KR101846971B1 - Method and Apparatus of Digital Signal Normalization for High Speed Frequency Hopping in Tactical Data Link - Google Patents

Abstract

According to the present invention, a method for digital signal normalization method for high-speed frequency hopping communication in a tactical data link includes the steps of: receiving a reception signal including a synchronization signal, a time refine (TR) signal, a header, and a tactical message; performing analog digital conversion (ADC) on the reception signal; and determining whether the reception signal in which the ADC is performed includes the TR signal. Even in the non-use of AGC of an RF unit, high-speed frequency hopping can be performed by normally transmitting and receiving a wide range power signal in a distance of several hundred meters to several hundred kilometers.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal normalization method and apparatus for high-speed frequency hopping communication in a tactical data link,

The present invention relates to a digital signal normalization method and apparatus for fast frequency hopping communication in a tactical data link.

The tactical data link used by the military requires an anti-jamming function due to the importance of the tactical message to transmit and receive. In high-speed hopping communication, frequency hopping is performed tens of thousands of times per second, and communication is performed for several tens of microseconds per frequency.

In such a high-speed frequency hopping communication, it is impossible to uniformly control the received signal power and synchronize with the conventional automatic gain control (AGC) performed in the RF unit. However, if AGC is not used, the power range of the received signal may be out of range of the analog-to-digital converter (ADC) of the modem, and the signal may be saturated and distorted. In addition, when forward error correction (hereinafter referred to as FEC) is input for demodulation and error correction for a digital signal after the ADC, it is impossible to demodulate the signal beyond the FEC input signal intensity range.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a digital signal normalization method and apparatus for fast frequency hopping communication in a tactical data link.

According to another aspect of the present invention, there is provided a digital signal normalization method for a high-speed frequency hopping communication in a tactical data link, comprising: receiving a reception signal including a synchronization signal, a time reference (TR) ; Performing ADC (Analog Digital Conversion) on the received signal; And a step of determining whether the reception signal on which the ADC is performed includes the TR signal. In addition, even when the RF part AGC is not used, a signal of a wide power can be normally transmitted / received at a distance of several hundreds of meters to several hundreds of kilometers .

In one embodiment, if the received signal is a signal including the TR signal, measuring the signal strength per one pulse to obtain signal strength of 15 pulses.

In one embodiment, obtaining the median of the signal strengths of the fifteen pulses, wherein the median is for a plurality of TR pulses in order to prepare for a signal or jamming signal of a strong other communication system in a frequency sharing environment ≪ / RTI > obtained to perform digital signal strength normalization.

In one embodiment, the method may further include normalizing the received signal value by dividing the received signal value after the ADC with respect to the header and the tact message after the TR signal by the obtained intermediate value.

In one embodiment, multiplying the received signal value by a constant value? To fit an input value for forward error correction (FEC); And performing an FEC on the received signal value multiplied by the constant value [alpha].

In one embodiment, performing an error check (CRC) on the header and the tactic message; And completing demodulation on the header and the tactical message.

In one embodiment, the header and the tactical message may include a signal due to saturation of an amplifier (Amp) and an analog-to-digital converter (ADC) of the RF unit according to the AGC (Automatic Gain Control) In order to minimize the distortion, a phase shift keying (PSK) modulation scheme can be used to modulate. The demodulation of the header and the tact message may be performed using the demodulation scheme of the PSK sequence.

According to an aspect of the present invention, there is provided a digital signal normalization apparatus for a high-speed frequency hopping communication in a tactical data link, the apparatus including: a receiver for receiving a reception signal including a synchronization signal, a time- An RF unit; And a modem unit for performing ADC (Analog Digital Conversion) on the received signal and determining whether the received signal, which is performed by the ADC, includes the TR signal.

In one embodiment, when the received signal is a signal including the TR signal, the modem unit measures a signal strength per pulse to obtain a signal strength of 15 pulses, and calculates an intermediate value of the signal strength of the 15 pulses and a signal strength normalization section for acquiring a median of the signal intensity. Here, the intermediate value may be obtained in order to perform digital signal strength normalization on a plurality of TR pulses in order to prepare for a strong communication system signal or a jamming signal in a frequency sharing environment.

In one embodiment, the signal strength normalization unit may further be configured to normalize the received signal value by dividing the received signal value after the ADC by the obtained intermediate value for the header and the tact message after the TR signal have.

