JPS63208782A - Skitter pulse generator - Google Patents

Abstract

PURPOSE:To enable stable transmission by reading skitter pulse interval data which are stored together with added array characteristics corresponding to a relative distribution rate by using random code addresses, and generating skitter pulses. CONSTITUTION:A skitter pulse interval data memory 2 is stored with data on time intervals between skitter pulses together with added array characteristics corresponding to the relative distribution rate of pulse intervals with respect to a number preset according to the quantization step. This memory 2 is read out according to the output of a random code generator 1 as addresses and its read data are inputted to a counter 3. The counter 3 counts up every time interval is inputted and sends a count-down signal to a D-FF 5 through an inverter 4 at the end of the counting operation. the output of the FF5 is utilized as skitter pulses.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a Sukitsuta pulse generator, and in particular to a Sukitsuta pulse generator for stable emission of Sukita pulses emitted from a ground station as a transponder of a DME device toward an airborne station. Regarding the generator.

[Conventional technology]

DME equipment is well known, in which when it receives an interrogation pulse from a flying aircraft, it sends out a response pulse, and the aircraft learns the distance to its own ground station from the time from when it issues the interrogation pulse to when it receives the response pulse. ing.

At the ground station, even when there are no questions from the airborne station, approximately 100
c) PP/8 (Pulse Pa1rs P
Twin pulses are transmitted at random timing at a rate of er 5 econd). These twin pulses are a pair of 3.5 μSEC pulses separated by 12 μSEC from each other, and when an interrogation pulse arrives, it is replaced by a response pulse for the onboard station. This twin pulse train is called a squirrel pulse or a random pulse.

The airborne station that received this Sukitsuta pulse receives the A of its receiver.
GC (Automatic Ga1ri Control)
l) The function is always active, and communication with the ground station can be performed with a reception gain of M suitable for the distance to the ground station.

The squirrel pulse used for this purpose is generated by detecting and utilizing the thermal noise of a receiver at a ground station at a certain level.

FIG. 2 is a schematic diagram of a conventional squirter pulse generation circuit. In FIG. 2, the mixer 6 mixes the received signal input from the onboard station with a local oscillation signal and converts it into an intermediate frequency, but it generates thermal noise even when unmanned. This thermal noise is sent to a variable gain amplifier 7 and then supplied to a level detector 8. The level detector 8 selects and outputs only inputs having a predetermined level or higher and supplies them to the counter 9 .

In this way, the output of the level detector 8 provided to the counter 9 is determined by the magnitude of the thermal noise pulse generated by the mixer 6 that exceeds a certain level and the band limit by the variable gain amplifier 7 or the like. This is the random pulse received, Tapasu.

When the counter 9 receives such pulses, it counts them and supplies the counted number to the pulse number voltage converter 10.

The pulse number/voltage converter 10 converts the input random pulses into a voltage corresponding to the number of pulses, and supplies this to the comparator 11 .

The comparator 11 compares the output of the pulse number voltage converter 10 and the reference voltage, and outputs the difference between the two as a gain control voltage of the variable gain amplifier 7 to control its gain, thereby adjusting the number of squirting pulses as described above. I try to keep it to a number.

In this way, on the ground station side, AGC control is applied so that the number of tapers is almost constant at all times even if there are fluctuations in the received signal input level due to the distance difference between the ground station and the airborne station. We are trying to stabilize the situation.

[Problem that the invention seeks to solve]

However, the above-mentioned conventional techniques have this extreme disadvantage.

The tapulse generator has the following problems.

In other words, the interrogation pulse from the airborne station includes a so-called multi-pulse wave that passes through multiple paths in addition to the direct wave.
This has the disadvantage that not only the distance measurement performance but also the control voltage in the AGC control of the ground station, that is, the function of holding the squirrel pulse, differs from the actual situation.

In addition to the effects of such multipath waves, DME@
Even when there is a strong level CW flaw signal leaking from other devices co-located with the DME device or from the transmission monitor circuit of the DME device itself, a strong AGC voltage is applied to the variable gain amplifier 7 of the ground station. The disadvantage is that the gain is significantly reduced, and as a result, the thermal noise output, which is the source of the squitter pulses, is significantly suppressed, making it difficult to maintain the number of squitter pulses.

