JPH07198839A - Dme receiver - Google Patents

Abstract

PURPOSE:To normally detect a question signal stronger than a CW jamming wave even if the CW jamming wave of a low level is continued. CONSTITUTION:A receiver 6 has an IF amplifier 9, a detector 10, a decoder 11 and an ARRC 12. A CW detector 20 has an AGC circuit 24 for controlling the IF amplifier, a DC detector 21 for comparing a DC output voltage of the detector with first and second threshold values to output first and second detection signals, a comparator 22 for counting output pulse number of the decoder to decide whether it is a predetermined number or not, an AND circuit 23 for outputting an AND of the output of the comparator 22 and the first detection signal of the DC detector, and a switch circuit 25 for applying an output of the ARRC or the AGC circuit to the IF amplifier according to the output of the AND circuit 23. An alarm suppressing timer 40 generates an alarm suppression signal of two stages based on the output of the AND circuit and the second detection signal. A random pulse generator 30 mixes a random pulse with the output pulse of the decoder based on the output of the AND circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to DME (Distan).
The present invention relates to a receiving apparatus for a ground station of CE Measuring Equipment.

[0002]

2. Description of the Related Art Conventionally, in a ground station of a DME that provides distance information from its own station to a traveling aircraft or the like, an inquiry pulse of a predetermined frequency emitted from an onboard device of the DME mounted on the aircraft. After receiving and demodulating the signal, decoding (deciphering) this interrogation pulse signal, giving a predetermined system delay time to code it again, and as a response pulse signal to the aircraft via a predetermined transmission system. I am sending. In the on-board device mounted on an aircraft, the response pulse signal is received and demodulated, the elapsed time between the inquiry pulse signal and the response pulse signal is measured, and the distance information from the ground station of the DME to its own device is obtained. It has gained.

This DME ground station is about 1000 pps (Pulse pairs Pes) even when there is no interrogation pulse signal from the on-board equipment mounted on the aircraft.
A random pulse signal of rSecond) is transmitted, and only when the interrogation pulse signal is received, a response pulse signal is transmitted instead of the random pulse signal.
Therefore, in a normal operation state, the DME ground station constantly transmits a pulse signal of 1000 to 2700 pps including the random pulse signal and the response pulse signal.

FIG. 4 is a diagram showing a basic configuration of the above-mentioned conventional DME ground station. The interrogation pulse signal from the onboard device is captured by the antenna 1 and sent to the receiving device 4 via the directional coupler 2 and the duplexer 3. The receiving device 4 is composed of a heterodyne circuit 5 and a receiver 6. The heterodyne circuit 5 mixes the interrogation pulse signal of 1 GHz band DME and the same 1 GHz band local signal from the transmitter 7 via a medium such as a diode mixer, and outputs a signal with a preset frequency difference between both signals. There is 63
Receiver 6 after converting to MHz IF signal (intermediate frequency signal)
Send to.

The interrogation pulse signal amplified, detected and decoded by the receiver 6 is re-coded by the transmitter 7 and emitted as a response pulse signal from the antenna 1 toward the aircraft via the duplexer 3 and the directional coupler 2. .

The monitor 8, which is one of the basic components, is a DM
An interrogation pulse signal of a predetermined level similar to the signal from the on-board device of E is input to the receiving device 4 via the directional coupler 2, decoded by the receiver 6 and then recoded by the transmitter 7, and a response pulse signal is received. As a result, the signal output from the transmitter 7 is received via the directional coupler 2, and the operating state of the ground station of the DME is constantly monitored. The monitor 8 performs an operation such as outputting an alarm signal and stopping the operation of the transmitter if any of the monitor items becomes abnormal, for example, the number of transmission pulses or the reception sensitivity.