In one embodiment, the modem unit multiplies the received signal value by a predetermined value (alpha) so as to match an input value for FEC (Forward Error Correction), and multiplies the received signal value multiplied by the constant value And a demodulator for performing FEC on the FEC.

In one embodiment, the demodulator may be configured to perform an error check (CRC) on the header and the tactical message, and to complete demodulation on the header and the tactical message.

In one embodiment, the header and the tactical message may include a signal due to saturation of an amplifier (Amp) and an analog-to-digital converter (ADC) of the RF unit according to the AGC (Automatic Gain Control) In order to minimize the distortion, a phase shift keying (PSK) modulation scheme is used and modulated. The demodulation unit may be configured to demodulate the header and the tact message using the demodulation scheme of the PSK sequence.

According to the present invention, even when the RF part AGC is not used, it is possible to normally transmit / receive signals of a wide power at a distance of several hundreds of meters to several hundreds of kilometers to enable fast frequency hopping.

Further, according to the present invention, as the AGC of the conventional RF unit becomes unnecessary, it is possible to expect advantages in terms of hardware price, volume, and complexity such as variable attenuator of the RF unit, reduction of Amp number and elimination of AGC control unit, have.

1 shows a configuration of an apparatus for high-speed frequency hopping communication in a tactical data link including an RF unit and a modem unit in the context of the present invention.
2 illustrates a configuration of a digital signal normalization apparatus for fast frequency hopping communication in a tactical data link according to the present invention.
FIG. 3 shows a structure of a timeslot message of a received signal including a synchronization signal, a time refine (TR) signal, a header, and a tactical message according to the present invention.
4 shows a flow diagram of a digital signal normalization method for fast frequency hopping communication in a tactical data link according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It will be possible. The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for similar elements in describing each drawing.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. The term "and / or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Should not.

The suffix "module "," block ", and "part" for components used in the following description are given or mixed in consideration of ease of specification only and do not have their own distinct meanings or roles .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Hereinafter, a digital signal normalization method and apparatus for high-speed frequency hopping communication in a tactical data link according to the present invention will be described.

In this regard, the tactical data link will first be described as follows. Currently the most widely deployed advanced tactical data link in the world is Link-16. Link-16 performs about 77,000 fast frequency hopping per second, which means changing the frequency every 13μs. That is, the length of one pulse is 13 μs, and the frequency is changed for each pulse. There is no system that performs high-speed frequency hopping as described above for the communication system developed in Korea. The tactical data link system up to now does not have the frequency hopping function. Recently, due to the importance of tactical messages transmitting / receiving the domestic tactical data link system, anti-jamming function like Link-16 is required.

One of the limitations in high-speed frequency hopping communication is that the time of a signal transmitted from one frequency is very short, which is several tens of microseconds which is one pulse time, and it is difficult to adjust the power of a received signal through the RF part AGC. Tactical data links usually transmit signals at the same power to each communication terminal, but the power range of the received signal is very wide because the communication distance is at least several hundred meters to several hundreds of kilometers. In particular, since 12 seconds are divided into units of 1536 timeslots and one terminal per time slot performs transmission and the remaining terminals use Time Division Multiple Access (TDMA), one time slot time of 7.8125 ms And the power of the received signal is abruptly changed according to the distance from the transmitting terminal. If the power range of the signal is too high, the RF saturation of the Amp of the RF unit and the ADC of the modem unit occurs, and after the ADC it is out of the FEC input range for demodulation and error correction of the digital signal, do.

In the case of non-hopping or low-speed data link communication developed in Korea, the RF unit measures the power of the received signal using the dummy message at the beginning of the transmission signal, and feeds back the AGC function to adjust the attenuator in the RF unit The received signal power was adjusted to be constant. In this regard, FIG. 1 shows a configuration of an apparatus for high-speed frequency hopping communication in a tactical data link including an RF unit and a modem unit in the context of the present invention. 1, the fast frequency hopping communication apparatus 100 measures a dummy message power at the initial stage of a received signal through an AGC controller in the RF unit 110 and outputs a variable attenuator And the power is constantly adjusted. With this AGC, after the dummy message, the message can be received and demodulated with a constant power. Meanwhile, the modem unit 120 includes an analog digital converter (ADC) and a demodulator for converting an analog signal into a digital signal. Meanwhile, the demodulator can perform forward error correction (FEC).