Furthermore, in recent years, in an effort to eliminate the effects of multipath in DME equipment, the ground station detects the low level range of the leading edge of the preceding pulse of the paired pulses of the interrogation signal received from the airborne station to improve ranging accuracy. MLS (Micro
ave Landing System), but when using such a method, the effects of multipath among the drawbacks mentioned above can be largely eliminated, but the effects of other co-located equipment and DME The disadvantage is that the influence of the strong CW flaw signal from the equipment is significantly amplified, the output of the 91% noise is greatly suppressed, and it is inevitable that the squirter pulses cannot be controlled.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a squitter pulse generator that can fundamentally eliminate the effects of multipath waves and CJfi signal leakage.

[Means for solving problems]

The present invention provides a short pulse generator that generates short pulses to be emitted from a ground station to an airborne station of a DME device, and includes short pulse interval data indicating a time interval between the short pulses and tap pulses. A squitter pulse interval data storage means for storing a number set in advance based on the quantization step and the number of addresses of the squitter pulse interval with array characteristics corresponding to the relative distribution rate of the squitter pulse intervals at a set address; Random code generating means that generates a random code with a correspondingly preset number of bits and uses the random code as an addressing signal to read out the spacing and pulse interval data stored in the squirting pulse data storage means; and a squitter pulse forming means for forming a squitter pulse based on the squitter pulse interval data read from the squitter pulse storage means.

q Example] Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. The embodiment shown in FIG. 1 includes a random code generator 1, a squitter pulse interval data memory 2, a counter circuit 3, an inverter 4, and a D-type flip-flop circuit 5.

The random code generator 1 generates PN (Pseud.

No1se, pseudo-noise) using a code generator, n
A random code with the longest code sequence of ÷2''-1 bit is generated by feeding back the logical combination of the shift registers of the stages to the input side.In this embodiment, the PN code is generated using the PN code generator as described above. Although it is generated as a random code, it is of course possible to use other composite code sequences such as gold codes instead.The number of bits of the random code generated in this way is determined by using this random code as an addressing signal. The random code generator 1 is determined according to the number of squitter pulse interval data to be used, which will be described later, and is set to 12 bits in this embodiment.This random code generator 1 is driven by a clock signal CLK, and this clock signal CLiK is It is also used as a drive signal for other component devices other than the controller 4.

I like to use 280M, tapulse interval data memory 2
The stored data is read out using the random code received from the random code generator 1 as an addressing signal.

Here, the answer and storage format of the data stored in the squitter pulse interval data memory 2 will be explained.

The squitter pulse interval data is stored corresponding to the distribution of the squitter pulse intervals.

FIG. 3 is a characteristic diagram of the spacing and taperus interval distribution of the DME device. The horizontal axis is the spacing interval expressed in μS (microseconds), and the time step is 54 μs. Further, the vertical axis indicates the relative distribution rate of the pulse interval of the squirting pulse. From a time point of view, it can be said that most of the transmission pulses emitted from the ground station are Sukitsuta pulses. Approximately 1000 of these squitter pulses are output even when there is no response signal, and on a scale of 100%, 50% is 60 to 270.
It is distributed in the μs region, and at least 42% are solid lines!
Distribution between, 3% is between real fi11s and dotted line 8 and solid line l!, respectively. Distribution is between 2 and dotted line, and 2 chi is dotted.
It has been found from a number of operational results that this is distributed in the areas above and below the - lines Ll and RI, respectively.

What this means is that, for example, two solid lines 1. and! This means that by setting and looking at the solid line L0 that indicates approximately the average value of the area between gaps, it is possible to use this as a reference distribution characteristic of the spacing and tapale spacing. The solid line L0 to be set is taken as the standard distribution characteristic of the spacing. In addition, in Figure 3,
The range of 60 μs or less is blank, but this is based on the response preparation time of the ground station. Note that the average of the entire squirting pulse interval is approximately 950 μS.

