KR102104617B1 - Modem of fly-away terminal transceiver for satellite data communication using turbo-product code - Google Patents

Abstract

The present invention relates to a terrestrial terminal for satellite data communication capable of communicating with a geostationary satellite. More specifically, the present invention relates to a modem for a fly-away terminal for the satellite data communication using a turbo-product code (TPC) scheme, capable of satisfying performance required in a next military satellite communication system while complying with regulations of International Telecommunication Union Radiocommunication Sector (ITU-R), MIL-STD-188-164A, and MIL-STD-188-164A. According to an embodiment of the present invention, the modem for the fly-away terminal for the satellite data communication has a main/sub reflective plate of an antenna, which is formed of a magnesium material for compactness and lightness, thereby minimizing the weight thereof. In addition, a modem part is designed by applying a turbo product code (TPC) instead of a low density parity check (LDPC) code to increase the variance of a traffic section, in addition to a DVB-S2 based design. An IC of an AHA company is used to solve complexity, thereby reducing an amount of a logic actually implemented. In addition, a cascaded integrator comb (CIC) filter is applied to support even an interpolation rate 512 to allow the selection of various bandwidths.

Description

Modem for a fly-away terminal for satellite data communication using the TPC method {MODEM OF FLY-AWAY TERMINAL TRANSCEIVER FOR SATELLITE DATA COMMUNICATION USING TURBO-PRODUCT CODE}

The present invention relates to a terrestrial terminal for satellite data communication capable of communicating with a geostationary satellite, and more specifically, the International Telecommunication Union Regulation (ITU-R), the United States Department of Defense Military Specification (MIL-STD-188-164A) and Europe Modem for a fly-away terminal for satellite data communication using the Turbo-Product Code (TPC) method that can satisfy the performance required by the next military satellite communication system while complying with the Telecommunication Standards Association (ETSI EN 302 307) standard. It is about.

In general, satellite communication is performed by retransmitting a signal transmitted from a terrestrial terminal or earth station back to the ground through a satellite and receiving it from an opposite terminal or earth station. These satellite communications are classified into low-orbit, medium-orbit and geostationary communications according to the orbital height of the satellite, and the cost of signal transmission is cheaper than that of using existing line networks, and it is easier to construct new line networks and to perform long-distance communication. There is an advantage.

In other words, such satellite communication is not only wide-area capable of covering a large area compared to terrestrial communication, but also broadcastability that can transmit information to multiple earth stations at the same time, ease of access after the service is started, and broadbandness that can use a relatively wide frequency band. It has excellent properties. Due to this advantage, despite long transmission delays, utilization in portable satellite communication, including military communication, and public / safety / disaster communication has been highlighted.

However, in the case of satellite communication, especially in the geostationary communication system, since the distance between the space station stationary satellite and the earth station satellite terminal is greater than tens of thousands of km, the attenuation of the transmission and reception signals according to the distance and climate is very large. Also, since many satellites of a space station must transmit and receive only to a target satellite without mutual interference, the design of transmitting and receiving in satellite communication is very important.

Accordingly, the next military satellite while complying with the standards of the International Telecommunication Union (ITU-R), the U.S. Department of Defense Military Specification (MILItary-STanDard), the US Federal Communications Commission (Federal Communication Commission), and the European Telecommunications Standards Association A research and development of a transceiver capable of miniaturization, light weight, and low power consumption that satisfies the performance required by a communication system and can also improve user convenience between movement, installation, and operation of equipment is required.

KR 10-0580591 B1, 2006. 05. 09. KR 10-2005-0038993 A, 2005. 04. 29. KR 10-1860012 B1, 2018. 05. 15.

Byung-Jun Park, Chun-Won Kim, Won-Sang Yoon, and Sung-Jae Lee, "Fly-away Terminal Antenna & RF System Design for Ka Band Satellite Communication", Journal of the KIMST, Vol 17, No. 4, pp. 485-491, 2014. Chun-Won Kim, Myeong-Jun Park, Won-Sang Yoon, and Sung-Jae Lee, "Ka Band Military Satellite Communication Terrestrial Transmitter Design", THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. 2014 Apr .; 25 (4), 393 ~ 400.

Therefore, the present invention complies with the International Telecommunication Union Regulation (ITU-R), the U.S. Department of Defense Military Specification (MIL-STD-188-164A) and the European Telecommunication Standards Association (ETSI EN 302 307) standard, while the next military satellite communication Provided is a modem for a fly-away terminal for satellite data communication using a Turbo-Product Code (TPC) method that can satisfy the performance required by the system.

The present invention according to an aspect of the present invention for achieving the above object is an encoding unit for receiving a transmission signal in units of blocks and encoding it using a Turbo Product Code (TPC), which is one of forward error correction codes; A modulator for modulating a transmission signal encoded by the encoder; A first filter unit that matches the transmitted signal modulated by the modulation unit using a Root Raised Cosine (RRC) filter; An up-sampling unit that increases a sampling frequency of an output signal of the first filter unit by using a CIC (Cascaded Integrator Comb) filter; A first mixing unit mixing the output signal of the up-sampling unit and a frequency provided from a NCO (Numerically Controlled Ocsillator) and converting it into an intermediate frequency signal band; And a digital / analog (D / A) converter for converting the digital signal output from the first mixing unit to an analog signal and outputting it to a transmitting / receiving unit connected to an antenna communicating with a satellite. do.