However, the AGC of the RF unit 110 requires a physical delay time of the filter existing on the path of the received signal and a time of several microseconds for measuring and controlling the received signal power. In order to control the received signal power within a reliable range, it takes at least 10 μs or more since a minimum of 2 or 3 AGCs must be performed. In the case of the conventional non-hopping or low-speed hopping, it is not a big problem to allocate the time of about 10 μs to the AGC. However, in high-speed hopping communication where the frequency changes every tens of microseconds (13 μs in Link- It is impossible to detect the signal with the data of the remaining time and adjust the time synchronization between the terminals.

Meanwhile, the present invention proposes a method capable of performing communication without performing AGC, which is performed by a conventional RF unit, for high-speed frequency hopping communication. When the AGC is not performed in the RF section, the power range of the received signal is very large and the ADC saturation phenomenon of the RF amplifier and the modem section occurs. In order to minimize the influence of the signal distortion on the signal, a PSK method is used to modulate the signal at the angle of the signal except for ASK, QAM and the like, which are sensitive to the magnitude of the signal. When the saturation occurs due to the strong power of the received signal, the distance between the terminals is very close. In this case, the signal to noise ratio (SNR) is very good. It was found through experiment that the level of demodulation is possible. The problem is that the use of forward error correction (FEC) to improve modem demodulation performance in modern communication systems is essential in demodulation techniques, and the input range of FEC is limited. Even if the saturation phenomenon is minimized by using the PSK modulation method, if the signal power is not adjusted in the RF section because the AGC is not used, there arises a problem that the signal strength is out of the FEC input range in the demodulation process after the ADC, so that demodulation is impossible. In order to solve this problem, a digital signal intensity normalization technique after the ADC has been devised, and the overall system configuration diagram thereof is shown in FIG.

That is, FIG. 2 illustrates a configuration of a digital signal normalization apparatus for high-speed frequency hopping communication in a tactical data link according to the present invention. As shown in FIG. 2, the digital signal normalization apparatus 200 includes an RF unit 210 and a modem unit 220. The RF section 210 includes an amplifier Amp, a first filter, a mixer, and a second filter. At this time, a reception signal including a synchronization signal, a time refine (TR) signal, a header, and a tact message is low-noise amplified by an amplifier Amp, passes only a desired RF band signal by a first filter, Band signals. Next, the mixer frequency-converts the received signal into a baseband signal of a desired band, a second filter passes only the baseband signal of the desired band, and filters out signals of the remaining bands do.

Next, the modem unit 220 includes an analog-to-digital converter (ADC) 221, a signal strength normalization unit 222, and a demodulator 223. The ADC 221 performs ADC (Analog Digital Conversion) on the received signal. Also, the modem unit 220 determines whether the received signal in which the ADC is performed includes the TR signal.

Referring to FIG. 2, the AGC control unit of the RF unit is removed in comparison with the configuration of FIG. 1, which is advantageous in terms of volume, price, and complexity of the RF unit. After the ADC of the modem unit, By adjusting the signal strength to be the same, the FEC input range was not exceeded.

A more detailed description of the digital signal strength normalization is as follows. As described above, the tactical data link is divided into 1536 time slots for 12 seconds, and the transmitting terminal is changed for each time slot to transmit the message. Normalization is performed using the fact that the power of the received signal is maintained because the distance between the terminals is almost constant since the time of the time slot is very short as 7.8125 ms even if the transmitting / receiving terminal moves during one time slot time . The message structure for sending / receiving in one time slot is shown in FIG. That is, FIG. 3 shows a structure of a time slot message of a received signal including a synchronization signal, a time refine (TR) signal, a header, and a tactical message according to the present invention. As shown in FIG. 3, the received signal is transmitted / received in the order of Sync, Time Refine, Header, Tactical Message, and Propagation Delay. The first synchronization message is used to synchronize the transmission / reception terminals. After synchronization, detailed synchronization is achieved through the TR signal. The power of the TR signal is measured at a digital terminal after the ADC. In high-speed frequency hopping communication, the frequency is changed per pulse. As described above, the length of one pulse is several tens of microseconds since it jumps several tens of seconds per second. At the receiving terminal, the intensity of the signal received after the ADC of the TR signal is measured and stored in units of one pulse. In this case, if the signal strength after the ADC of the header and tactical message received is divided by the measured signal strength, the value is about 1 regardless of whether the received signal power is large or small depending on the distance between the terminals. That is, regardless of the power of the received signal, the signal has a constant value. Therefore, after the normalization of the digital signal strength, all signals are weighted by the FEC input.

