Effects of the Invention) As described above in detail, the present invention uses the analog switch to output the IF logarithmic amplifier output when the leakage of CW superimposed on the interrogation signal is small and the leakage of CW is large. Since it is configured to be selectively connected, it has an effect of suppressing the CW interference of the interrogation pulse and an effect of preventing the deterioration of the reception sensitivity even when the leakage of the CW signal is large.

[Brief description of drawings]

1 is a block diagram showing an embodiment of a transponder device according to the present invention, FIG. 2 is a diagram showing the inverse logarithmic amplifier characteristic and CW / signal ratio characteristic in FIG. 1, and FIG. 3 is a conventional transponder device. It is a block diagram. 10 …… interrogator 11 …… transmitter 12 …… receiver 13 …… antenna 20 …… transponder device 21 …… antenna 22 …… deplexer 23 …… transmitter 24 …… preselector 25 …… mixer preamplifier 26… … Local signal generator 27 …… Logarithmic amplifier 28 …… Variable attenuator 29 …… IF amplifier 30 …… Decoding circuit 31 …… AGC circuit 40 …… Inverse logarithmic amplifier 41 …… Analog switch

Claims (1)

[Claims] 1. A transponder device in a DME device or a tacan device, wherein an antenna, a transmitter for transmitting a response pulse to an inquiry pulse, a preselector, and a received wave of the antenna are connected to the preselector, and the transmission is performed. A duplexer and a local signal generator that connect the response pulse of the machine to the antenna, a mixer preamplifier that mixes the preselector output and the local signal generator to produce an IF signal, and amplifies the mixer preamplifier output IF amplifier, a logarithmic amplifier for logarithmically amplifying the mixer preamplifier output, an inverse logarithmic amplifier for amplifying the mixer preamplifier output according to the logarithmic amplifier output, and an IF amplifier according to the logarithmic amplifier output An analog switch for switching the connection between the output and the inverse logarithmic amplifier output, and a pair pulse for the analog switch output. A decoding circuit for reading, AG decoding speed of the decoding circuit detects the decode circuit output controls the gain of the IF amplifier to be constant
A transponder device comprising a C circuit.