In addition, the present invention according to another aspect for achieving the above object is an analog to receive the input signal from the transceiver to convert the signal of the Ka band received from the antenna communicating with the satellite and low-frequency amplification and down-frequency conversion to a digital signal / Digital converter; A second mixing unit which mixes a frequency of NCO (Numerically Controlled Ocsillator) with a signal output from the analog / digital converter to convert a signal in an intermediate frequency band into a baseband signal; A down-sampling unit that lowers the sampling frequency of the signal output from the second mixing unit using a cascaded integral filter (CIC) filter; A second filter unit that matches the signal output from the down-sampling unit using a Root Raised Cosine (RRC) filter; A demodulator demodulating the signal output from the second filter unit; And a decoder for detecting and correcting an error included in the signal output from the demodulator using a TPC (Turbo Product Code).

In addition, according to another aspect of the present invention for achieving the above object, an encoding unit that receives a transmission signal in block units and encodes it using a Turbo Product Code (TPC), one of forward error correction codes, and the encoding unit A modulator for modulating the transmitted signal encoded in the first unit, and a first filter unit for matching the transmitted signal modulated by the modulator using a Root Raised Cosine (RRC) filter and a CIC (Cascaded Integrator Comb) filter An up-sampling unit for increasing the sampling frequency of the output signal of the first filter unit, and a first mixing unit for mixing the output signal of the up-sampling unit and a frequency provided from a NCO (Numerically Controlled Ocsillator) and converting it into an intermediate frequency signal band, The digital signal output from the first mixing unit is converted into an analog signal and output to a transmitting / receiving unit that is transmitted to an antenna communicating with a satellite. A transmission unit including a digital / analog (D / A) converter; And an analog / digital converter for converting the received signal from the transceiver to a digital signal, and mixing the frequency of a NCO (Numerically Controlled Ocsillator) with the signal output from the analog / digital converter to convert the signal in the intermediate frequency band into a baseband signal. A second mixing unit for converting the signal, and a down-sampling unit for lowering the sampling frequency using a CIC (Cascaded Integrator Comb) filter for the signal output from the second mixing unit, and the down using a RRC (Root Raised Cosine) filter A second filter unit that matches the signal output from the sampling unit, a demodulator that demodulates the signal output from the second filter unit, and an error included in the signal output from the demodulator is TPC (Turbo Product Code). Provided is a modem for a fly away terminal for satellite data communication including a receiver including a decoding unit for detecting and correcting errors using the same.

In addition, the transceiver receives an intermediate frequency band signal from the modem and upconverts it to the Ka band, and then uses a dual equilibrium structure of pHEMT (pseudomorphic High Electron Mobility Transistor) MMIC (Monolithic Microwave Integrated Circuit) to the antenna through high power amplification. I can send it.

In addition, the antenna has a high-gain, small-volume, dual-offset gregorian type reflector, a corrugated type feed horn, a pleated polarizer for generating circular polarization, and a transmission / reception signal. It may include an orthomode transducer (OMT) separating the.

In addition, the reflector may be made of magnesium material.

In addition, the transmitting and receiving unit receives an intermediate frequency output from the modem, an up-frequency converter for up-converting the frequency to the Ka band (Ka-band); And a high-power amplifying unit for amplifying the up-converted frequency by the up-frequency converting unit to a high power by using a dual equilibrium structure, pHEMT (Pseudomorphic High Electron Mobility Transistor) MMIC (Monolithic Microwave Integrated Circuit). .

In addition, the uplink frequency conversion unit frequency synthesis unit for generating a local signal necessary for frequency conversion; A frequency converter may generate a signal in the Ka band by synthesizing an intermediate frequency signal output from the modem and a local signal of the frequency synthesizer.

In addition, the transmitting and receiving unit is a tuned radio frequency receiver (Tuned Radio Frequency, TRF) for receiving the Ka band signal received from the antenna; And a low noise block down coverter (LNB) for low-noise amplification and down-frequency conversion of the Ka band signal received through the tuned radio frequency receiver and outputting it to the modem.

In addition, the low-noise down-frequency converter is a low-noise amplifying unit for amplifying the Ka band signal received by the tuned radio frequency receiver; A frequency converter that down-converts the Ka band signal received through the low-noise amplifier to an intermediate frequency; And a frequency synthesizer generating a signal necessary for frequency conversion of the Ka band by the frequency converter, and generating a local frequency signal corresponding to twice the frequency generated using a frequency doubler.

According to the modem for the fly-away terminal for satellite data communication according to an embodiment of the present invention, the weight of the main / sub reflector of the antenna is minimized by using magnesium material for miniaturization and weight reduction.

In addition, in order to increase the variability of the traffic section in the DVB-S2 based design, the modem unit uses TPC (Turbo-Product Code), one of the forward error correction codes (FEC), instead of the low density parity check (LDPC) codes. Encoding and decoding were implemented by applying, and to solve the complexity problem, AHA's IC was used to save the amount of actual implementation logic. The CICCascaded Integrator Comb) filter that supports up to 512 interpolation rates was applied to select various bandwidths.

Therefore, the present invention complies with the International Telecommunication Union Regulation (ITU-R), the U.S. Department of Defense Military Specification (MIL-STD-188-164A) and the European Telecommunication Standards Association (ETSI EN 302 307) standard, while the next military satellite communication Satisfying the performance required by the system, it can be applied to a fly away terminal for satellite data communication where tactical mobility that is moved and installed by two carriers is important.