Also, a method of measuring the intensity of the TR signal is proposed. As frequency resources become depleted, several systems want to share the frequency and in this environment signals from other systems (especially those with very large powers such as radar) or powerful enemy jamming signals can be received. When the power of the TR signal is measured, strong signals of other systems or jammers are received, and when the signal strength normalization is performed based on this strong error, a large error may occur. The TR signal of the currently developed tactical data link system consists of a total of 15 pulses. The signal power per pulse of each of 15 pulses is measured and signal strength normalization is performed using the median of 15 pulse signal powers. When normalizing by the average of 15 pulse signal power, abnormal data can be measured by raising the average when there is a signal of very large power such as radar or jamming.

The above description will be described in terms of the modem unit 220 including the ADC 221, the signal strength normalization unit 222 and the demodulation unit 223 as follows.

The signal strength normalization unit 222 measures the signal strength of one pulse and measures the signal strength of 15 pulses when the received signal includes the TR signal to perform digital signal strength normalization. Also, the signal strength normalization unit 222 obtains a median of the signal strengths of the 15 pulses. That is, in order to prepare for a signal or a jamming signal of a strong other communication system in a frequency sharing environment, an average value is obtained, not an average value. The signal strength normalization unit 222 normalizes the received signal value by dividing the received signal value after the ADC with respect to the header and the tact message after the TR signal by the obtained intermediate value.

The demodulator 223 multiplies the received signal value by a predetermined value (alpha) so as to match an input value for forward error correction (FEC). Also, the demodulator 223 performs FEC on the received signal value multiplied by the constant value [alpha]. Also, the demodulator 223 performs an error check (CRC) on the header and the tactical message, and completes demodulation on the header and the tactic message.

Meanwhile, the header and the tactical message may be generated by saturation of an amplifier (Amp) and an analog-to-digital converter (ADC) in the RF unit according to the AGC (Automatic Gain Control) In order to minimize the signal distortion, a phase shift keying (PSK) modulation scheme is used and modulated. The demodulation of the header and the tact message is performed using the demodulation scheme of the PSK sequence.

In the foregoing, a digital signal normalization apparatus for fast frequency hopping communication in a tactical data link according to the present invention has been described. Hereinafter, a digital signal normalization method for fast frequency hopping communication in a tactical data link according to another aspect of the present invention will be described. It should be noted that the digital signal normalization apparatus and the digital signal normalization method may be mutually referenced.

In this regard, Figure 4 shows a flow diagram of a digital signal normalization method for fast frequency hopping communication in a tactical data link according to the present invention. As shown in Figs. 3 and 4, the procedure is a flow chart of the reception processing from the TR message after synchronization in the transmission / reception message structure of one timeslot (see Fig. 3). As shown in FIG. 4, the digital signal normalization method includes a received signal receiving step S100, an ADC performing step S110, and a TR signal judging step S120. The digital signal normalization method further includes a pulse strength measurement step S130, a pulse intensity intermediate value acquisition step S140, and a normalization execution step S150. The digital signal normalization method may further include an FEC input value adjustment step S160, an FEC performing step S170, an error check step 180, and a demodulation completion step S190. The steps described above will be described in detail.

Receiving signal reception step S100 - Receiving a reception signal including a time refine (TR) signal, a header, and a tact message.

ADC execution step (S110) - The received signal is inputted in the order of TR, header, and tactical message, and the ADC processes it and converts it into a digital signal.

Whether or not the TR signal is included (S 120) - It is determined whether the received signal that the ADC has performed includes the TR signal. In this regard, referring to FIG. 3, since the signal immediately after synchronization is a TR signal, it can be determined whether the received signal is a TR signal after the ADC.

Pulse intensity measurement step (S130) - In the case of the TR signal, the signal intensity per pulse is measured to measure the signal intensity of 15 pulses. Here, the number of pulses to be measured is not limited to 15, but may be variously modified depending on the application. It is also possible to vary variously according to the time length of the time slot. That is, the number of pulses to be measured may be increased as the time interval of the time slot increases. Also, the number of pulses can be determined to be inversely proportional to the propagation delay time for the same time slot.

