• Proceedings of the KIEE Conference
• /
• 2002.11c
• /
• pp.301-304
• /
• 2002

This paper has been studied an A/D conversion system for precision weighing signal process In weighing system. A/D conversion has some problem.; offset drift voltage with environment situation and nonzero value of initial output voltage. The Offset voltage in analog circuit produces a drift of an output voltage before A/D conversion stage. This paper suggested the method of reducing the offset voltage by switching analog chopping circuit and making the initial output close to zero to enhance the swing range by D/A converter. Also, we have designed active filter and digital filter with Auto Zero Tracking algorithm for better signal process of the weighing system.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.8
• /
• pp.69-75
• /
• 1998

We demonstrate wavelength conversion of 2.5Gb/s optical signals by four-wave mixing (FWM) in a semiconductor optical amplifier (SOA). We investigate the effect of input pump and signal powers on the coversion efficiency, optical signal-to-noise ratio (OSNR) and extinction ratio to be a measure of performance in a wavelength converter. As a result, we show that the maximum bit error rate (BER) performance can be obtained by co promising among high-vonversion efficiency (minimum Pprobe), high-OSNR (maximum Pprobe) and low-cross-gain saturation effects (Pprobe kept at least 6dB weaker than Ppump). In our experiment, we obtain optimum performance at +3 dBm pump power and -6dBm signal power. The power penalty incurred in the wavelength conversion can be minimized by careful selection of the input pump and signal powers. We show that about 0.5dB power penalty for 3.2nm wavelength coversion at 10-10 BER is achievable.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.6
• /
• pp.67-76
• /
• 1997

In radar signal processing, an A/D converter with sufficient dynamic range and high sampling speed is required to detect the weakest target signals in heavy clutter and ECM environments. As the sampling frequency increases, the amount of digital data transfered to the signal processing module is also increased. To overcome these massive data transfer burden, we need an A/D conversion module with an enough data transfer rate. In this paper, we proposed an implementation scheme of a new A/D conversio module that can be used in multi-mode 3-D phased array radar signal processing system, and evaluated the performance. The proposed A/D conversion module is implemented with a standard A/D converter and a 6U-standard VME bus.

• Journal of the Institute of Convergence Signal Processing
• /
• v.1 no.2
• /
• pp.131-137
• /
• 2000

In this paper, as a compatible software radio transmission system, Digital-Radio conversion system which can directly change the digital signal generated by the logic circuit into radio signal is proposed. By the vector synthesis method, the digital signals can change directly into radio signal. If such a circuit is realized, RF circuit and an antenna can be composed by the simple one device, and the radio is directly controlled and performed by the software processing which is the essence of software radio. This Digital-Radio conversion system of this paper give many number of communication channels being offered by PN code and offer a hardware design flexibility by digitization, therefore it decrease the percentage ratio of hardware of system and give a more flexible function of software basis. In this paper, the principle of digital to radio signal generation algorithm is explained and the performance characteristics of proposed algorithm is shown in time base by the computer simulation method.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.718-721
• /
• 2003

It is often desirable that manufacturers and users can convert the reference white of display into the preferred color temperature by controlling the color temperature that is one of representative color characteristics of a light source. Accordingly, this paper proposes an efficient method of color compensation for displaying the uncalibrated video signal in PDP-TV and is also shown to be successfully coupled with flexible color temperature conversion based on the signal processing technique.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.1 no.1
• /
• pp.23-31
• /
• 1976

When Television signal of VHF and UHF channel is retransmitted at the relay system with 6MHz Bandwidth including video and aural signals, the image is often affected with the unnatural changes of output amplitude frequency response within ttle region of dual sideband near to the carrier frequency. These phenomena are caused by the unnecessary lower sideband due to the spurious emission at the local oscillator, the nonlinear distortion in the linear amplifier, the intermoudulation distortion with the components of neighboring signal, the AM-PM conversion, and the envelope delay distortion. From the output characteristics, considering above results, the chief cause is caused by nonlinear response and has an effect on the bias states. Finally, it is confirmed that the effects on neighboring signal appear high in case of Down conversion than Up conversion and obtained the method for reducing the effects on the system.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.8C
• /
• pp.806-815
• /
• 2006