FIG. 5 is a block diagram showing a conventional receiver 6 in a receiving device forming the basis of the ground station of the DME shown in FIG. 4, the interrogation pulse signal from the on-board device is captured by the antenna 1 of the ground station of the DME, the signal is converted by the heterodyne circuit 5 into an IF signal of 63 MHz band, and the IF of the receiver 4 shown in FIG. It is supplied to the amplifier 9. The IF amplifier 9 amplifies the supplied IF signal to a predetermined level and supplies the IF signal to the detector 10. Detector 10
Detects the supplied IF signal and supplies it to the decoder 11 as a video signal. The decoder 11 supplies the supplied video signal, that is, the interrogation signal (pair pulse signal having a predetermined interval) from the onboard device and the heterodyne circuit 5 of the receiving device 4.
A signal appearing at a predetermined time interval is decoded and output from the combined signal with the thermal noise signal generated and amplified inside. The decoder 11 of this type has a simple configuration that ANDs a signal that passes through a delay line having a predetermined time delay amount and a signal that does not pass through it, and a DME in which a system signal is formed by a pair pulse. It is an effective means for decoding signals in the system.

Therefore, the signal output from the decoder 11 is a single pulse signal which becomes a response signal by decoding the interrogation pulse signal from the on-board device, and a noise pulse which is accidentally generated at a predetermined interval from the thermal noise signal. It consists of random pulses obtained by decoding. In addition, the decoder 11 is provided with a function of generating a blanking gate pulse that suppresses the decoding function for a predetermined time (about 60 usec) each time the signal is decoded so that the decoded pulse train does not affect the transmission capability of the transmitter. There is.
ARRC (Automatic Repetition)
Rate Control) 12 outputs the number of output pulses of the decoder 11 from the predetermined value, that is, 1000 to 270.
In order to keep it within 0 pps, the number of output pulses of the decoder 11 is counted, and a DC signal for controlling the gain of the IF amplifier 9 is output according to the counted value.

The ARRC 12 is a kind of pulse / DC conversion circuit composed of an integrating circuit, a low-pass filter and a DC amplifier, which converts the number of pulses into DC and outputs a difference from a settable reference value to a decoder. A so-called known AGC (Automatic) that controls the number of pulses to a predetermined value
It has the same function as a Gain Control circuit.

[0010]

SUMMARY OF THE INVENTION This conventional receiver 6
Is an IF having a linear amplification characteristic suitable for a high gain amplifier capable of amplifying a low level (-95 dbm) interrogation pulse signal and a thermal noise generated by a heterodyne circuit to a level of several volts which can be detected by a decoder, and being capable of gain control.
I am using an amplifier. Therefore, unlike the logarithmic amplifier, the dynamic range is essentially narrow, and in this example, about -90.
Saturates at an input level of dbm.

Therefore, when a CW (continuous wave) of -90 dBm or more enters the receiver 6, the IF amplifier 9 cannot amplify the interrogation signal and also cannot output the thermal noise for random pulse generation to the decoder. Determines that the number of decoding pulses is insufficient and further works to increase the gain of the IF amplifier 9, resulting in no output pulse train from the decoder. Therefore, it becomes impossible to send the response pulse signal to the onboard equipment of the aircraft, which seriously affects the system operation of the DME, and the monitor of the ground station of the DME outputs the transmission pulse number alarm and the reception sensitivity alarm. If the above alarm continues for a predetermined time, there is a problem that the operation of the device is stopped.

On the other hand, the receiving sensitivity imposed on the ground station in the DME system is usually -95 dbm. This reception sensitivity is defined by the interrogation pulse signal level when the ratio of the number of response pulses to the number of interrogation pulses is 70%. 6d even if the reception sensitivity drops for some reason
b It is a system that can guarantee the coverage of DME up to -89dbm. Therefore, the reception sensitivity detection threshold value of the monitor is set to -89 dbm.

That is, it means that the gain of the receiver may be lowered to a level at which the receiving sensitivity of -89 dbm can be guaranteed. However, as described above, the conventional receiver 6 has a fundamental problem that it is saturated even with a weak level (−90 dbm) of CW interference.

A transponder device which solves this kind of problem is proposed in Japanese Laid-Open Patent Publication No. 62-249087. FIG. 6 shows a block diagram of this transponder device. According to this transponder device, the IF signal is
The amplifier 9 and the logarithmic amplifier 13 and the antilogarithmic amplifier 14 are supplied to the IF amplifier 9 as in the conventional receiver 6 described above.
It operates by the output signal of. If the CW signal is detected by the logarithmic amplifier 13, the analog switch 115 gives priority to the video signal from the antilogarithmic amplifier 14 to the video signal from the IF amplifier 9 and supplies it to the decoding circuit 16, thereby superimposing it on the CW signal. It is possible to detect the interrogation signal. The output of the decoder circuit 16 is given to the IF amplifier 9 via the AGC circuit 17.

