Position determination using the DTV segment sync signal

The conventional global positioning system (GPS) can often fail to provide position determination for a mobile user in indoor and urban environments. To cope with GPS failure in such environments, a new navigation system which utilizes a terrestrial digital multimedia broadcasting (T-DMB) signal to obtain the mobile user's position is presented. Since the T-DMB transmitters in Korea construct a single frequency network (SFN), which forces the transmitters to be synchronized, the mobile user can measure a time difference of arrival (TDOA) for all audible T-DMB transmitter pairs. The time difference between T-DMB transmitters is converted to a distance difference by multiplying the time difference by the speed of light. Using these measurements and a TDOA positioning method, the mobile user position can be estimated. An experiment with a T-DMB receiver and a data acquisition (DAQ) board is performed in Seoul to analyze the error characteristic of TDOA measurements. It is certified that the measurement error is bounded under 300 m and can be used to determine the mobile user's position with a small standard deviation.

This paper presents a research of current practices in audio description broadcast in Spanish television channels. The results of this research show that in some television channels the audio description is broadcasted in 'receiver mix audio description' mode while in other channels the alternative used is 'broadcaster mix audio description' mode. In both cases, correct signalling and correct audio description coding is crucial so that digital television receivers can recognize audio description in the broadcast signal and reproduce it upon user request. The current practice of audio description broadcast in Spanish television channels only partially fulfils DVB standard. In addition, not all digital television receivers are able to reproduce appropriately the wide range of options defined in DVB to convey audio description in the television channels. The consequence for the users is less availability of audio description services than expected. Some of the problems detected for the activation of audio description in users' receivers can be solved by applying some enhancement to signalling information used by broadcasters in their DVB television channels. Finally, some recommendations for the users are included to present the key aspects for audio description activation in their digital television receivers.

In a single frequency network (SFN) for the Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) system, co-channel interference induced by the multiple transmitters and/or repeaters which use the same output channel is inevitable. Since the presence of interference results in the performance degradation of the SFN, it is crucial to manipulate the interference by adjusting the transmit power and the emission time of each transmitter and repeater within the SFN. In the ATSC terrestrial DTV system, in order to facilitate the interference manipulation process, a transmitter identification (TxID) signal which is embedded in the transmit signal from each transmitter and repeater is recommended. However, such an embedded signal may degrade the DTV signal quality even though the injection level of the TxID signal is very low compared to the DTV signal. Hence, the effect of the TxID signal on the DTV signal needs to be investigated before deploying the SFN with TxID signal. In this paper, the effect of the TxID signal on the performance of legacy DTV receivers is investigated not only with extensive computer simulation but also with laboratory and field tests. According to the various test results, the average performance loss of the conventional DTV receiver due to the TxID signal is less than 0.2 dB when the TxID signal is injected at 30 dB below the DTV signal power.

We propose the methodology of field strength prediction for a digital television (DTV) receiver by virtue of Rec. ITU-R P.1546. The curves shown in this Rec. represent the point-to area field strength for 1kW effective radiated power in the 30 MHz ∼ 3000 MHz. Some computed results are illustrated here from the formulation of field strength for DTV receiver. It was shown that the error of field strength value for dense urban area (R = 30 m) is in the range of about 6.8 ∼ 11.5 % compared with the Okumura-Hata model under some conditions. In addition comparison of service distance between analog and digital TV receivers has been also illustrated. The presented method provides the predicted values of field strength for TV receiver whether transmission quality can be assured or not, and it can be also used to get the protection ratio or separated distance for frequency sharing in the same or adjacent band.

In this paper, we introduce an integration method of Global Positioning System (GPS) pseudorange and time difference of arrival (TDOA) measurements from a pilot signal of a wireless communication network to solve the navigation problem in the case that the number of visible GPS satellites is not sufficient. TDOA measurements are known to have poor accuracy due to technical limitations of a communication system and propagation environments. The major error source of TDOA is the non-line-of-sight (NLOS). To estimate the TDOA error in a cellular network, we propose a method using a Kalman filter for each TDOA channel. In addition, a method to measure TDOA errors is proposed. Some simulations and real tests are conducted to evaluate the performance of the proposed methods. Real experiments are conducted near the city center of Seoul. Using a commercial cellular phone and a GPS receiver, pseudorange of GPS and TDOAs are measured. Test results show that the proposed methods continuously provide subscribers a reasonably accurate location in the case that GPS data are occasionally insufficient.