1 is a block diagram showing a fly away terminal for satellite data communication using a TPC scheme according to an embodiment of the present invention.
FIG. 2 is a simplified diagram for describing the antenna illustrated in FIG. 1.
3 is a view illustrating a dual offset Gregorian type reflector antenna according to the present invention.
4 is a view illustrating a feeding horn, a polarizer and an orthogonal mode converter according to the present invention.
5 is a block diagram illustrating a transmitter according to the present invention.
6 is a block diagram illustrating a receiver according to the present invention.
7 is a block diagram illustrating a configuration of a transmitter of a modem according to the present invention.
8 is a block diagram illustrating a configuration of a receiver of a modem according to the present invention.
9 to 11 are diagrams showing simulation results of each TPC modulation method of a fly away terminal for satellite data communication using a TPC method according to an embodiment of the present invention.
12 is a diagram illustrating a test configuration for measuring the performance of a fly away terminal for satellite data communication using a TPC method according to an embodiment of the present invention.
13 is a view showing a measurement result of a transmitting and receiving antenna of a fly away terminal for satellite data communication using a TPC method according to an embodiment of the present invention.
14 is a view showing a transmission output result of a fly away terminal for satellite data communication using a TPC method according to an embodiment of the present invention.
15 is a view showing a reception gain and a noise index measurement result of a fly away terminal for satellite data communication using a TPC method according to an embodiment of the present invention.
FIG. 16 is a view showing transmission / reception unnecessary wave measurement results of a flyaway terminal for satellite data communication using a TPC method according to an embodiment of the present invention.
18 and 19 are diagrams showing a result of measuring the performance of a modem unit of a fly away terminal for satellite data communication using a TPC method according to an embodiment of the present invention by a PTP BER test.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the embodiments of the present invention make the disclosure of the present invention complete, and the scope of the invention to those skilled in the art It is provided to inform you completely. The same reference numerals in the drawings refer to the same elements.

1 is a block diagram briefly illustrating a configuration of a fly away terminal for satellite data communication using a Turbo-Product Code (TPC) method according to an embodiment of the present invention.

Referring to FIG. 1, a fly away terminal for satellite data communication according to an embodiment of the present invention is a terrestrial (earth station) terminal for satellite data communication capable of communicating with a geostationary satellite, and a transmitting and receiving unit communicating with a stationary satellite through the antenna 1 (10) and a modem (20).

FIG. 2 is a diagram briefly illustrated to describe the antenna illustrated in FIG. 1.

Referring to FIG. 2, the antenna 1 according to the present invention is a satellite terminal antenna for transport, receives a Ka band signal (reception signal) from a satellite, sends it to the receiving unit 12, and transmits a Ka band signal (transmitting from the transmitting unit 11). It is a device that receives signals) and radiates them toward the satellite.

The antenna 1 is composed of a dual polarized feed horn structure, and circular polarization is LHCP and RHCP, and linear linear waves can be transmitted and received in a manner of using the same frequency as vertical polarization and horizontal polarization. For example, high-gain, small-volume, dual-offset gregorian type reflectors 1a, 1b, corrugated feed horns 1c, and pleats for circular polarization generation And a polarizer 1d and an orthomode transducer (OMT) 1e for separating transmission and reception signals.

In this way, the antenna 1 according to the present invention has a high gain, so even if the output of the transmitter 11 is small, it may affect neighboring satellites. Accordingly, ITU-R and MIL-STD-188-164A recommend that the antenna gain pattern be designed to be less than or equal to a certain value for each electrical size of the antenna, and it was designed as shown in [Table 1] below.

Parameter Target Designed Frequency Ka-band
Antennal Gain Tx 44.0dBi 46.0dBi Rx 41.5dBi 42.3dBi Co-pol / Cross-pol ITU-R Antenna Noise Temperature 150 ° K 134.7 ° k
Polarization characteristics Tx LHCP Rx RHCP

3 is a view illustrating a dual offset Gregorian type reflector antenna according to the present invention.

3, the elliptical double offset Gregorian type reflector antenna structure is applied to the reflectors 1a and 1b according to the present invention. In the case of a general parabolic antenna, there is a disadvantage in that the volume is increased by a focal length, but the antenna 1 according to the present invention has a dual reflector structure, that is, a dual offset Gregorian type reflector, thereby increasing the overall antenna height compared to a general parabolic antenna. It has the advantage of being lowered.

) 50%를 기준으로 송신이득 44.0dBi, 수신이득 41.5dBi를 만족하도록 하기 위한 반사판 지름은 0.75m로 결정하였다. In the design of the reflecting plates 1a, 1b, the opening area and the diameter of the main reflecting plate 1a are obtained, and the size of the auxiliary reflecting plate 1b, the irradiation angle of the feeding horn 1c, and the rotating angle of the feeding horn 1c are used by using this. Determine by using, axis rotation angle, etc. For example, the effective opening surface area D of the main reflector 1a is determined by Equation 1 below, and the opening surface efficiency (

) Based on 50%, the reflector diameter was determined to be 0.75 m to satisfy the transmission gain of 44.0 dBi and the reception gain of 41.5 dBi.

For example, in the present invention, the length of the antenna 1 is mounted on the body of the fly away terminal for satellite data communication 619.13mm, the size of the secondary reflector 1b is 185mm, the irradiation angle of the feeding horn 1c is 37 °, the axis rotation angle β was 53.207 °, and the rotation angle α of the feeding horn 1c was 77.206 °.

4 is a view illustrating a feed horn, a polarizer and an orthogonal mode converter according to the present invention, (a) is a feed horn, (b) is a polarizer, and (c) is an orthogonal mode converter.

