• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.1104-1111
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• 2003

The paper presents an algorithm for the compensation of gain and phase imbalances to exist between I-phase and Q-phase signal at direct conversion receiver. We propose a gain and phase imbalances blind equalization compensation algorithm by using variable step-size adaptive loop at direct conversion receiver. The blind equalization schemes have trade-off between convergence speed and jitter effect for the compensation of gain and phase imbalance. We propose the variable step-size adaptive loop method, which varies the loop coefficients according to errors, for recovering these problem. By using variable step-size adaptive loops, we propose to speed up the convergence process and reduce the jitter effect and simulation results show that the algorithm compensates signal loss and speeds up convergence time.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.7
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• pp.761-768
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• 2010

This paper presents an effective method to achieve the wideband waveform for high resolution SAR(Synthetic Aperture Radar) using the frequency multiplication technique. And also this paper analyzes the root causes for the spectral regrowth due to 3rd-order intermodulation in chirp bandwidth expansion scheme using quadrature modulator and frequency multipliers. The amplitude and phase imbalance requirement are defined based on the simulation results in terms of quadrature channel imbalance. This minimizes the degradation of range resolution, peak sidelobe ratio and integrated sidelobe ratio. The wideband chirp generator using the frequency multiplier and memory map scheme was manufactured and the compensation technique was presented to reduce the spectral regrowth of SAR waveform by minimizing the amplitude and phase imbalance. After I and Q channel imbalance adjustment, the carrier level reduces －28.7 dBm to －53.4 dBm. Chirp signal with 150 MHz bandwidth at S-band expands to 600 MHz bandwidth at X-band. The sidelobe levels are reduced by about 8 to 9 dB by compensating the amplitude balance between I and Q channels.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.6 s.324
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• pp.1-7
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• 2004

The development of direct receiver techniques is expected to be a solution for future wideband or multi-band wireless systems based on software defined radio. In this Paper, we study the regeneration of I and Q signals for the SDR based direct conversion receiver, so that we can handle a wide bandwidth and maintain maximal flexibility in system utilization. After modeling the basic system considering the real wireless communication environment, and studying the impact of imperfect phase imbalance on the performance of a direct conversion receiver, we propose a suboptimal I and Q signal regeneration algorithm for the system. The proposed algerian regenerates I and Q signals using a real time early-late compensator which effectively estimates phase imbalances and gives feedback in a directreceiver. The proposed algorithm is shown to mitigate the impact of AWGN and improves performance especially at low SNR channel condition. According to the computer simulation, the BER performance of the proposed system is at least about 4 dB better than conventional systems under $45{\~}55$ degrees random phase errors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11A
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• pp.933-940
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• 2011

In this paper, Ka-band transceiver for road watch radar system is designed and fabricated. The transceiver for road watch radar system is composed of waveform generator, frequency generator. IF transceiver and RF up/down converter. The transceiver especially has 3 different waveform mode for target detection range. The transceiver had over 150 MHz bandwidth in Ka-band and 22 dBm output power. The receiver gain and noise figure was 30 dB and 4 dB respectively. The receive dynamic range was 65.28dB and amplitude imbalance and phase imbalance of I/Q channel was 0.3 dB and 1.8 degree respectively. The transceiver meets the required electrical performances through the individual tests.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.517-520
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• 2000

This paper deals with the statistical analysis of an autocalibration procedure for the gain and phase imbalances between the in-phase (I) and quadrature (Q) components in quadrature receivers. In real implementation, the imbalances of the gain and phase exist and degrade the performance of the receiver. In this paper we investigate the statistical characteristic of the estimates in an on-line imbalance estimation method for the receiver under the assumption of an additive white Gaussian noise environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2165-2170
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• 1997

