Multilayer subband-based video coding

A motion compensated interframe subband coding algorithm suitable for a wide range of video coding applications is described. In this approach the spectrum of each frame of video signal is first decomposed into smaller frequency bands where each can then be coded accordingly. For the best performance a combination of hybrid DCT/DPCM (discrete cosine transform/differential pulse code modulation), interframe DPCM, and intraframe PCM was considered. To preserve its hierarchical structure each band is coded independently of higher frequency bands but can share information with the lower bands. A simulation was carried out for HDTV sequences     

A Link-Level Simulator of the cdma2000 Reverse-Link Physical Layer

The cdma2000 system is an evolutionary enhancement of the IS-95 standards which support 3G services defined by the International Telecommunications Union (ITU). cdma2000 comes in two phases: 1XRTT and 3XRTT (1X and 3X indicates the number of 1.25 MHz wide radio carrier channels used and RTT stands for Radio Transmission Technology). The cdma2000 1XRTT, which operates within a 1.25 MHz bandwidth, can be utilized in existing IS-95 CDMA channels as it uses the same bandwidth, while 3XRTT requires the commitment of 5 MHz bandwidth to support higher data rates. This paper describes a software model implementation of the cdma2000 reverse link and its application for evaluating the effect of rake receiver design parameters on the system performance under various multipath fading conditions. The cdma2000 models were developed at the National Institute of Standards and Technology (NIST), using SPW (Signal Processing Worksystem) commercial software tools. The model has been developed in a generic manner that includes all the reverse link six radio configurations and their corresponding data rates, according to cdma2000 specifications. After briefly reviewing the traffic channel characteristics of the cdma2000 reverse link (subscriber to base station), the paper discusses the rake receiver implementation including an ideal rake receiver. It then evaluates the performance of each receiver for a Spreading Rate 3 (3XRTT) operation, which is considered as a true “3G” cdma2000 technology. These evaluations are based on the vehicular IMT-2000 (International Mobile Telecommunication 2000) channel model using the link budget defined in cdma2000 specifications for the reverse link.     

Conditional Run-Length and Variable-Length Coding of Digital Pictures

In earlier publications, we have presented two coding schemes which take into account the conditional statistics of input signals. In the first scheme, the codewords are assigned in such a way as to provide a signal with long runs of zeros and ones. In the second scheme, each picture element is coded by variable-length codewords according to the values of previously transmitted PEL's. In this paper, by providing further results, we examine these coding schemes in greater detail. The performance of both schemes in terms of entropy and bit rate are compared with an optimum predictive coder. The simulation results indicate that these schemes have a significant advantage over standard predictive encoders. Methods to reduce the storage requirement for the encoder and decoder codebooks are also discussed.     

Single diode laser sensor for wide-range H2O temperature measurements

A single diode laser absorption sensor (near 1477 nm) useful for simultaneous temperature and H2O concentration measurements is developed. The diode laser tunes approximately 1.2 cm(-1) over three H2O absorption transitions in each measurement. The line strengths of the transitions are measured over a temperature range from 468 to 977 K, based on high-resolution absorption measurements in a heated static cell. The results indicate that the selected transitions are suitable for sensitive temperature measurements in atmospheric pressure combustion systems using absorption line ratios. Comparing the results with HITRAN 96 data, it appears that these transitions will be sensitive over a wide range of temperatures (450-2000 K), suggesting applicability for combustion measurements.     

Conditional entropy encoding of log-PCM speech

The conditional dependence between the current and previously quantised samples in 64 kbit/s ?-law PCM speech is exploited to noiselessly reduce the average transmitted bit rate. From the conditional probabilities, the conditional entropy and average Huffman code word lengths were computed. The average data rate reduction for the first-order noiseless encoder was found to be 12 kbit/s.     

3-D Motion Estimation Using Range Data

Advanced vehicle-based safety and warning systems use laser scanners to measure road geometry (position and curvature) and range to obstacles in order to warn a driver of an impending crash and/or to activate safety devices (air bags, brakes, and steering). In order to objectively quantify the performance of such a system, the reference system must be an order of magnitude more accurate than the sensors used by the warning system. This can be achieved by using high-resolution range images that can accurately perform object tracking and velocity estimation. Currently, this is very difficult to achieve when the measurements are taken from fast moving vehicles. Thus, the main objective is to improve motion estimation, which involves both the rotational and translation movements of objects. In this respect, an innovative recursive motion-estimation technique that can take advantage of the in-depth resolution (range) to perform accurate estimation of objects that have undergone three-dimensional (3-D) translational and rotational movements is presented. This approach iteratively aims at minimizing the error between the object in the current frame and its compensated object using estimated-motion displacement from the previous range measurements. In addition, in order to use the range data on the nonrectangular grid in the Cartesian coordinate, two approaches have been considered: 1) membrane fit, which interpolates the nonrectangular grid to the rectangular grid, and 2) the nonrectangular-grid range data by employing derivative filters and the proposed transformation between the Cartesian coordinates and the sensor-centered coordinates. The effectiveness of the proposed scheme is demonstrated for sequences of moving-range images