Broadcasting has always been limited by interference between signals. With the introduction of digital terrestrial television broadcasting (DTTB) in the existing analog TV channels, interference remains a limiting factor in the post-transition era after analog signals are turned off and the spectrum is repacked. The use of first adjacent channels and the "UHF taboo channels" in the same community without transmitter spacing limits is unprecedented, and is a challenge to digital television (DTV) receiver designers. This paper discusses the nature of interference between DTV signals on adjacent and UHF taboo channels, and propose some solutions to receiver designers to mitigate the problem.

A growing number of very simple parallel applications can benefit from the availability of very large computing resource pools that are exploited in an opportunistic way to considerably speed up the processing of these applications. In particular, many applications can scale out to take advantage of the availability of thousands, or even millions, of processors that can be simultaneously used. Some large-scale distributed computing infrastructures (DCI) have already been successfully assembled to this end. However, these DCI are normally designed to cater to specific kinds of applications, and their assemblage is not only costly, but also time consuming. We propose a novel architecture, named OddCI (On-demand DCI), for the cheap, fast and on-demand instantiation and dismantle of very large DCI. These characteristics allow application users to dynamically commission DCI that can cost-effectively be customized to their particular needs, and disposed after being used. Our approach leverages on broadcast communication as an efficient mechanism to enable aggregation of geographically distributed computing resources, including millions of non-traditional processing devices such as mobile phones, and digital television (DTV) receivers. We discuss how the proposed architecture can be implemented on top of a network of DTV receivers, providing evidences of both the technical, as well as the operational feasibility of the OddCI architecture.

MPEG-2 test stream for evaluation the static picture quality of digital television (DTV) should meet both good picture quality and stable bit rate. In this paper, we present a method for generating a high quality test stream to evaluate the static picture quality in DTV receiver. The proposed method is suitable for encoding the static test pattern, such as multiburst and crosshatch, and is based on user-defined quantization and adaptive zero stuffing algorithm. The user-defined quantization is suitable for minimizing the quantization error, which is the reason of degradation of picture quality, and the adaptive zero stuffing algorithm is used to solve the overflow of video buffer verifier (VBV) buffer while encoding process by MPEG-2 encoder. Experimental results show that the average PSNR and the bit rate of the proposed method have more efficient and stable than those of the conventional.

This paper evaluates the performance of a semidistributed multinode time-of-arrival (TOA) anddirection-of-arrival (DOA) fusion localization technique in terms of localization circular error probability (CEP). The localization technique is applicable in mobile ad hoc networks (MANETs) when global positioning system (GPS) is not available (GPS denied environments). The localization CEP of the technique is derived theoretically and verified via simulations. In addition, we theoretically derive the localization CEP of GPS-aided TOA fusion and GPS-aided DOA fusion techniques, which are also applicable in MANETs. Finally, we compare these three localization techniques theoretically and via simulations. The comparison confirms that in moderate scale MANETs, the multinode TOA-DOA fusion localization technique achieves the best performance; while in large scale MANETs, GPS-aided TOA fusion leads to the best performance.

Low-Cost Livestock Global Positioning System Collar from Commercial Off-the-Shelf Parts