As shown in Fig. 4 (a), the feeding horn 1c according to the present invention has circular symmetry in broadband to satisfy the gain of the reflector antenna and the radiation pattern requirements recommended by ITU-R and MIL-STD-188-164A. Corrugated type feeding horn with low side lobe characteristics of was applied.

The corrugated type feed horn applied to the feed horn 1c according to the present invention generates a TM ₁₁ mode by the taper angle of the feed horn inside the TE ₁₁ mode excited by the input waveguide, and the width and depth of the inner corrugated And, various modes such as the TE ₁₀ mode are additionally generated according to the interval to implement the HE ₁₁ mode in the opening surface. The HE ₁₁ mode has the characteristic of evenly distributing the signal in all directions in the opening surface. This emits radio waves into the atmosphere to realize the circular symmetrical radiation pattern, low side lobe, and high cross-polarization separation characteristics.

As shown in (b) of FIG. 4, the polarizer 1d according to the present invention has excellent transmittance performance in broadband to satisfy transmit / receive ratio performance of the MIL standard and transmission LHCP and reception RHCP generation of a flyaway terminal for satellite data communication. A pleated polarizer was applied.

The pleated polarizer is a component that generates circular polarization in the output port when linear polarization is applied to the input port. The principle of the circular polarization is to create a corrugated groove in the square waveguide light wall to generate a linear polarization and horizontal polarization applied to the input port. It is divided by, and the size difference between polarizations is 0dB and the phase difference is close to 90 °, which is a device that generates left-handed and right-handed polarized waves in the transmission band.

For example, the pleated polarizer applied to the polarizer 1d according to the present invention was designed to have an axial ratio of 1.5 dB or less and a standing wave ratio of 2.0: 1 or less to satisfy MIL-STD-188-164A.

As shown in (c) of FIG. 4, the orthogonal mode converter 1e according to the present invention separates the Ka band satellite transmission / reception signals of the flyaway terminal for satellite data communication, and is connected to the polarizer 1d to perform vertical and horizontal polarization. Separate the transmit and receive calls by inserting the WR-28 square waveguide in the vertical direction of the coexisting circular waveguide and the WR-42 square waveguide in the horizontal direction. In this case, the common waveguide type common port is designed to pass through both the transmission and reception bands of the Ka band, and only the transmission and reception signals are transmitted to the transmission and reception ports. As an example, the transmission, reception, and common ports are designed to have a standing wave ratio of 1.5: 1 or less and a separation of transmit and receive signals of -25dB or less using a stepped impedance matching structure and a coupling slot.

As shown in FIG. 1, the transmission / reception unit 10 according to the present invention includes a transmission unit 11 and a reception unit 12.

5 is a block diagram illustrating a transmitter according to the present invention.

1 and 5, the transceiver 10 according to the present invention receives the intermediate frequency output from the modem 20 and up-converts the frequency to Ka-band and then double-balances it. The transmitter 11 transmits a signal to the antenna 1 through high-power amplification using a structured pHmorph (High Electron Mobility Transistor) pHMIC (Monolithic Microwave Integrated Circuit) MMIC, and the Ka band signal received from the antenna 1 And a receiver 12 that transmits to the modem 20 by performing low-noise amplification and down-frequency conversion.

As shown in FIG. 5, the transmitter 11 receives the intermediate frequency output from the modem 20 and up-converts the frequency to the Ka band (Ka-band) and the up-frequency converter 111 and the up-frequency converter 111 It includes a high-power amplification unit 112 to amplify the up-converted frequency at a high output using a double-balanced pHEMT MMIC to transmit to the antenna (1).

The up-frequency converter 111 up-converts the intermediate frequency to the Ka band, and has a signal level amplification and output level adjustment function. The uplink frequency converter 111 includes a frequency synthesizer 111a that generates a local signal required for frequency conversion, and an intermediate frequency signal and a frequency synthesizer 111a output from the transmitter 21 of the modem 20. It includes a frequency converter 111b for synthesizing a local signal of) to generate a signal in the Ka band.

For example, the frequency synthesizer 111a generates a signal necessary for Ka-band frequency conversion using a 10MHz reference signal and a PLL (Phase Lock Loop), and then a micro-strip low-pass filter (micro-strip LPF). After removing the harmonics through), input to the mixer of the frequency converter 111b. The frequency converter 111b synthesizes the intermediate frequency signal and the local frequency signal of the frequency synthesizer 111a to generate and output a signal in the Ka band.

The high power amplifier 112 includes a high power amplifier (PA), a drive amplifier (DA), a low band filter (LPF), and a circulator.

High power amplifier (PA) can be used only in series structure, so it has low availability and linearity, and instead of the typical TWTA (Traviling Wave Tube Amplifier) structure, which has a high power consumption and large structure, it has a parallel structure, pHEMT (pseudomorphic High), which has the advantage of small and light weight. SSPA (Solid-State Power Amplifier) using Electron Mobility Transistor (MMIC) monolithic microwave integrated circuit is applied.

The drive amplifier DA is installed in front of the element of the high power amplifier PA to ensure linearity. For example, a drive amplifier with low power and high gain (18dB) characteristics is used.

The low-pass filter (LPF) is installed at the rear end of the high-power amplifier (PA), to meet the specifications of MIL-STD-188-164A voltage standing wave ratio (VSWR), suppression of unwanted and harmonic distortion, and output flatness. PBG (Photonic Band-Gap) structured harmonic LPF is used.

6 is a block diagram illustrating a receiver according to the present invention.

