Dong-Jin Yeom

Implementation of High-Resolution Angle Estimator for an Unmanned Ground Vehicle

We implemented a real-time radar system for an unmanned ground vehicle designed to run on unpaved or bumpy roads. The system must be able to detect slow targets in a cluttered environment and cover wide angular sections with high resolution at the same time. The system consists of array antennas, preprocessors for digital beam forming, and digital signal processors for the detection process which uses sawtooth waveforms and high-resolution estimation, and is called forward/backward spatial smoothing beamspace multiple signal classification (FBSS BS-MUSIC). We show that the sawtooth waveforms enhance the angular estimation capability of FBSS BSMUSIC in addition to their well-known advantages of removing the ambiguity of targets and detecting slow targets with improved velocity resolution.

A novel unambiguous composite binary offset carrier(6,1,1/11) tracking based on partial correlations

An unambiguous tracking scheme is proposed for CBOC(6,1,1/11) signal.The proposed scheme combines the partial correlations in a specially designed way.The autocorrelation side-peaks are completely removed by the proposed scheme.Better TESD and MEE performances are achieved over those of the conventional schemes. This paper proposes a novel unambiguous correlation function for composite binary offset carrier (CBOC) signal tracking based on partial correlations. In the proposed scheme, first, we partition sub-carriers of the CBOC signal into partial sub-carriers, and subsequently, we obtain partial correlations by correlating the partial sub-carriers with the received CBOC signal. Finally, a novel unambiguous correlation function with no side-peak is constructed by combining the partial correlations in a specially designed way. Unlike the conventional schemes, the proposed scheme does not require any auxiliary signal and from numerical results, it is found to offer a better tracking performance than those of the conventional schemes in terms of the tracking error standard deviation (TESD) and multipath error envelope (MEE).

A Novel Repeat-back Jamming Detection Scheme for GNSS using a Combined Pseudo Random Noise Signal

A repeat-back jamming signal is an intentionally re-broadcasted GNSS (Global Navigation Satellite System) interference. In this paper, a novel repeat-back jamming detection scheme is proposed. The proposed scheme uses a combined pseudo random noise signal (C-PRN) and is available for a generic GNSS receiver with a single antenna. The C-PRN signal is made by combining several received pseudo random noise signals that had been transmitted from the visible GNSS satellites. Through a Monte-Carlo simulation, the detection probability of a repeat-back jamming signal detected with the proposed scheme is presented.

Signal processing techniques for improving angular resolution performance in homodyne FMCW radar

Homodyne Frequency Modulated Continuous Wave (FMCW) radar results LO (Local Oscillator) signal leakage from structural properties of a transceiver. The phenomenon of LO signal leakage degrades high resolution performance. Therefore many researchers have been trying to overcome and improve the technical shortcoming of homodyne transceiver. This paper proposes new signal processing techniques and implementations to improve high angular resolution estimation for homodyne FMCW radar. It examines several multiple signal classification (MUSIC) algorithms such as conventional, Forward/Backward spatial smoothing, and beamspace algorithms and presents typical high resolution signal processing method before describing the proposed signal processing techniques and the results of simulation and real experiment. The high resolution performance of the proposed method is compared to that of general high resolution signal processing based on conventional MUSIC, Forward/Backward spatial smoothing (FBSS) MUSIC, and beamspace (BS) MUSIC algorithms in terms of directions of arrival (DOA).

Ranging Performance for Spoofer Localization using Receiver Clock Offset

In this paper, the performance of ranging measurement, which is generated using two receiver clock offsets in one receiver, was analyzed. A spoofer transmits a counterfeited spoofing signal which is similar to the GPS signal with hostile purposes, so the same tracking technique can be applied to the spoofing signal. The multi-correlator can generate two receiver clock offsets in one receiver. The difference between these two clock offsets consists of the path length from the spoofer to the receiver and the delay of spoofer system. Thus, in this paper, the ranging measurement was evaluated by the spoofer localization performance based on the time-of-arrival (TOA) technique. The results of simulation and real-world experiments show that the position and the system clock offset of the spoofer could be estimated successfully.