However, this transponder device is effective when the CW signal is superimposed only while the interrogation signal is present, but it is possible to detect the interrogation signal when the CW signal is an interfering wave. However, since the output of the IF amplifier 9 is not supplied to the decoder circuit 16 as described above, even if the output is intentionally supplied, the IF amplifier 9 is still CW.
The signal is saturated. Therefore, since the output from the IF amplifier 9 is only DC, it becomes impossible to generate the random pulse required for the DME system, and it is difficult to solve the problem of operation stop like the above-mentioned conventional receiver. is there.

Here, the CW interference wave will be described. It is clear that there is no disturbance that aims to render a normal DME ground station inoperable, and conversely it is inherently difficult to protect if deliberate. Therefore, it is considered that the object of consideration is limited to those that approach the DME ground station and may radiate radio waves without noticing a bad spurious characteristic, such as general wireless communication devices such as mobile wireless devices.

The strength R _x (dbm) of the signal radiated from these radios and received by the ground station of the DME can be expressed by the following formula 1 regardless of the strictness.

[0018]

[Equation 1]

The antenna gain of the DME ground station is set to a realistic 8
and the transmission output of the wireless device is 10 W (+40 db
m), the 1 GHz band spurious characteristic of the radio device is -60d.
b. If the distance between the radio and the DME ground station is 0.1 NM, the CW interference level from the radio received by the DME ground station is about -90 dbm, which is practical and easy to occur frequently. is there.

An object of the present invention is to normally detect and respond to an interrogation signal stronger than a CW interference wave, even if a low level CW interference wave that is operationally acceptable in the operation of a DME ground station continues. Even if there is an unacceptable intensity of interference, if the disturbance is within the specified time, the operation will not be stopped. D
It is to provide an ME receiver.

[0021]

The present invention is directed to a receiver for receiving an IF signal, a CW detector connected to the receiver for detecting a CW interference wave from the IF signal, and connected to the CW detector. An alarm suppression timer for giving an alarm suppression signal to a monitor for monitoring the receiver, the receiver including an IF amplifier for receiving and amplifying the IF signal and a DC output signal of the IF amplifier. A detector that converts the voltage into a voltage, a decoder that decodes the output signal from this detector at predetermined time intervals, the number of output pulses of the output signal of this decoder, and the gain of the IF amplifier according to this count value. Outputs a control signal to control A
RRC and the CW detector is a DC of the detector.
AGC that outputs a control signal that maintains the output voltage at a predetermined value
A circuit, a DC detection circuit for comparing the DC output voltage of the detector with first and second threshold values and outputting first and second detection signals, and counting the output pulses of the decoder to a predetermined value. A pulse number comparator that determines whether the number is a number, an AND circuit that outputs a logical product of the first detection signal of the DC detection circuit and the detection signal of the pulse number comparator,
A switch circuit for selecting either the output signal of the ARRC or the output signal of the AGC circuit by the output signal of the AND circuit and adding it to the IF amplifier of the receiver, wherein the alarm suppression timer is the DC detection circuit. Of the second detection signal, a selection circuit for receiving the output signals of the AND circuit and the timer, and an OR circuit for receiving the output signals of the timer and the selection circuit and outputting the alarm suppression signal. Characterize.