1 and 6, the receiving unit 12 according to the present invention converts the Ka band signal received from the antenna 1 into low noise amplification and down-frequency conversion and outputs it to the modem 20.

The receiving unit 12 tunes a radio frequency receiver (Tuned Radio Frequency, TRF) 121 that receives the Ka band signal received from the antenna 1 and the Ka band signal received through the receiver 121 with low noise amplification and And a low noise block down coverter (LNB) 122 that outputs the modem 20 by down-converting the frequency.

The low-noise downlink frequency converter 122 performs low-noise amplification to the Ka band signal received by the tuned radio frequency receiver 121, and a low-noise amplification section 122a and a low-noise amplification section 122a to receive the Ka-band signal at an intermediate frequency. The frequency converter 122b for down-converting to (intermediate frequency, IF) and the frequency converter 122b generate signals necessary for frequency conversion of the Ka band, and the frequency generated using the frequency doubler And a frequency synthesizing unit 122c that generates a local frequency signal corresponding to twice.

The frequency synthesizer 122c generates a 10 MHz reference signal using a rubidium clock having high stability and low phase noise, for example, and generates a signal necessary for frequency conversion using a PLL, and then uses a frequency doubler to localize it. Generate a frequency signal.

The main target design specification of the transmitting and receiving unit 10 according to the present invention is designed as shown in [Table 2] in consideration of MIL-STD-165A.

Parameter Target Designed Frequency Ka-band Transmission output 4W or more 5W Receive gain 60dB or more 63dB Reception noise figure 1.9dB or less 1.6dB Unnecessary 60dB or less Phase noise -65dBc ＠ 100Hz
-75dBc ＠ 1kHz
-85dBc ＠ 10kHz
-95dBc ＠ 100kHz
-95dBc ＠ 1MHz

As shown in FIG. 1, the modem 20 is, for example, equipment for receiving packet data through an Ethernet port and demodulating and transmitting according to a channel condition, and includes a transmitter 21 and a receiver 22.

7 is a block diagram illustrating a configuration of a transmitter according to the present invention.

1 and 7, the transmitter 21 receives a transmission signal in block units and encodes it using a Turbo Product Code (TPC), which is one of forward error correction codes, and an encoding unit ( 211), a modulator 212 that modulates the transmitted signal, and a first filter unit 213 that matches the transmitted signal modulated by the modulator 212 using a Root Raised Cosine (RRC) filter, and CIC An up-sampling unit 214 for increasing the sampling frequency of the output signal of the first filter unit 213 using a (Cascaded Integrator Comb) filter, and an output signal of the up-sampling unit 214 and a NCO (Numerically Controlled Ocsillator) ( 215) by mixing the frequency provided from the first mixing unit 216 to convert to the intermediate frequency signal band, and converts the digital signal output from the first mixing unit 216 into an analog signal and outputs it to the transceiver unit 10 And a digital / analog (D / A) converter 217.

The encoding unit 211 uses the Turbo Product Code (TPC), which is one of Forward Error Correction Codes (FECs) (hereinafter referred to as FECs), to generate errors in the receiving unit of the other terminal in the transmission signal. Code the code for detection and calibration.

TPC has similar performance to LDPC (Low Density Parity Check) code used in the DVD-S2 standard, but has a structure that can flexibly change the code rate. Instead, the complexity is higher than that of LDPC, but the complexity problem caused by replacing FEC with TPC is reduced by using FPGA logic of Comtech AHA's TPC IC.

FEC is one of the channel coating methods. Channel coding is a method of detecting and correcting errors by converting a digital audio signal appropriately to a transmission path. In the case of a satellite channel, it detects an error and requests a retransmission to the transmitting side, and then receives it again Since the delay time increases, the received signal is used to simultaneously perform detection and calibration.

As described above, the encoding unit 211 in the present invention uses a TPC as one of the FECs.

TPC is easy to vary the block size, so it is easy to vary the code rate. In addition, if the coding rate is easily variable, the transmission rate is naturally also variable.

For reference, the coding rate means a ratio between two data, and the smaller the coding rate is, the better the detection and correction performance is in general, while the data transmission rate is lowered.

The method of varying the block size of the TPC will be briefly described as an example.

In the case of the LDPC code applied to the FEC in the related art, the TPC code can be up to 16k, while the block size is limited to about 64k and 16k, but there is an advantage of easy variability.

TPC supports two modes, and the variable range in each mode is as shown in [Table 3].

EXTENDED HAMMING PARITY ONLY N / A (4,3) (8,4) (8,7) (16,11) (16,15) (32,26) (32,31) (64,57) (64,63) (128,120) (128,127)

For example, if a 2-dimensional code block is configured as' (32,26) × (32,26) ', a' (1024,676) 'code is constructed, and a 3-dimensional code block is' ( 64,57) × (16,15) × (16,15) ', the' (16384,12825) 'code can be constructed. In addition, a shortened code configuration is possible. The coding rate can be varied by combining the three axes of the X-axis, Y-axis, and Z-axis, bits, and rows of the first plane of the 3D code.

For example, briefly explaining the variable method based on the code of '(32,26) × (32,26) = (1024,676)', which is a two-dimensional code block, first, '5' on the X axis and Y axis If you reduce it by '4', you can create the code '(32-5,26-5) × (32-4,26-4) = (27,21) × (28,22) = (756,462)'. And, if the bit is reduced by 6 bits, a code of '(756-6,462-6) = (750,456)' can be created.