In this paepr, the distortion effects of impairments in CDMA transmitter system were analyzed. We considered not only linear distortion effects, for example, I/Q imbalance, quadrature offset and carrier leakage, but also nonlinear distortion effects such as AM-AM and AM-PM noise in power amplifier. To investigate how the impariments impact on the performance of CDMA transmitter, all effects represented as a function of CDMA modulation quality which is an important measure of the transmitted signal. These results show the limitation value of each impairment which is required to satisfy the IS-95 standard.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.4
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• pp.76-85
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• 2008

In this paper, a 800 MHz 1 W cartesian feedback linearized power amplifier is designed and fabricated for TETRA handset application. For amplification of TETRA signal with 200 kHz narrow bandwidth, amplifier linearization performance of more than 30 dBc is improved through the cartesian feedback linearizer at the offset Sequency of ${\pm}25$ kHz. It is clear that the linearization performance is affected by imbalance of gain and phase between I/Q signals and also DC offset. The linearization performance can be maximized by the compensation of those influences. Cartesian feedback is suitable for a liearization technique of narrow band signal with QAM and another modulation signals, as well.

• ETRI Journal
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• v.26 no.5
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• pp.501-504
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• 2004

This paper presents a simple gain/phase blind compensation algorithm with an automatic gain control (AGC) function for the adoption of the AGC function and compensation for gain/phase imbalances in quadrature phase shift keying (QPSK) direct conversion receivers (DCRs). The AGC function is interactively operated with the compensation algorithm for gain/phase imbalances. By detecting the gain sum and difference values between the I-channel and Q-channel, the combined AGC and gain imbalance compensation algorithm provides a simpler DCR architecture.

• Journal of Genetic Medicine
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• v.7 no.1
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• pp.82-86
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• 2010

Jumping translocations (JT) are chromosomal rearrangements involving one donor chromosome and several recipient chromosomes. While JTs are frequently observed as acquired chromosomal abnormalities in hematologic malignancies, constitutional JTs are only rarely reported. We report two cases of constitutional JT in chorionic villi derived from the products of conception. The karyotype of the first case was 46,XY,add(18)(p11.1)[61]/45,XY,der(18;21)(q10;q10)[32]/46,XY,-18,+mar[16]/46,XY,i(18)(q10)[9]/45,XY,der(15;18)(q10;q10)[6]/46,XY,+1,dic(1;18)(p22;p11.1)[2]/45,XY,der(13;18)(q10;q10)[1]/46,XY[32]. The donor was a chromosome 18. The recipient chromosomes were chromosomes 1, 13, 15, 18 and 21. In the second case, the karyotype was 46,XY,der(22)t(9;22)(q12;q13)[22]/46,XY,der(22)t(1;22)(q21;q13)[13]/46,XY,add(22)(q13)[5]/46 XY[23]. The donor was a chromosome 22 and recipients were chromosomes 1 and 9. Both cases were de novo. The breakpoints of chromosomes were mostly in centromeric regions, pericentromeric regions, or telomeric regions. Normal cell lines were observed in both cases. This report supports the prior findings that the unstable nature of JT, resulting in chromosomal imbalance, most likely contributed to these early miscarriages.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.573-582
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• 2010

In this paper, X-band transceiver for high resolution wideband SAR systems is designed and fabricated. Also as a technique for enhancing the performance, error compensation algorithm is presented. The transceiver for SAR system is composed of transmitter, receiver, switch matrix and frequency generator. The receiver especially has 2 channel mono-pulse structure for ground moving target indication. The transceiver is able to provide the deramping signal for high resolution mode and select the receive bandwidth for receiving according to the operation mode. The transceiver had over 300 MHz bandwidth in X-band and 13.3 dBm output power which is appropriate to drive the T/R module. The receiver gain and noise figure was 39 dB and 3.96 dB respectively. The receive dynamic range was 30 dB and amplitude imbalance and phase imbalance of I/Q channel was ${\pm}$0.38 dBm and ${\pm}$3.47 degree respectively. The transceiver meets the required electrical performances through the individual tests. This paper shows the pulse error term depending on SAR performance was analyzed and range IRF was enhanced by applying the compensation technique.