The present invention also includes a receiver for receiving an IF signal, a CW detector connected to the receiver for detecting a CW interference wave from the IF signal, and the receiver connected to the CW detector for An alarm suppression timer for giving an alarm suppression signal to the monitor to be monitored, and a random pulse generator connected to the output side of the receiver, the receiver receiving the IF signal and amplifying it. IF amplifier, a detector that converts the output signal of this IF amplifier into a DC voltage, a decoder that decodes the output signal from this detector at predetermined time intervals, and the number of output pulses of the output signal of this decoder is counted. AR for outputting a control signal for controlling the gain of the IF amplifier according to the lever count value
RC, the CW detector outputs an AGC circuit which outputs a control signal for maintaining the DC output voltage of the detector at a predetermined value, and the DC output voltage of the detector having first and second thresholds. A DC detection circuit that outputs a first and a second detection signal by comparing the value with a value; a pulse number comparator that counts the output pulses of the decoder to determine whether the number is a predetermined number; AND circuit for outputting a logical product of the detection signal of the pulse number comparator and the detection signal of the pulse number comparator, and the output signal of the AND circuit selects either the output signal of the ARRC or the output signal of the AGC circuit to select the receiver. And a switch circuit for adding to the IF amplifier, the alarm suppression timer receives a second detection signal of the DC detection circuit, and an output signal of the AND circuit and the timer. A selection circuit, wherein in response to an output signal of the timer and the selection circuit includes an OR circuit for outputting the alarm suppression signal, the random pulse generator,
A pulse generating circuit connected to an output terminal of the decoder for generating a predetermined number of random pulses; a gate circuit for controlling passage of the random pulse by an output signal of the AND circuit; and an output pulse of the decoder and the gate circuit. And an OR circuit for ORing and outputting the passed random pulse.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In this embodiment, the same components as those in FIG. 5 are designated by the same reference numerals. In this embodiment, the conventional receiver 6 is provided with a CW detector 20 and a random pulse generator 3.
0 and an alarm suppression timer 40 are provided.

In a normal condition where there is no CW interference,
Similar to the conventional DEM receiver, only the operation of the receiver 6 amplifies the interrogation pulse signal and the thermal noise generated in the preceding heterodyne circuit by the IF amplifier 9, and the decoder 11 decodes the interrogation pulse signal and the thermal noise. Is generating a random pulse. 2A to 2C show examples of operation waveforms of the receiver 6 when there is no CW interference wave. That is,
In this state, since the CW signal does not exist, A of the receiver 6
The gain control signal supplied from the RRC 12 to the IF amplifier 9 is supplied through the switch circuit 25 of the CW detector 20. The decoder output pulse of the receiver 6 is output to the transmitter through the OR circuit 33 of the random pulse generator 30. The output of the OR circuit 33 has the random pulse generator 3
The lantam pulse generated by the pulse generation circuit 31 is not output because it is prohibited by the gate circuit 32. Further, the alarm suppression timer 40 does not output the alarm suppression signal.

If a CW interference wave stronger than a predetermined value is input to the receiving device 6, a DC voltage corresponding to the CW interference wave intensity appears in the detector 10 of the receiver 6. This DC voltage is supplied to the DC detection circuit 21 and the AGC circuit 24 of the CW detector 20. In this embodiment, the DC detection circuit 21
Detects the DC voltage with two threshold values set individually, supplies one of the first detection signals to the AND circuit 23, and the second detection signal is the alarm suppression timer. Supply to 40.

The threshold value of the first detection signal supplied to the AND circuit 23 is a weak level (-90 dbm in this embodiment) CW interference wave that can secure normal reception sensitivity. The threshold value of the second detection signal supplied to the alarm suppression timer 40 is a strong level (in this example, a value) that lowers the gain of the IF amplifier 9 to the lower limit value of the reception sensitivity that is acceptable to the ground station in the operation of the DME system. -85 dbm) CW
It is a disturbing wave. This second threshold value makes it difficult to generate random pulses due to thermal noise even if the 6 dB gain is lowered from the point where the IF amplifier 9 begins to saturate, but the interrogation pulse from the on-board device within the coverage of the DME system. It is a value that can sufficiently decode the signal. The threshold values of the first and second detection signals can be set according to the characteristics of the receiver.

On the other hand, the AGC circuit 24 receives the input DC
The voltage is amplified to a level at which the IF amplifier 9 can be controlled so as not to saturate and output to the switch circuit 25. CW detector 2
The pulse number comparator 22 of 0 constantly counts the decoded pulses from the receiver 6 and outputs a detection signal to the AND circuit 23 when the number becomes equal to or less than a predetermined value, that is, 1000 pps. AN
The D circuit 23 supplies an AND output signal to the switch circuit 25 when both of the two detection signals appear, and AR
The gain control signal from the RC 14 is switched to the gain control signal from the AGC circuit 24 and supplied to the IF amplifier 9.