Pulse intensity intermediate value acquisition step (S140) - The median value of the signal intensity of the 15 pulses is obtained and stored. Here, the intermediate value is obtained in order to perform digital signal strength normalization for a plurality of TR pulses in order to prepare for a signal of a different communication system or a jamming signal in a frequency sharing environment.

Normalization Performing Step S150 - Normalizing the received signal value by dividing the received signal value after the ADC with respect to the header and the tact message after the TR signal by the obtained intermediate value. That is, after the TR signal, the header and the tact message can be normalized by dividing the received signal value after the ADC by the median value obtained in the step of acquiring the intermediate pulse intensity value (S140).

FEC input value adjustment step (S160) - The received signal value is multiplied by a predetermined value (alpha) so as to match an input value for FEC (Forward Error Correction).

FEC performing step (S170) - FEC is performed on the received signal value multiplied by the predetermined value [alpha].

Error check step 180: Performs an error check (CRC) on the header and the tactical message.

Demodulation Completion Step (S190) - Demodulation of the header and the tact message is completed. At this time, the header and the tactical message minimize the signal distortion due to the saturation of the amplifier (Amp) and the ADC (Analog Digital Converter) of the RF unit according to the AGC (Automatic Gain Control) of the RF (Radio Frequency) A phase shift keying (PSK) modulation scheme is used and modulated. The demodulation of the header and the tact message may be performed using the demodulation scheme of the PSK sequence.

As a result of the simulation based on the above-mentioned invention, it was confirmed that even when AGC of the RF part is not used, signals of a wide power corresponding to a distance of several hundred meters to several hundred km are normally transmitted / received. Could know.

On the other hand, when a high-speed frequency hopping communication is desired for anti-jamming performance in a tactical data link, it is impossible to communicate with the RF sub-AGC method. Therefore, it is possible to communicate by using modulation scheme of PSK series and normalization of digital signal intensity in a structure that does not use AGC in RF section.

In addition, as the AGC of the conventional RF part becomes unnecessary, it is expected that the advantages in terms of hardware price, volume, and complexity such as variable attenuator of RF part, reduction of Amp number, and elimination of AGC control part and ease of design can be expected.

According to a software implementation, not only the procedures and functions described herein, but also each component may be implemented as a separate software module. Software code can be implemented in a software application written in a suitable programming language. The software code is stored in a memory and can be executed by a controller or a processor.

Claims (6)

A digital signal normalization method for fast frequency hopping communication in a tactical data link,
Receiving a reception signal including a synchronization signal, a time refine (TR) signal, a header, and a tactical message;
Performing ADC (Analog Digital Conversion) on the received signal;
Determining whether the received signal in which the ADC is performed includes the TR signal;
Measuring a signal intensity of one pulse when the received signal is a signal including the TR signal, and measuring a signal intensity of 15 pulses;
Obtaining a median of the signal strength of the 15 pulses; And
And normalizing the received signal value by dividing the received signal value after the ADC with respect to the header and the tact message after the TR signal by the obtained intermediate value,
A digital signal normalization method for fast frequency hopping communication in a tactical data link. The method according to claim 1,
Wherein the intermediate value is obtained in order to perform digital signal strength normalization for a plurality of TR pulses in order to prepare for a signal of a different communication system or a jamming signal in a frequency sharing environment,
A digital signal normalization method for fast frequency hopping communication in a tactical data link. delete 3. The method of claim 2,
Multiplying the received signal value by a constant value (alpha) to fit an input value for forward error correction (FEC); And
Further comprising performing an FEC on the received signal value multiplied by the constant value [alpha]
A digital signal normalization method for fast frequency hopping communication in a tactical data link. 5. The method of claim 4,
Performing an error check (CRC) on the header and the tactical message; And
Further comprising: completing demodulation on the header and the tactical message.
A digital signal normalization method for fast frequency hopping communication in a tactical data link. 6. The method of claim 5,
The header and the tactical message are used to minimize signal distortion due to saturation of the amplifier (Amp) and the ADC (Analog Digital Converter) of the RF unit according to the AGC (Automatic Gain Control) A phase shift keying (PSK) modulation scheme is used and modulated,
Wherein the demodulation of the header and the tact message is performed using a demodulation scheme of the PSK sequence,
A digital signal normalization method for fast frequency hopping communication in a tactical data link.

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