It is studied to design a low pass filter of the SRC(sample rate converter), which is used to change the sampling rate of digital signals such as in digital modulation and demodulation systems. The larger the conversion ratio of the sample rate becomes, the more signal processing is needed for the filter, which corresponds to the more complexity in circuit realization. Thus it is important to reduce the amount of signal processing for the case of high conversion ratio. In this paper it is presented a design method of a two-stage cascaded FIR filter, which proved to have reduced amount of signal processing in comparison with a conventional single-stage one. The reduction effect of signal processing turned out to be more noticeable for larger value of conversion ratio, for instance, giving down to 72% in complexity for the conversion ratio of 32. It has been shown that the reduction effect is dependent to specific combination of conversion ratios of the cascaded filters. So an exhaustive search has been performed in order to obtain the optimal combination for various values of the total conversion ratio. In this paper every filter is considered to be implemented in the form of a polyphase FIR filter, and its coefficients are determined by use of the Parks-McCllelan algorithm.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.2
• /
• pp.18-26
• /
• 2015

In this paper, we studied the method for analyzing and estimating the parameters that induce I/Q imbalance in the repeater using direct conversion RF. In repeater, amplitude, phase, and filter mismatch are generated in the receiving-end which converts RF signal to baseband signal. And amplitude and phase mismatch are generated in the transmitting-end which converts baseband signal to RF signal. Accordingly, we modeled the parameters that cause I/Q imbalance in the structure of the repeater in order, and proposed a feedback test structure from the transmitting-end to the receiving-end for estimating the corresponding parameters. By comparing the test transmitting signal and received signal, it is possible to estimate the I/Q imbalance parameters which occurred from mixed components of real and imaginary part. And it was confirmed that I/Q imbalance phenomenon has been properly compensated with estimated parameters at the direct conversion RF repeater.

• Journal of IKEEE
• /
• v.3 no.1 s.4
• /
• pp.69-78
• /
• 1999

In this paper, direct conversion receiver was designed to even harmonic anti-paralled diode pair ring mixer. Using a second harmonic component of LO instead of LO signal and RF signal are mixed by SHP(Sub Harmonic Pumped) mixer with anti-parallel diode pair. Canceling the harmonics of LO signal in ring mixer, SHP mixer using anti-parallel diode pair could mostly reduce the radiation of LO signal through a input port the most, good isolation characteristic, and low spurious characteristic by LO signal was shown over broad band. The produced SHP mixer showed LO/IF, RF/IF and LO/RF isolation was 24.6dB,36.2dB and 22.5dB respectively. And conversion loss was measured 15.6dB, IF output -35.6dBm with -20dBm RF input and 5.5dBm LO signal. 1dB compression point of If signal, in respect to RF signal, was found at the 0dbm RF signal.

• Journal of Positioning, Navigation, and Timing
• /
• v.10 no.1
• /
• pp.1-12
• /
• 2021

Due to the Global Navigation Satellite System (GNSS) modernization, the recently launched GNSS satellites transmit signals at various frequency bands of L1, L2 and L5. Considering the Korea Positioning System (KPS) signal and other GNSS augmentation signals in the future, there is a high probability of applying more complex communication techniques to the new GNSS signals. For the reason, GNSS receivers based on flexible Software Defined Radio (SDR) concept needs to be developed to evaluate various experimental communication techniques by accessing each signal processing module in detail. In this paper, we introduce a multi-constellation (GPS/Galileo/BeiDou) multi-band (L1/L2/L5) SDR by utilizing Ettus USRP N210. The signal reception module of the developed SDR includes down-conversion, analog-to-digital conversion, signal acquisition, and tracking. The down-conversion module is designed based on the super-heterodyne method fitted for MHz sampling. The signal acquisition module performs PRN code generation and FFT operation and the signal tracking module implements delay/phase/frequency locked loops only by software. In general, it is difficult to sample entire main lobe components of L5 band signals due to their higher chipping rate compared with L1 and L2 band signals. Experiment result shows that it is possible to acquire and track the under-sampled signals by the developed SDR.