As another example, based on the code of '(32,26) × (32,26) × (4,3) = (4096,2028)', which is a 3D code block, like the variable of a 2D code block, in the X axis, If it is reduced by '7' on the 6 'and Y axis,' (32-6,26-6) × (32-7,26-7) × (4,3) = (26,20) × (25,19 ) × (4,3) = (2560,1100) 'code. And, if the column of the first side is reduced by '2' in the 3D code block, the code (2600-40, 1140-40) = (2560,1100) 'can be created.

As described above, according to the present invention, as the coding unit 211 uses a TPC instead of the existing LDPC, the block size is easy to vary compared to the LDPC. Accordingly, it is relatively easy to change the coding rate, and if the coding rate is easy to change, the transmission rate is also easy to change.

As shown in FIG. 7, the modulator 212 converts the error-corrected transmission data, that is, digital data, into a signal in a good form to distinguish it from the receiver, and outputs it to the first filter unit 213.

The phase shift keying (PSK) method used in the modulator 212 can support up to Binary-PSK (BPSK), Quardrature-PSK (QPSK), 8PSK, and 16APSK.

For reference, Binary-PSK (BPSK) is a method of distinguishing digital data '1' and '0' by sending and receiving on the phase of the signal, and for example, 'Cos (wt + 0 °), Cos (wt + 180 °) 'is assigned to' 0 'and' 1 ', respectively, to transmit and receive. Quardrature-PSK (QPSK) is divided into four types of '00, 01, 11, and 10 'and can send 2 bits at a time.

The signal modulated by the modulator 212 is transmitted to the first filter unit 213. The first filter unit 213 is a matched filter, and is used to find out which part of the received signal is the original signal when the original signal is known. That is, the same filter used by the transmitting end is used so that the receiving end receives the signal without loss.

The first filter unit 213 uses, for example, a 128-tap (Rot Raised Cosine) filter for basic 8-time oversampling so that the filter characteristics passed by the transmitting end and the receiving end are excellent.

As shown in FIG. 7, the signal that has passed through the first filter unit 213 is transmitted to the up-sampling unit 213 to adjust the bandwidth.

The up-sampling unit 214 interpolates and, as shown in FIG. 7, samples the sampled at a faster sampling frequency than the signal to be transmitted, and then reproduces the sampled discontinuous signal as a continuous signal.

The up-sampling unit 214 uses, for example, a CIC (CascadedIntegrator Comb) filter to sample a signal passing through the filter unit 213 at a sampling frequency faster than a signal to be transmitted, and then sampled discontinuous signals. To reproduce. At this time, the larger the difference between the frequency of sampling and the frequency of the original signal, the smaller the bandwidth of the signal.

The digital / analog converter 217 converts the up-sampled digital signal through the up-sampling unit 213 into an analog signal and transmits it to the transmitter 11 of the transceiver 10. In this case, the digital / analog converter 217 used, for example, a component satisfying a resolution of 14-bit and a spurious-free dynamic range (SFDR) of 80 dBc, and sampled with a 250 MHz clock.

8 is a block diagram illustrating a configuration of a transmitter according to the present invention.

1 and 8, the transmitter 22 receives the received signal received from the transceiver 10 and an analog / digital (A / D) converter 221 that converts the input analog signal to a digital signal. , A second mixing unit 223 for mixing the frequency of the NCO (Numerically Controlled Ocsillator) 222 to the signal output from the analog / digital converter 221 to lower the signal of the intermediate frequency band to a baseband signal, and A down-sampling unit 224 for reducing the sampling frequency of the signal output from the second mixing unit 223 using a Cascaded Integrator Comb (CIC) filter, and a down-sampling unit 224 using a Root Raised Cosine (RRC) filter The error included in the signal output from the second filter unit 225 to match the signal output from, and the demodulator 226 to demodulate the signal output from the second filter unit 225, demodulator) 226 And a decoding unit 227 that detects and corrects an error using a TPC.

The second mixing unit 223 outputs the signal received from the analog / digital converter 221 by lowering the intermediate frequency IF to the baseband signal using the frequency generated by the NCO 222.

The signal processing between the modem 20 and the transceiver 10 is performed by increasing the frequency in the intermediate frequency (IF) band, and the signal processing in the modem 20 is performed by lowering the frequency in the base band to process the mixing unit 223 Through, the intermediate frequency is lowered to the baseband signal.

The down-sampling unit 224 uses the CIC filter used in the up-sampling unit 214 of the transmitter 21 to lower the frequency upstream from the up-sampling unit 214 of the transmitter 21 to the original signal.

The second filter unit 225 filters the signals output from the down-sampling unit 224 by using an RRC filter to filter signals in unnecessary bands.

The demodulator 226 demodulates the signal output from the second filter unit 225 as an original signal, and demodulates and outputs the signal modulated by the modulator 212 of the transmitter 21 as an original signal.

As shown in FIG. 8, the decoder 227 detects an error in a signal output from the demodulator 226 using a TPC and corrects it, and outputs the same as the encoder 211 of the transmitter 21.

9 to 11 are simulation results according to each TPC modulation method (BPSK / QPSK, TPC 8PSK, TPC 16QAM) of a fly away terminal for satellite data communication using a TPC method according to an embodiment of the present invention, and fly among various coding rates The performance of BER (Bit Error Rate) at five code rates '0.324, 0.444, 0.611, 0.75, 0.876' used in the design of the away terminal was simulated using a performance analysis tool provided by TPC IC manufacturers.