The AND output signal of the AND circuit 23 is
It is also supplied to the gate circuit 32 of the random pulse generator 30 and the timer 41 of the alarm suppression timer 40. The CW detection is performed by ANDing the output signals of the DC detection circuit 21 and the pulse number comparator 22 described above. The reason is that the inquiry signal is normally output while the decode pulse is present even if there is an influence of the CW interference wave. This is to switch the random pulse to the signal from the random pulse generator 30 when the number of decoded pulses including the random pulse is reduced to a predetermined value or less by detecting with the reception sensitivity of.

When the IF amplifier 9 is controlled by the signal from the AGC circuit 24, the video signal level output from the detector 10 decreases as the input CW signal level increases, and finally the thermal noise signal. Hardly appears, and the decoder 11 detects only a strong interrogation signal from an onboard device that is traveling near the ground station of the DME. In this case, as described above, the CW detection signal from the AND circuit 23 drives the switch circuit 32 of the random pulse generator 30 to generate a predetermined number (1000).
pulse (more than pps) is passed to the OR circuit 33, ORed with the decoded pulse from the decoder 13 and supplied to the transmitter to reduce the number of transmitted pulses, which is one of the above-mentioned two problems in the CW interference wave input. Solve. An example of the operation waveform of the receiver 6 in the CW interference wave input is shown in d to j of FIG.

From the decoder 11 to the pulse generation circuit 31
As described above, the signal supplied to is a blanking gate signal that is the same as the signal that suppresses the decoder 11 from continuously decoding at a timing shorter than a predetermined interval (about 60 us). Therefore, the decoded pulse from the decoder 11 is output to the transmitter with priority over the random pulse from the pulse generator 31. Two C's from the CW detector 20 described above
The alarm suppression timer 40 supplied with the W detection signal,
The monitor alarm suppression signal is output while the output from the AND circuit 23, that is, the weak CW interference wave is present. Therefore, it is guaranteed that the DME ground station can continue to operate with respect to the CW interfering waves up to the reception sensitivity reduction that is acceptable to the DME ground station.

On the other hand, in the case of a strong level CW interfering wave, in the present embodiment, a CW detection signal of -84 dbm, an allowable alarm suppression signal for several seconds as shown in the waveform charts k to r in FIG. It is generated, ORed with the alarm suppression signal in the weak CW interference wave, and output. Therefore, when the CW interference wave is received at a level of -84 dbm or more, the alarm suppression signal from the alarm suppression timer 40 is generated for only a few seconds, and if it continues for a longer time, the monitor alarm can no longer be suppressed.

The monitor sends an interrogation signal of a predetermined level to the receiving device, counts response signals in response to the inquiry signal, and constantly monitors the reception sensitivity for several seconds (4 to 10).
If the abnormality continues, an alarm signal to stop the device will be output. Therefore, the output signal of the alarm suppression timer 40 suppresses the alarm due to the decrease in reception sensitivity, which is another problem when there is a CW interference wave that lasts for a predetermined time, according to the CW interference wave intensity, and DME The operation of the ground station of the DME is maintained, and the deterioration of the service to the airborne device due to the stop of the operation of the ground station of the DME is improved. Normally, when the DME ground station stops operating due to a monitor alarm, the cause is investigated to ensure the safety of aircraft navigation, and after the countermeasures are taken, the stop is continued until it is determined to be operable.

[0034]

Industrial Applicability The present invention is conventionally difficult because it is possible to normally detect and respond to an interrogation signal stronger than the CW interfering wave even if a low level CW interfering wave that is operationally allowable in the operation of the ground station of the DME continues. It is possible to continue the distance measurement service to the onboard equipment. Further, the present invention can solve the problem that the operation is stopped even if there is an interference wave of an unacceptable intensity for operation, as long as the interference is within a predetermined time. Further, according to the present invention, it is possible to reduce the dispatch of maintenance personnel and the work of investigating the cause of the stoppage due to the operation stoppage which was originally unnecessary.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an operation waveform diagram of the receiving apparatus according to the embodiment of the present invention.

FIG. 3 is an operation waveform diagram of an alarm suppression timer of the receiving device according to the embodiment of the present invention.