Unambiguous Tracking Technique Based on Sub-Carrier Pulse Grouping for TMBOC-Modulated Signals in GPS

Based on grouping the pulses that compose the sub-carrier of the time-multiplexed binary offset carrier (TMBOC), we present an unambiguous correlation function that has no side-peaks causing the ambiguity in the TMBOC signal tracking, and also, that has a higher degree of the sharpness of the main-peak (DSM) over those of the conventional unambiguous correlation functions. Splitting the pulses composing the TMBOC sub-carrier into 12 groups, and, subsequently, forming the 12 group correlations corresponding to the 12 groups, we investigate the contribution of each of the 12 group correlations to the side peaks and main peak of the TMBOC autocorrelation function. Then, we propose a combining method of the 12 group correlations based on the investigation to remove the side peaks while improving the DSM. Numerical results demonstrate that the proposed unambiguous correlation function not only has no side-peaks, but also has a higher DSM, and, consequently, has a better tracking error performance than those of the conventional unambiguous correlation functions.

Performance analysis of beamspace MUSIC with beamforming angle

The relation between beamforming and related beamspace high resolution direction-of-arrival (DOA) estimation is studied in this paper. Good DOA estimates are obtainable by applying MUSIC to the beam outputs directly. DOA estimation performance is related to the beamforming angle and inter-beam angle. This paper uses the forward-backward spatial smoothing technique as the preprocessor of beamspace MUSIC. We show by computer simulation that DOA estimates vary with inter-beam angle. We also show that DOA estimates of beamspace MUSIC are changed with beamforming angle.

A Successive Repeat-back Jamming Cancellation Scheme Using a Combined-PRN Signal to Mitigate Repeat-back Jamming for GNSS Receivers

In this paper, an effective repeat-back jamming (RBJ) mitigation scheme known assuccessive repeat-back jamming cancellation (SRC) is proposed for the utilization of the successive interference cancellation (SIC) algorithm which is used to mitigate the near-far effect and the multiple-access interference for code division multiple-access communication systems. The proposed scheme uses a combined pseudo-random noise (C-PRN) signal from the estimated major parameters of RBJ signals. To evaluate the performance of the proposed scheme, the root mean squared (RMS) code tracking errors are shown according to the standard deviation of the parameter estimation errors of an RBJ signal, and using the well-known major parameters estimation schemes with a C-PRN signal through Monte-Carlo simulation.

A Novel Carrier-to-noise Power Ratio Estimation Scheme with Low Complexity for GNSS Receivers

Abstract: The carrier-to-noise power ratio is a key parameter for determining the reliability of PVT (Position, Velocity, and Time) solutions which are obtained by a GNSS (Global Navigation Satellite System) receiver. It is also used for locking a tracking loop, deciding the re-acquisition process, and processing advanced navigation in the receiver subsystem. The representative carrier-to-noise power ratio estimation schemes are the narrowband-wideband power ratio method (NW), the MM (Moment Method), and Beaulieu’s method (BL). The NW scheme is the most classical one for commercial GNSS receivers. It is often used as an authoritative benchmark for assessing carrier-to-noise power estimation schemes. The MM scheme is the least biased solution among them, and the BL scheme is a simpler scheme than the MM scheme. This paper focuses on the less biased estimation with low complexity when the residual phase noise remains, then proposes a novel carrier-to-noise power ratio estimation scheme with low complexity for GNSS receivers. The asymptotic bias of the proposed scheme is derived and compared with others, and the simulation results demonstrate that the complexity of the proposed scheme is lowest among them, while the estimation performance of the proposed scheme is similar to those of the BL and MM schemes in normal and high gained reception environments.Keywords: GNSS, carrier-to-noise power ratio estimator, complexity, residual phase error, asymptotic bias

Cramer-Rao Lower Bound of Effective Carrier-to-noise Power Ratio Estimation for a GPS L1 C/A Signal under Band-limited White Noise Jamming Environments

Abstract: In this paper, we derive the CRLB (Cramer-Rao Lower Bound) of effective carrier-to-noise power ratio (  ) estimation for a GPS (Global Positioning System) L1 C/A (Coarse/Acquisition) signal under band-limited white noise jamming environments. The quality of a received GPS signal is commonly described in terms of its   , implying that the noise is white and thus can be described by scalar noise density. However, if some intentional interference is received to a victim GPS receiver, then the   is no longer the efficacious performance indicator. The correct and straightforward measurement to analyze the receiving situation is the effective   . In this paper, we consider a band-limited white noise jamming whose bandwidth is 2MHz and is the same as one of the first null-to-null bandwidth of the GPS L1 C/A signal. Keywords: GNSS, GPS, band-limited white noise jamming, carrier-to-noise power ratio, Cramer-Rao lower bound, effective carrier-to-noise power ratio Copyright© ICROS 2014