The data to be stored in the gap pulse interval memory 2 is based on the distribution characteristic shown by the solid line L0 in FIG.
It contains about 4000t-4f.

This number is set from the viewpoint of the trade-off between the error based on quantization and the operational accuracy, such as the gap to be written and the number of times the quantization step of the taper interval. The above-mentioned number is obtained by selecting double. Thus, for example, if the squirting pulse interval is 27
At 0 μs, the relative distribution rate is 0.055, 4000
Approximately 220 pieces of data will be stored.

Conversely, it can be said that the 21 pieces of data are set in advance taking into consideration the maximum number of squirter pulses that should be read out per second.

In this way, Sukitsuta Pulse has an 8-bit, 8-bit configuration with a maximum of 256
Provides ridge spacing.

In this way, the Sukitsuta pulse interval data stored in the Sukitsuta pulse interval data memory 2 using FROM is stored in accordance with the Sugitata pulse interval length at the address of the condition that H pieces are arranged in units of 54 μs from 60 μs to 2700 μs according to the relative distribution rate. .

The 12-bit random code consists of approximately 400 12-bit codes stored in the Sukitsuta pulse interval data memory 2.
Used as address specification 1g of 0 data, P
Outputs tapalus interval data with random probability of occurrence according to the N code. The data thus read clearly shows the relative distribution rate shown by the actual machine L0 in FIG.

The data read from the squitter pulse interval data memory 2 is transferred to a color/return circuit 3.The counter circuit 3 performs this color countdown every time the squitter pulse interval data of 8-bit configuration is input, and outputs a negative pulse countdown signal at the end of counting. Supply to 4.

The inverter 4 inverts the polarity of the countdown signal and transfers it to the D-type flip-flop circuit 5 and the counter circuit 3.
is supplied to the loading terminal LD of.

When the counter circuit 3 receives the output from the inverter 4, it is reset to a state in which it can count the next spacing pulse interval data, counts the next spacing pulse interval data, and repeats the process one after another.

In this way, the Q terminal output pulses outputted from the D-type flip-flop circuit 5 are used as squitter pulses whose pulse intervals are equal to those stored in the pulse interval data memory 2.

The sukitsuta pulse obtained in this way is the above-mentioned C
It is not affected by W and can maintain a stable transmission state.

〔Effect of the invention〕

As explained above, according to the present invention, by providing a means for synthesizing gaps and tapers without depending on thermal noise, gaps and tapers in a stable state without being disturbed by CW waves induced from attached equipment etc. are provided. This has the effect that it is possible to realize a gap pulse generator that can generate tap pulses, and also makes it possible to adopt a judgment that gives priority to interrogation pulses because the generation timing of the gap and tap pulses to be generated is determined.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a conventional tapalus generator,
FIG. 3 is a distribution characteristic diagram of squirter pulses of the DME device. 1...Random code generator, 2...
Skip, Tapulse interval data memory, 3... Counter circuit, 4... Inverter, 5...
D-type flikup 70 tubes, 6...mixer, 7...
... Variable gain amplifier, 8 ... Level detector, 9 ... Counter, 10 ... Pulse number voltage converter, 11 ... Comparator. Agent Patent Attorney Susumu Uchihara J -------Mi7γ 7-------I Nyoji - Auditorium 11-----ConlX Niji-y Kaya 211ffl

Claims (1)

[Claims] DME (Distance Measuring Eq.
In a squitter pulse generator that generates squitter pulses to be emitted from a ground station to an airborne station of a device (equipment), squitter pulse interval data indicating a time interval between the squitter pulses is set in advance based on its quantization step. a squitter pulse interval data storage means for storing the number of squitter pulse interval data in a set address with array characteristics corresponding to the relative distribution rate of the squitter pulse intervals; and a bit number set in advance corresponding to the number of addresses of the squitter pulses. random code generation means for generating a random code and using the random code as an addressing signal to read out the squitter pulse interval data stored in the squitter pulse data storage means; A squitter pulse generator comprising: squitter pulse forming means for forming a squitter pulse based on squitter pulse interval data.