FIG. 4 is a block diagram showing a basic configuration of a conventional DME receiving device.

5 is a block diagram showing a receiver in the DME receiving device of FIG. 4. FIG.

FIG. 6 is a block diagram showing another example of a conventional DME receiving device.

[Explanation of symbols]

 1 Antenna 2 Directional Coupler 3 Duplexer 4 Receiver 5 Heterodyne Circuit 6 Receiver 7 Transmitter 8 Monitor 9 IF Amplifier 10 Detector 11 Decoder 12 ARRC 20 CW Detector 21 DC Detection Circuit 22 Pulse Number Comparator 23 AND Circuit 24 AGC Circuit 25 Switch Circuit 30 Random Pulse Generator 31 Pulse Generation Circuit 32 Gate Circuit 33 OR Circuit 40 Alarm Suppression Timer 41 Timer 42 OR Circuit 43 Selection Circuit

Claims (2)

[Claims] 1. A receiver for receiving an IF signal, and a C connected to the receiver for detecting a CW interference wave from the IF signal.
The receiver comprises a W detector and an alarm suppression timer connected to the CW detector to provide an alarm suppression signal to a monitor for monitoring the receiver, the receiver receiving and amplifying the IF signal. An IF amplifier and a detector for converting an output signal of the IF amplifier into a DC voltage,
A decoder for decoding the output signal from the detector at predetermined time intervals, and an ARRC for counting the number of output pulses of the output signal of the decoder and outputting a control signal for controlling the gain of the IF amplifier according to the count value. And C
The W detector includes an AGC circuit that outputs a control signal that maintains the DC output voltage of the detector at a predetermined value, and a D detector of the detector.
A DC detection circuit that outputs the first and second detection signals by comparing the C output voltage with the first and second threshold values, and counts the output pulses of the decoder to determine whether or not it is a predetermined number. A pulse number comparator, an AND circuit for outputting a logical product of the first detection signal of the DC detection circuit and the detection signal of the pulse number comparator, and an output signal of the AND circuit, or an output signal of the ARRC or the AGC circuit. A switch circuit for selecting one of the output signals of the above and adding it to the IF amplifier of the receiver, the alarm suppression timer includes a timer for receiving the second detection signal of the DC detection circuit, the AND circuit and the timer. And an OR circuit that receives the output signals of the timer and the selection circuit and outputs the alarm suppression signal. DME receiving device. 2. A receiver for receiving an IF signal, and a C connected to the receiver for detecting a CW interference wave from the IF signal.
A W detector, an alarm suppression timer connected to the CW detector for giving an alarm suppression signal to a monitor for monitoring the receiver, and a random pulse generator connected to the output side of the receiver. The receiver comprises an IF amplifier for receiving and amplifying the IF signal, a detector for converting an output signal of the IF amplifier into a DC voltage, and an output signal from the detector for decoding at a predetermined time interval. And a ARRC that counts the number of output pulses of the output signal of the decoder and outputs a control signal that controls the gain of the IF amplifier according to the count value. The CW detector includes: An AGC circuit that outputs a control signal that maintains the DC output voltage of the detector at a predetermined value, and a DC output voltage of the detector that compares the DC output voltage with first and second threshold values. A DC detection circuit that outputs a detection signal, a pulse number comparator that counts the output pulses of the decoder and determines whether or not a predetermined number, and a first detection signal of the DC detection circuit and the pulse number comparator An AND circuit that outputs a logical product of signals, and an output signal of the ARRC or an AG of the output signal of the AND circuit.
Select one of the output signals of the C circuit to select the IF of the receiver.
A switch circuit added to an amplifier, wherein the alarm suppression timer has a timer for receiving a second detection signal of the DC detection circuit, a selection circuit for receiving output signals of the AND circuit and the timer, the timer and the selection circuit. And an OR circuit that outputs the alarm suppression signal upon receipt of the output signal from the random pulse generator, wherein the random pulse generator is connected to an output terminal of the decoder to generate a predetermined number of random pulses, and the random pulse generator. Pulse the AN
A DME receiving device comprising: a gate circuit for controlling passage by an output signal of the D circuit; and an OR circuit for ORing and outputting an output pulse of the decoder and a random pulse passing through the gate circuit.