Global positioning system (GPS) technologies have improved the ability of researchers to monitor wildlife; however, use of these technologies is often limited by monetary costs. Some researchers have begun to use commercially available GPS loggers as a less expensive means of tracking wildlife, but data regarding performance of these devices are limited. We tested a commercially available GPS logger (i–gotU GT–120) by placing loggers at ground control points with locations known to < 30 cm. In a preliminary investigation, we collected locations every 15 minutes for several days to estimate location error (LE) and circular error probable (CEP). Using similar methods, we then investigated the influence of cover on LE, CEP, and fix success rate (FSR) by constructing cover over ground control points. We found mean LE was < 10 m and mean 50% CEP was < 7 m. FSR was not significantly influenced by cover and in all treatments remained near 100%. Cover had a minor but significant effect on LE. Denser cover was associated with higher mean LE, but the difference in LE between the no cover and highest cover treatments was only 2.2 m. Finally, the most commonly used commercially available devices provide a measure of estimated horizontal position error (EHPE) which potentially may be used to filter inaccurate locations. Using data combined from the preliminary and cover investigations, we modeled LE as a function of EHPE and number of satellites. We found support for use of both EHPE and number of satellites in predicting LE; however, use of EHPE to filter inaccurate locations resulted in the loss of many locations with low error in return for only modest improvements in LE. Even without filtering, the accuracy of the logger was likely sufficient for studies which can accept average location errors of approximately 10 m.

The Affordable Guided Airdrop System (AGAS) is being evaluated as a low-cost alternative for meeting the military’ s requirements for precision airdrop. Designed to bridge the gap between relatively expensive high-glide ratio parafoil systems and uncontrolled ballistic parachutes, the AGAS concept offers the benee ts of high-altitude parachute releases as well as the potential for highly accurate point-of-use delivery of material. The design goal of the AGAS development is to provide a guidance, navigation, and control system that can be placed in line with cargo parachute systems, for example the G-12 e at-circular parachute, and standard delivery containers (A-22) without modifying these e elded systems. The AGAS is required to provide an accuracy of 328 ft (100 m), circular error probable (CEP), with a desired goal of 164 ft (50 m) CEP. The feasibility of this concept was investigated through modeling and simulation. A three-degree-of-freedom (3DOF) point mass e ight dynamics model, sensor models of a commercial global positioning system (GPS) receiver and magnetic compass, and a model of the control and actuator system were incorporated into a Monte Carlo simulation tool. A bang-bang controller was implemented with trajectory tracking algorithms using position and heading information. Flight testing, using a radio-controlled scaled prototype, provided parachutedynamic and control response data to support themodeling efforts.Thestudy demonstrated thatthisconcepthas thepotential to providecontrolofpreviously unguided round parachutes to accuracies of approximately 210 ft (64 m) CEP. The program is now continuing into the next phase to include the development of a full-scale prototype system for payloads up to 2200 lb (1000 kg).

This paper presents the current design status and some preliminary calibration/performance analyses of the prototype of a multi-sensor personal navigator currently under development at The Ohio State University. The main purpose of this research project is to develop a theoretical foundation and algorithms which integrate the Global Positioning System (GPS), Micro-electro-mechanical inertial measurement unit (MEMS IMU), barometer and compass to provide seamless position information to support navigation and tracking of ground military and rescue personnel. The system is designed with an open-ended architecture, which would be able to incorporate additional navigation and imaging sensor data, extending the system's operations to the indoor environments. The current target accuracy of the system is at 3–5 m CEP (circular error probable). In the current prototype implementation, the following sensors are integrated in the tightly coupled Extended Kalman Filter (EKF): GPS carrier phase and pseudorange data, Crossbow MEMS IMU400C, PTB220A barometer, and KVH Azimuth 1000 digital compass. This paper focuses on the design architecture of the integrated system and the preliminary performance analysis, with a special emphasis on the navigation during the loss of GPS signal. A brief description of the individual sensors and their calibration is presented, together with the navigation performance of the system of sensors.

The audio decoder in a consumer digital television (DTV) receiver conforming to the Advanced Television Systems Committee (ATSC) specification needs two types of data in order to work properly. The data stream it receives must contain coded audio as well as audio metadata. Audio metadata is a group of parameters that describes the audio program data being transmitted and controls some aspects of how the audio program is presented in the consumer's receiver. This paper will provide an overview of the audio metadata parameters. It will discuss the purpose of the parameters and how they are chosen. The paper will also discuss the effect that each of these parameters has on domestic receiver operation. The operational implications of authoring the different parameters at different points in the production or distribution chain will be examined. Some different methods for authoring the metadata will also be proposed. These methods will include those necessary during the transition period when proper metadata authoring and monitoring equipment may not exist.

Integration of infrastructure based positioning systems and inertial navigation for ubiquitous context-aware engineering applications