12 is a diagram showing a test configuration for measuring the performance of a flyaway terminal for satellite data communication using a TPC method according to an embodiment of the present invention, as shown in FIG. 12, a signal transmitted from 'Fly-away Terminal I' Received from 'Fly-away Terminal Ⅱ', measured performance using BER meter, and received from 'Fly-away Terminal Ⅱ', measured performance using BER meter Did.

13 is a view showing the measurement result of the transmit / receive antenna of the fly-away terminal for satellite data communication using the TPC method according to an embodiment of the present invention. As shown in FIG. 13, the transmit antenna gain is 45.7 dBi (a) and the receive antenna gain Was measured to be 42.0 dBi (b).

14 is a diagram showing the transmission output result of a flyaway terminal for satellite data communication using a TPC method according to an embodiment of the present invention, as shown in FIG. 14, measured to 4W (36.45dBm) or more, and eventually meets 4W or more specifications Was confirmed.

15 is a view showing a reception gain and a noise index measurement result of a flyaway terminal for satellite data communication using a TPC method according to an embodiment of the present invention. As shown in FIG. 15, the reception gain satisfies a specification of 60 dB or more in an operating frequency band. The results were confirmed, and it was confirmed that the noise index specification in the operating frequency band satisfies 1.6 dB or less.

FIG. 16 is a diagram showing transmission / reception unwanted wave measurement results of a flyaway terminal for satellite data communication using a TPC method according to an embodiment of the present invention. As shown in FIG. 16, it was confirmed that the specification satisfies 60 dBc or less.

FIG. 17 is a diagram showing the results of measurement of transmit / receive phase noise of a fly away terminal for satellite data communication using a TPC method according to an embodiment of the present invention, and as shown in FIG. 17, it was confirmed that the specification was satisfied.

18 and 19 are results of measuring the modem unit performance of a fly away terminal for satellite data communication using a TPC method according to an embodiment of the present invention through a PTP BER test, and it is difficult to adjust and measure a channel environment and a signal-to-noise ratio (SNR). The results of measuring the error-free (BER 10-7 or less) signal-to-noise ratio while varying in units of 1 dB are shown in FIGS. 9 and 10.

In the flyaway terminal for satellite data communication using the TPC method according to an embodiment of the present invention, the weight of the main / sub reflector is made of magnesium to minimize the weight for miniaturization and weight reduction. In addition, the modem unit was designed by applying TPC instead of LDPC code to increase the variability of traffic section in DVB-S2 based design, and by using AHA IC to solve the complexity problem, the actual implementation logic amount was saved. A CIC filter that can support up to 512 interpolation rates was applied to select various bandwidths.

Overall, the flyaway terminal for satellite data communication using the TPC method according to the embodiment has been designed with priority on the variability of bandwidth and transmission rate, and as a result of the test, the performance is about 2 ~ 3dB lower than the simulated TPC codec performance based on Eb / No. I could confirm. As shown in [Table 4], it can be confirmed that the target specification was exceeded through the test results.

Parameter Target Designed Frequency Ka-band Antenna Gain Tx 44.0dBi 45.7dBi Rx 41.5dBi 42.0dBi Transmission output 4W or more 5W Receive gain 60dB or more 60.5dB Reception noise figure 1.9dB or less 1.49dB Unnecessary 60dBc or less            67.05dBc Phase noise -65dBc ＠ 100Hz
-75dBc ＠ 1kHz
-85dBc ＠ 10kHz
-95dBc ＠ 100kHz
-95dBc ＠ 1MHz -66.64dBc ＠ 100Hz
-81.42dBc ＠ 1kHz
-93.57dBc ＠ 10kHz
-97.57dBc ＠ 100kHz
-103.24dBc ＠ 1MHz Modulation and demodulation method QPSK, 8PSK, 16APSK
FEC Turbo Product Code (TPC) Maximum transmission speed 2Mbps Multiple access method DAMA MF-TDMA

In the above, although preferred embodiments of the present invention have been described and illustrated using specific terms, such terms are only intended to clearly describe the present invention, and embodiments and described terms of the present invention are the technical spirit of the following claims. And it is obvious that various changes and changes can be made without deviating from the scope. Such modified embodiments should not be understood individually from the spirit and scope of the present invention and should be said to fall within the scope of the claims of the present invention.

1: antenna 1a, 1b: reflector
1c: Feeding horn 1d: Pleated polarizer
1e: orthogonal mode converter 10: transceiver
11: transmitter 111: up-frequency converter
111a: frequency synthesizer 111b: frequency converter
112: high-power amplifier 12: receiver
121: tuned radio frequency receiver 122: low-noise down-frequency converter
122a: low-noise amplification section 122b: frequency conversion section
122c: frequency synthesis section 20: modem
21: transmitting unit 211: coding unit
212: modulation unit 213, 225: filter unit
214: upsampling unit (interpolation) 215, 222: NCO
216, 223: mixing unit 217: digital / analog converter
22: receiver 221: analog / digital converter
224: down-sampling unit 226: demodulation unit
227: decoding unit

Claims (10)

