• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.505-511
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• 2003

In this paper, a driving amplifier stage with 1 Watt output has been designed and fabricated, which is operating at UHF band( 470 ∼ 806 MHz) for digital TV repeater. In the driving amplifier stage, preamplifier and 1 Watt unit amplifier are integrated by one electric substrate which is 2.53 in dielectric constant and 0.8 mm thickness. When the driving amplifier stage is flown by bias voltage of 28 V DC and current of 900 mA. it has the gain of more than 53.5 dB. the gain flatness of $\pm$0.5 dB and return loss of less than -15 dB in 470 ∼ 806 MHz. Also, when two signals at 2 MHz frequency interval are input port into the driving amplifier stage with 1 Watt output, it resulted in excellent characteristics to designed specification with showing intermodulation distortion characteristics of more than 48 dBc.

• ETRI Journal
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• v.33 no.5
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• pp.670-678
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• 2011

This paper investigates the design and performance of a digital on-channel repeater (DOCR) for use in Advanced Television Systems Committee (ATSC) digital television (DTV) broadcasting. The main drawback of a DOCR is the echo interference caused by coupling between transmitter and receiver antennas, which induces system instability and performance degradation. In order to overcome this problem, an echo canceller based on the adaptive echo channel estimation (ECE) technique has been researched and applied for a DOCR. However, in the case of ATSC, the pilot signal, which is used for carrier synchronization, may cause a DC offset error and reduce the isolation performance of the echo canceller for a DOCR in an ATSC network. Moreover, since the multipath fading effect of a radio channel usually occurs in a real environment, it should be minimized to improve the overall performance of a DOCR. Therefore, due to the limited isolation performance of echo canceller and the multipath fading effect, an interference cancellation system (ICS) is proposed for a DOCR in an ATSC network. The performance of the proposed DOCR with an ICS is evaluated by software simulation and hardware test results.

• Journal of Navigation and Port Research
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• v.26 no.2
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• pp.215-220
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• 2002

In this paper, the 100 watt unit ower amplifier using temperature independent biasing for DTV (Digital Television) repeater application is designed and fabricated. The DC operation point of this unit power amplifier at temperature variation from $20^{\circ}C$ to $100^{\circ}C$ is fixed by active bias circuit. The variation of current consumption in the 100 watt unit power amplifier has an excellent characteristics of less than 0.6A. The implemented unit power amplifier has the gain over 12dB, the gain flatness of less than 0.5dB and input and output return, loss of than 15dB over the DTV repeater frequency range (470~806MHz). This unit power amplifier yields intermodulation distortion(IMD) of more than 32dBc at 2MHz offset, which satisfies the IMD at output power of 100 watt (50dBm).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7A
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• pp.725-733
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• 2006

In this paper, we propose an algorithm which makes the frequency of output signal synchronize with frequency of input signal in Equalization Digital On-channel Repeater (EDOCR) system which was proposed to overcome the disadvantage of conventional Digital On-Channel Repeater (DOCR). Also, we verify the algorithm by using the mathematical equivalent model and analysis the performance by implying the algorithm to EDOCR. The main idea is to use the frequency offset information, which comes from carrier recovery in the receiving part of EDOCR, when the demodulated symbol is re-modulated in transmitting part. Based on the proposed algorithm, EDOCR not only makes the output signal synchronized with input signal in frequency but also emit the output signal which satisfies the ATSC transmission standard without additional equipments such as Global Positioning System (GSP).

• Journal of Broadcast Engineering
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• v.14 no.3
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• pp.311-321
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• 2009

In a single frequency network (SFN) for Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) system, the interference due to the use of same frequency among multiple transmitters or repeaters is inevitable for receivers. This problem can be solved by adjusting transmit power and time of each transmitter and repeater. To adjust SFNs, the ATSC recommended practice (RP) introduces a transmitter identification (TxID) signal which is embedded in a signal from each transmitter or repeater. This paper proposes an efficient method to estimate the individual reception power from each transmitter or repeater based on the channel profile of SFN and the total reception power. Moreover, field test results are provided to evaluate the performance of the proposed method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.737-740
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• 2003

SFN (Single Frequency Network) and OCR (On Channel Repeater) are often considered for the efficiency of frequency allotment in digital TV. In this paper, we discuss the performance and evaluate some coverage criterions for SFN and OCR. Also, we propose MATLAB simulator for coverage planning and estimation.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.77-80
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• 2005

본 논문에서는 ATSC 지상파 디지털 TV 방송방식을 사용하는 등화형 동일채널 중계기(Equalization Digital On-Channel Repeater: EDOCR)에서의 신호처리 시간지연을 최소화하기 위한 전치등화 방법에 대하여 기술하고 결과를 다양한 각도에서 분석한다. 제안된 전치등화 방법은 기준신호인 기저대역 신호와 복조된 중계기 출력신호를 이용하여 전치등화필터계수를 계산하고 펄스성형필터계수와의 컨볼루션을 통해 얻어진 새로운 펄스성형필터를 이용하는 것이다. 새로운 펄스성형필터의 전치 탭 수를 조절함으로써 시간지연을 최소화하고, 마스크필터에 의한 선형왜곡을 보상할 뿐 아니라, 원래 펄스성형필터의 대역 외 방사 특성의 열화를 최소화할 수 있다. 이를 컴퓨터 시뮬레이션 및 제작된 전치등화기를 이용하여 검증하였다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.8
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• pp.99-107
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• 2010

In a single frequency network (SFN) for Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) system, the interferences induced by the multiple transmitters and/or repeaters using the same frequency are inevitable. Since the presence of interferences results in performance degradation of the SFN, it is crucial to manipulate the interferences by adjusting the transmit power and timing of each transmitter and repeater. In the ATSC terrestrial DTV system, in order to facilitate the interference manipulation process, a transmitter identification (TxID) signal which is uniquely embedded in the signal to be transmitted from each transmitter and repeater is recommended. Even though the injection level of the TxID signal is much lower than the DTV signal, the TxID signal injection infects the DTV signal. Hence, the effect of the TxID signal on the DTV signal must be investigated before deployment. In this paper, the effect of the TxID signal on the performance of legacy DTV receivers under additive white Gaussian noise and multipath channel environments is investigated not only with computer simulation but also with laboratory and field tests. The test results show that the average threshold of visibility degradation of the legacy DTV receivers due to the TxID signal injection is less than 0.2 dB at the TxID injection level of -30 dB.

• Journal of Broadcast Engineering
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• v.7 no.1
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• pp.10-20
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• 2002

In order to fill the gaps in DTV coverage, KBS Technical Research Institute has researched on DTV on-channel repeating systems as well as DTV translators. The on-channel repeater can reuse frequency resources for expanding service coverage. but it has also many restricts in applications for ATSC DTV system. Thiss Paper compares two kinds of DTV on-channel repealer systems and also presents field test results of both systems. From these results, we Infer their characteristics and summarize the conditions and possibilities of the application for our broadcasting networks.

• Journal of Navigation and Port Research
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• v.26 no.3
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• pp.289-294
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• 2002

The broadband high power 3-way combiner was designed and fabricated for the digital TV repeater. To achieve increase of the bandwidth and the high power capability, Wilkinson type power divider was adopted in our research. First of all, Wilkinson type power divider of equal-split and unequal-split were combined, and the characteristics of the four port in-phase power combiner was simulated for each thickness of dielectric substrates. As the results of simulation, the power combiner fabricated by using dielectric substrate of 120 mil-thickness has the characteristics as follows: insertion loss of less than -651 dB, reflection coefficient of less than -13 dB, isolation among the output ports of less than -15 dB, and pose difference among the output ports of smiler than 13$^{\circ}$. Therefore, this power combiner was possible to improve the limit of microstrip line width due to high impedance, the problem of power loss due to interaction between strip lines in a high power combiner and narrow bandwidth simultaneously. Furthermore, making broadband and high power could be achieved since the fabricated 3-way combiner has good characteristics of insertion loss, the reflection coefficient, separation between ports, and phase difference.