An encoding unit that receives a transmission signal in block units and encodes it using a Turbo Product Code (TPC), one of forward error correction codes;
A modulator for modulating a transmission signal encoded by the encoder;
A first filter unit that matches the transmitted signal modulated by the modulation unit using a Root Raised Cosine (RRC) filter;
An up-sampling unit that increases a sampling frequency of an output signal of the first filter unit by using a CIC (Cascaded Integrator Comb) filter;
A first mixing unit mixing the output signal of the up-sampling unit and a frequency provided from a NCO (Numerically Controlled Ocsillator) and converting it into an intermediate frequency signal band; And
Includes a digital / analog (D / A) converter for converting the digital signal output from the first mixing unit to an analog signal and outputting it to a transmitting and receiving unit connected to an antenna for communicating with a satellite.
The antenna separates a high-gain, small-volume, dual-offset gregorian type reflector, a corrugated type feed horn, a pleated polarizer for generating circular polarization, and a transmit / receive signal. Modem for a fly away terminal for satellite data communication, including an orthomode transducer (OMT).
An analog / digital converter that converts a signal in the Ka band received from an antenna communicating with a satellite into a digital signal by receiving a received signal from a transceiver that converts low-noise amplification and down-frequency;
A second mixing unit which converts a signal in the intermediate frequency band into a baseband signal by mixing frequencies of NCO (Numerically Controlled Ocsillator) with a signal output from the analog / digital converter;
A down-sampling unit that lowers the sampling frequency of the signal output from the second mixing unit using a cascaded integral filter (CIC) filter;
A second filter unit that matches the signal output from the down-sampling unit using a Root Raised Cosine (RRC) filter;
A demodulator demodulating the signal output from the second filter unit; And
Includes a decoding unit that detects and corrects an error included in the signal output from the demodulator using a Turbo Product Code (TPC).
The antenna separates a high-gain, small-volume, dual-offset gregorian type reflector, a corrugated type feed horn, a pleated polarizer for generating circular polarization, and a transmit / receive signal. Modem for a fly away terminal for satellite data communication, including an orthomode transducer (OMT).
An encoding unit that receives a transmission signal in units of blocks and encodes it using a Turbo Product Code (TPC), one of forward error correction codes, and a modulation unit that modulates the transmission signal encoded by the encoding unit, and modulates the modulation unit A first filter unit that matches the transmitted signal using a Root Raised Cosine (RRC) filter, and an up-sampling unit that increases the sampling frequency of the output signal of the first filter unit using a Cascaded Integrator Comb (CIC) filter. A first mixing unit for mixing the output signal of the up-sampling unit and a frequency provided from a NCO (Numerically Controlled Ocsillator) and converting it into an intermediate frequency signal band, and a satellite by converting the digital signal output from the first mixing unit into an analog signal A transmission unit including a digital / analog (D / A) converter that outputs to a transmission / reception unit that transmits to an antenna communicating with the antenna; And
An analog / digital converter that converts the received signal from the transceiver to a digital signal, and the frequency of NCO (Numerically Controlled Ocsillator) mixed with the signal output from the analog / digital converter to convert the signal in the middle frequency band into a baseband signal. A second mixing unit to convert, a down-sampling unit to lower the sampling frequency using a CIC (Cascaded Integrator Comb) filter, and the down-sampling using a RRC (Root Raised Cosine) filter A second filter unit that matches the signal output from the unit, a demodulator that demodulates the signal output from the second filter unit, and an error included in the signal output from the demodulator using TPC (Turbo Product Code) Includes; receiving unit including a decoding unit for detecting and correcting errors by,
The antenna separates a high-gain, small-volume, dual-offset gregorian type reflector, a corrugated type feed horn, a pleated polarizer for generating circular polarization, and a transmit / receive signal. Modem for a fly away terminal for satellite data communication, including an orthomode transducer (OMT).
The method according to any one of claims 1 to 3,
The transmitting and receiving unit receives a signal in the intermediate frequency band from the modem, converts it to the Ka band, and transmits it to the antenna through high-power amplification using a double balanced structure of pseudomorphic High Electron Mobility Transistor (pHEM) monolithic microwave integrated circuit (MMIC) Modem for a fly away terminal for satellite data communication.
delete The method according to any one of claims 1 to 3,
The reflector is a flyaway terminal modem for satellite data communication made of magnesium.
The method according to any one of claims 1 to 3,
The transmitting and receiving unit,
An up-frequency converter that receives an intermediate frequency output from the modem and up-converts the frequency to a Ka-band; And
A high-power amplifying unit that amplifies and transmits the frequency up-converted by the up-frequency converter to a high power using a dual equilibrium structure, pHEMT (Pseudomorphic High Electron Mobility Transistor) MMIC (Monolithic Microwave Integrated Circuit);
Modem for a fly away terminal for satellite data communication that includes.
The method of claim 7,
The uplink frequency conversion unit,
A frequency synthesizer generating a local signal necessary for frequency conversion;
A frequency converter configured to generate a Ka band signal by synthesizing the intermediate frequency signal output from the modem and the local signal of the frequency synthesizer;
Modem for a fly away terminal for satellite data communication that includes.
The method according to any one of claims 1 to 3,
The transmitting and receiving unit,
A tuned radio frequency receiver (TRF) for receiving the Ka band signal received from the antenna; And
A low noise block down coverter (LNB) that amplifies and down-converts the Ka band signal received through the tuned radio frequency receiver and outputs it to the modem;
Modem for a fly away terminal for satellite data communication that includes.
The method of claim 9,
The low-noise downlink frequency converter,
A low-noise amplifying unit for amplifying the low-noise signal of the Ka band received by the tuned radio frequency receiver;
A frequency converter that down-converts the Ka band signal received through the low-noise amplifier to an intermediate frequency; And
A frequency synthesizer generating a signal necessary for frequency conversion of the Ka band in the frequency converter and generating a local frequency signal corresponding to twice the frequency generated using a frequency doubler;
Modem for a fly away terminal for satellite data communication that includes.

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